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Thread: Finally a "proper" stackshot/viewcamera combo

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    Finally a "proper" stackshot/viewcamera combo

    https://www.facebook.com/CamboBV/vid...5287531533754/

    A friend of mine just worked with Cambo and developed this I am told

    I tried to build something like it years ago with my Ultima

    In any case, this gives the best of both worlds in my opinion as it combines the precision of the cognysis stackshot with the focus rails rear standard of the Cambo Ultima or Actus!

    Totally bitchin for those of use who do a lot of stack work
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    Re: Finally a "proper" stackshot/viewcamera combo

    It is a pity they did not motorize the rail so as not to change the lens to image plane distance. Much better to shift the entire camera than to change focus, which changes image size. Still, a pretty neat setup.

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    Re: Finally a "proper" stackshot/viewcamera combo

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    Quote Originally Posted by Shashin View Post
    It is a pity they did not motorize the rail so as not to change the lens to image plane distance. Much better to shift the entire camera than to change focus, which changes image size. Still, a pretty neat setup.
    If I understand what you are saying correctly, then, No, I disagree. This is a game changer for those of us who do this all the time.
    It is all a matter of "perspective" and background/foreground elements. you wish to keep

    We have always had the ability to move the entire camera. That is what the Cognisys Stack Shot was designed to do...
    And we have always had the ability to make crude adjustments to AF lens barrels, but not "fine adjustments" (analogy would be using your own thumb to measure a small distance vs using actual calipers)

    What this does is combine the fine adjustments of a stepper motor with the focus rail of a view camera!

    There is a fundamental difference in perspective when focus stacking using the entire camera distance to subject as opposed to using the focus lens barrel.
    Lens barrels do not have the fine-tune controls to move in increments as small and precise as the cognisys stack shot stepper motor.
    But whenever I have to chose between moving the entire camera vs using the lens barrel, I almost always chose the lens barrel method because the image, once re-sized and composited in Helicon or Zerene, maintains proper perspective without artifacts due to perspective shifts (as experienced when using whole camera movements)

    You can view the problem at this good link made by Zerene Stacker: Rail vs Lens Stacks
    Last edited by Egor; 28th August 2017 at 10:23.

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    Re: Finally a "proper" stackshot/viewcamera combo

    Egor, moving the image plane is a better why to focus for stacks. That was always the advantage of view camera with close ups or macro subjects. I agree that the setup is really good.

    My point was moving the entire camera without changing the lens to image plane distance is a better solution as magnification is not changing in the stack. Microscopes make stack this way (except the sample/stage is moved relative to the camera). If they had a geared rail mount that shifted the camera, it would be perfect.

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    Re: Finally a "proper" stackshot/viewcamera combo

    Quote Originally Posted by Shashin View Post
    Egor, moving the image plane is a better why to focus for stacks. That was always the advantage of view camera with close ups or macro subjects. I agree that the setup is really good.

    My point was moving the entire camera without changing the lens to image plane distance is a better solution as magnification is not changing in the stack. Microscopes make stack this way (except the sample/stage is moved relative to the camera). If they had a geared rail mount that shifted the camera, it would be perfect.
    Shashin, I guess I just don't understand you here. Please help me. There are only a few variables and I just don't understand your request here...As I just can't figure out what you mean here (I am sure it is just me but we have wanted this capability in product studios for a very very very long time, we have tried all other means)

    Quote Originally Posted by Shashin View Post
    moving the entire camera without changing the lens to image plane distance is a better solution as magnification is not changing in the stack
    That is exactly what this modification does, it moves the rear standard of the view camera so the front standard (lens) to image distance remains constant

    Quote Originally Posted by Shashin View Post
    Microscopes make stack this way (except the sample/stage is moved relative to the camera)
    Do you mean "move the subject instead of the camera or focus rails? If so, what is the difference between that and moving the camera as a whole?

    Quote Originally Posted by Shashin View Post
    If they had a geared rail mount that shifted the camera, it would be perfect
    We had that by just mounting the view camera on the stack shot rail system, done it many times.

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    Re: Finally a "proper" stackshot/viewcamera combo

    Quote Originally Posted by Egor View Post
    Shashin, I guess I just don't understand you here. Please help me. There are only a few variables and I just don't understand your request here...As I just can't figure out what you mean here (I am sure it is just me but we have wanted this capability in product studios for a very very very long time, we have tried all other means)
    I mean keep the lens to film plane the same and change the lens (camera) to subject plane distance. So instead of focusing by changing the position of the lens or sensor, you move the camera or subject. A microscope uses this method by moving the species stage while the "camera" stays fixed. Since a studio would not have a "specimen" setup where you could move that, the better solution would move the camera. Since the view camera rail is usually oriented at a correct angle, moving the rail on its mounting block while keeping the front and rear standard fixed would be ideal.

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    Re: Finally a "proper" stackshot/viewcamera combo

    Can it be possible to make something similar yourself? With limited knowledge I did this automated focus stacker unit, based on a Kirk rail, a stepper motor and some Arduino programming. Sorry, but text are in Norwegian only. but, the schematics can be understood and pictures as well. Some similar units, with all necessary codes can be found on different sources.

    http://photopia.no/artikler/55-hjemm...-stacking-rail



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    Re: Finally a "proper" stackshot/viewcamera combo

    Quote Originally Posted by tomerik1972 View Post
    Can it be possible to make something similar yourself? With limited knowledge I did this automated focus stacker unit, based on a Kirk rail, a stepper motor and some Arduino programming. Sorry, but text are in Norwegian only. but, the schematics can be understood and pictures as well. Some similar units, with all necessary codes can be found on different sources.

    Hjemmelaget "Focus Stacking Rail" - Photopia



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    Nice work, tomerik1972!
    Yes, of course you can make one yourself! What you have there is a DIY stepper motor/shooting rail similar to the Cognisys StackShot.
    The StackShot is about $500 USD ready to go out of the box with controller

    The difference is that this stepper motor is connected directly to the focusing rear standard rail of a MFD view camera (Cambo Ultima 23D) and allows focus stacking captures using the "Lens Barrel Ring Method" with front standard movements.
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    Re: Finally a "proper" stackshot/viewcamera combo

    As Egor already wrote, there's no need for another device that enables moving the complete camera. The Cognisys stacking rail can do that for you.

    The idea behind the way we use the Cognisys motor is, that the front standard is used to get the plane of focus where you need it. After that, it can stay where it is. The actual stacking is done by moving the rear standard in small increments. So a combination of stacking and some Scheimpflug.
    Cambo Photographic Industry BV - www.cambo.com
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    Re: Finally a "proper" stackshot/viewcamera combo

    Can the Cambo Actus Mini be configured to work with the Cognisys stepper motor and rear standard focusing, or just the Actus XL 35,DB?

    TIA
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    Re: Finally a "proper" stackshot/viewcamera combo

    The set-up shown on the Actus-XL/Ultima is not suitable for use on an Actus mini. The Stackshot motor moves back and forth with the rear standard. That can't be done on an Actus.
    Cambo Photographic Industry BV - www.cambo.com
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    Re: Finally a "proper" stackshot/viewcamera combo

    Quote Originally Posted by Cambo View Post
    The set-up shown on the Actus-XL/Ultima is not suitable for use on an Actus mini. The Stackshot motor moves back and forth with the rear standard. That can't be done on an Actus.
    I actually adapted the Stackshot system to my Actus about a year ago, and have been using it with great success on a regular basis. It is accurate to less than 1/1000th of an inch, and overall the adaptation cost me less than $60. I bought a precision linear rail, and mounted a high resolution Nema 17 stepper motor to it, which is connected to the Stackshot 3X control board. The motor is attached to the focus knob with an anti-backlash coupling to allow a little flex. This allows the motor to move with the rear standard, and I can now make precision stacks with the best large format/enlarger lenses that I own, without any errors that I used to get when the entire camera was on the Stackshot rail. I can also easily disconnect the setup if I don't need it. Here's a quick phone picture to show what it looks like.

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    Re: Finally a "proper" stackshot/viewcamera combo

    [QUOTE actually adapted the Stackshot system to my Actus about a year ago, and have been using it with great success on a regular basis. It is accurate to less than 1/1000th of an inch, and overall the adaptation cost me less than $60. I bought a precision linear rail, and mounted a high resolution Nema 17 stepper motor to it, which is connected to the Stackshot 3X control board. The motor is attached to the focus knob with an anti-backlash coupling to allow a little flex. This allows the motor to move with the rear standard[/QUOTE]

    Shouldn't have said that it can't be done... Everything can be done. Nice piece of work! The size and weight advantage the Actus has over its larger siblings is gone, but obviously this works for you.
    Cambo Photographic Industry BV - www.cambo.com

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    Re: Finally a "proper" stackshot/viewcamera combo

    Indeed. This was actually a quick and dirty setup just to see if it would work. However it could be made much smaller, with a smaller stepper motor and smaller parts. But even the way it is now, it's actually not that bulky.
    PS, Thanks to Matt from Cognisys for all his help with wiring the motor properly. Really nice and helpful people!!
    -------------------
    Zachary Goulko
    www.goulko.com

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    Re: Finally a "proper" stackshot/viewcamera combo

    I'm a little confused here - most probably because I have never had a camera with rear standard movements, and so don't fully understand the concept, but...

    I was always under the impression that once you've applied some lens movements (tilt and swing) to achieve a particular focal plane at a specific distance from the lens axis, that focal plane is only maintained *at that distance*. As soon as you change the focal distance, you need to change the tilt and swing angles on the lens to maintain the same lens axis:focal plane angle.

    Does moving the rear standard whilst keeping the lens fixed get around this problem?

    Kind regards,


    Gerald.

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    Re: Finally a "proper" stackshot/viewcamera combo

    Quote Originally Posted by gerald.d View Post
    I'm a little confused here - most probably because I have never had a camera with rear standard movements, and so don't fully understand the concept, but...

    I was always under the impression that once you've applied some lens movements (tilt and swing) to achieve a particular focal plane at a specific distance from the lens axis, that focal plane is only maintained *at that distance*. As soon as you change the focal distance, you need to change the tilt and swing angles on the lens to maintain the same lens axis:focal plane angle.

    Does moving the rear standard whilst keeping the lens fixed get around this problem?

    Kind regards,


    Gerald.
    That would indeed be the case when moving the complete camera to do the stacking. Here we only move the rear standard. The idea actually comes from a jewelry photographer. Even with a view camera stacking is inevitable when shooting jewelry and he managed to speed up his workflow whilst obtaining perfect results by doing it this way.
    Cambo Photographic Industry BV - www.cambo.com

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    Re: Finally a "proper" stackshot/viewcamera combo

    Quote Originally Posted by gerald.d View Post
    I'm a little confused here - most probably because I have never had a camera with rear standard movements, and so don't fully understand the concept, but...

    I was always under the impression that once you've applied some lens movements (tilt and swing) to achieve a particular focal plane at a specific distance from the lens axis, that focal plane is only maintained *at that distance*. As soon as you change the focal distance, you need to change the tilt and swing angles on the lens to maintain the same lens axis:focal plane angle.

    Does moving the rear standard whilst keeping the lens fixed get around this problem?

    Kind regards,


    Gerald.
    That's correct when moving the complete camera. Reason why we only move the rear standard. The idea came from a jewelry photographer. He managed to speed up his workflow whilst obtaining excellent quality images by doing it this way.
    Cambo Photographic Industry BV - www.cambo.com
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    Re: Finally a "proper" stackshot/viewcamera combo

    Quote Originally Posted by Cambo View Post
    That's correct when moving the complete camera. Reason why we only move the rear standard. The idea came from a jewelry photographer. He managed to speed up his workflow whilst obtaining excellent quality images by doing it this way.
    I'm not talking about moving the entire camera, just the lens.

    If you keep the rear standard fixed and move the front standard, thus changing the focal distance, you need to adjust the tilt and swing (at the lens axis) in order to keep the focal plane at the same angle for every image in the stack.

    If I understand your solution correctly, you set the desired tilt/swing on the lens, lock it down, and then the rear standard is moved to create the stack.

    So to clarify - when moving the rear standard to focus, the tilt and swing angles on the lens do not need to be changed in order to keep the focal plane at the same angle whilst focusing through the stack. Is that correct?

    Kind regards,


    Gerald.

    /edit...

    Ok. So answering my own question...

    View Camera Focus

    The animation there is demonstrating the exact set-up of this solution, yes?

    If I understand correctly, the animation is showing that the angle of the plane of focus DOES change as you move the rear standard.

    I'm a little confused as to why anyone would want to perform a stack where the angle of the focal plane is changing through the stack.

    Would welcome some clarification on the workflow intention here.
    Last edited by gerald.d; 6th September 2017 at 20:47.

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    Re: Finally a "proper" stackshot/viewcamera combo

    Just to expand on my edit to the above post with an example.

    This image is in the 1:1.1 to 1:1.2 magnification range on FF MFDB.



    120mm lens, with depth of field significantly less than 1mm. To get the entire depth of the movement in focus, clearly you need to stack.

    When shooting watches I always prefer to align the focal plane with the watch surface (either dial or, in this instance, case back). This gives a more pleasing focus fall-off, and has the added benefit of minimizing the number of images required for the stack, since you are stacking through the smallest dimension of the subject being shot - its depth.

    However, as indicated above, to achieve this you need to adjust lens tilt/swing angles as you focus through the subject - whether you are focusing by moving the front or rear standards.

    Kind regards,


    Gerald.
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    Re: Finally a "proper" stackshot/viewcamera combo

    [QUOTEIf I understand correctly, the animation is showing that the angle of the plane of focus DOES change as you move the rear standard.


    Gerald.[/QUOTE]

    Not correct. Maybe the animation is not clear enough here, but the front standard is only used to set the plane of focus before you start stacking. It doesn't change during stacking.
    Cambo Photographic Industry BV - www.cambo.com

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    Re: Finally a "proper" stackshot/viewcamera combo

    Quote Originally Posted by Cambo View Post
    If I understand correctly, the animation is showing that the angle of the plane of focus DOES change as you move the rear standard.


    Gerald.
    Not correct. Maybe the animation is not clear enough here, but the front standard is only used to set the plane of focus before you start stacking. It doesn't change during stacking.
    I must be missing something here, or perhaps something is being lost in translation.

    The animation very clearly indicates that with the front standard fixed, when you move the rear standard the angle of the plane of focus with respect to the subject changes.



    Allow me to ask the question once again.

    If you apply tilt and swing to the front standard, and then lock that down, as you move the rear standard in order to create a focus stack, does the initial angle of the plane of focus change, or not?

    Everything I have been able to read on this subject says that yes - it does.

    The workflow for your product would appear to be the following -

    1. Set desired tilt and swing on the lens axis to get the plane of focus where you want.

    2. Lock the front standard.

    3. Move the rear standard in order to create a focus stack.

    My understanding is that when you move the rear standard, the angle of the focal plane with respect to the subject will change. I.e. In the example I provided above, with your solution, I would start with the focal plane aligned with the top of the movement of the watch, but when I get to the end of the stack, the focal plane will no longer be aligned with the bottom of the movement.

    Am I correct or not here?

    Kind regards,

    Gerald.
    Last edited by gerald.d; 7th September 2017 at 20:25.

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    Re: Finally a "proper" stackshot/viewcamera combo

    Anyone?

    I'm totally perplexed here. And it's gone very quiet.

    Remember - what is going on (if the gif I posted is correct), is that as you move the rear standard, the focal plane pivots around the hinge line, not the subject being shot. It would seem within the realms of possibility that by the time you've finished your attempted stack by moving the rear standard that the focal plane isn't even intersecting your subject at all.

    Is it the case that when doing macro stacks the tolerance of the change in the focal plane is such that one doesn't have to worry about any impact on the stack?

    Although to be honest I find that very doubtful because I can see my CAPcam adjusting the lens tilt and swing when it does a stack. Unfortunately the software controlling it doesn't report the actual lens swing and tilt - it's all driven off the desired focal plane angles - so I'm unable to clarify the tolerances required.

    Someone help me out here please.

    Kind regards,

    Gerald.

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    Re: Finally a "proper" stackshot/viewcamera combo

    Quote Originally Posted by gerald.d View Post
    Anyone?

    I'm totally perplexed here. And it's gone very quiet.

    Remember - what is going on (if the gif I posted is correct), is that as you move the rear standard, the focal plane pivots around the hinge line, not the subject being shot. It would seem within the realms of possibility that by the time you've finished your attempted stack by moving the rear standard that the focal plane isn't even intersecting your subject at all.

    Is it the case that when doing macro stacks the tolerance of the change in the focal plane is such that one doesn't have to worry about any impact on the stack?

    Although to be honest I find that very doubtful because I can see my CAPcam adjusting the lens tilt and swing when it does a stack. Unfortunately the software controlling it doesn't report the actual lens swing and tilt - it's all driven off the desired focal plane angles - so I'm unable to clarify the tolerances required.

    Someone help me out here please.

    Kind regards,

    Gerald.
    Let me try and explain this way (because I am swamped at the moment and just don't have time to go thru this entire thread

    What is it that you think happens when you rotate most "internal focusing" spherical lens rings?
    This is the exact same thing except far simpler. The spherical lens rear element is moved back and forth just like the view camera sensor/film plane. The front element is fixed, the focus plane is fixed, the subject is fixed....there is 0 perspective distortion. It is the best of both worlds. Try moving a spherical lens ring in 1/1000-inch increments for instance.

    I hope that helps. I just don't know a better way to explain it other than "it just works". You just have to try it to see the difference. It is what we need, may not be for everybody, but if you are a product shooter, like me, you would want this...big time.

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    Re: Finally a "proper" stackshot/viewcamera combo

    Gerald

    You are correct ... according to the Scheimpflug principle ... moving the rear standard with respect to the lens standard does change the plane of focus ... but the animation is a
    bit exaggerated with respect to the effect of the hinge point.

    Here is a fairly decent description of the change ....

    https://en.wikipedia.org/wiki/Scheimpflug_principle

    Look at the section called Changing The Plane of Focus and in particular Figure 3.

    However ... most elements of the image plane may not be distorted unless the rear standard angle with respect to the lens standard is changed.

    And I assume for macro the length of the subject plane is short enough to keep it within the displaced plane of focus.

    Just a hunch ... but yes the plane of focus does change.

    Regards,

    Bob

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    Re: Finally a "proper" stackshot/viewcamera combo

    Quote Originally Posted by docmoore View Post
    Gerald

    You are correct ... according to the Scheimpflug principle ... moving the rear standard with respect to the lens standard does change the plane of focus ...
    Regards,

    Bob
    Bob, how does the plane of focus change if neither the front element or rear elements tilt in any way? Once the plane of focus is set, moving the front or rear standards simply forward or backward can not change this. If you have a regular camera lens with both front and rear set to 90-deg perpendicular to subject, and you simply move the camera, rear lens element, or front lens elements forward or backward...the PoF does not change. It is set. In order to change the PoF, something has to tilt, either the camera, the lens, or the subject must physically "tilt"... there is no other way.

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    Re: Finally a "proper" stackshot/viewcamera combo

    I did not invent the math and come up with the Scheimpflug principle ... is what it is ... sorry if it does not fit with your view of reality.

    I imagine that the change in the focal plane is not extremely exaggerated for the limits the camera uses ... does not change the physics nor the
    math. Just because you cannot see it does not mean it does not exist.

    If it works it works ... not an attack on your reality ...

    Perhaps this PDF will help


    https://www.cs.cmu.edu/~ILIM/courses...ings/FVC16.pdf

    I spent thirty minutes miming your view ... then did a bit of a search and conformed my response to the aforementioned article.

    Bob
    Last edited by docmoore; 8th September 2017 at 15:13.
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    Re: Finally a "proper" stackshot/viewcamera combo

    Quote Originally Posted by docmoore View Post
    I did invent the math and come up with the Scheimpflug principle ... is what it is ... sorry if it does not fit with your view of reality.

    I imagine that the change in the focal plane is not extremely exaggerated for the limits the camera uses ... does not change the physics nor the
    math. Just because you cannot see it does not mean it does not exist.

    If it works it works ... not an attack on your reality ...

    I spent thirty minutes miming your view ... then did a bit of a search and conformed my response to the aforementioned article.

    Bob
    No worries, Bob...Just can't picture it in any way either theoretically or in actual practice. I am not offended nor do I suffer from cognitive dissonance by this. Haven't you ever heard the phrase "Don't tell someone something is "impossible" while they are in the act of doing it" I use these principals every day all day for over 30 years now. But I could have a wrong assumption, I admit, happens all the time. I will continue to have and use my obviously flawed view to produce work. I guess Cambo, and Cognisys, and Ori, and I are just wrong about this and it doesn't actually work.... but I have thousands of images shot this way that show the PoF does not change with rear standard lateral movements... it looks and functions like we are correct. But I do know what is being discussed as the hinge rule, I just haven't actually experienced it in actual work with view cameras, ever...Doesnt make the theory wrong, just haven't experienced it and have shot a lot with view camera movements over a very long period of time. Perhaps it is like you say, mathematically it is a fact, but practically not significant...Peace
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    Re: Finally a "proper" stackshot/viewcamera combo

    I agree ... a theoretical concern that does not appear in real world situations that the camera is used within ... best of all worlds.

    But to say the math/physics is wrong diminishes your position.

    I would love to use the system with my X1D ... but my inherent impatience may preclude anything so involved.

    Love to see the results ... fascinated with great DOF macros.

    A quote from Mecklinger ....

    "in essence, the hinge rule tells us that if we move the back of the camera (to and fro), closer to or farther from the lens, the plane of sharp focus must pivot on a line a distance J from the lens. In our example this pivot line is on
    the plane of sharp focus directly below the lens. I call that line the hinge line. I call it that because that line is like the pin in a hinge. The plane of sharp focus hinges on that line. As we move the back away from the lens, the plane of sharp focus
    will swing up in front of the camera. If we move the camera back closer to the lens, the plane of sharp focus will swing down, away from the lens.
    (It’s the Scheimpflug rule working consort with the hinge rule that causes this rotation, by the way.)"


    Bob
    Last edited by docmoore; 8th September 2017 at 15:34.
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    Re: Finally a "proper" stackshot/viewcamera combo

    Quote Originally Posted by docmoore View Post
    I agree ... a theoretical concern that does not appear in real world situations that the camera is used within ... best of all worlds.

    But to say the math/physics is wrong diminishes your position.

    I would love to use the system with my X1D ... but my inherent impatience may preclude anything so involved.

    Love to see the results ... fascinated with great DOF macros.

    A quote from Mecklinger ....

    "in essence, the hinge rule tells us that if we move the back of the camera (to and fro), closer to or farther from the lens, the plane of sharp focus must pivot on a line a distance J from the lens. In our example this pivot line is on
    the plane of sharp focus directly below the lens. I call that line the hinge line. I call it that because that line is like the pin in a hinge. The plane of sharp focus hinges on that line. As we move the back away from the lens, the plane of sharp focus
    will swing up in front of the camera. If we move the camera back closer to the lens, the plane of sharp focus will swing down, away from the lens.
    (Its the Scheimpflug rule working consort with the hinge rule that causes this rotation, by the way.)"


    Bob
    I do not question the math or the physics. I am formally trained as an engineer.

    Math vs Practice Joke (one of my favorites from engineering school:

    A mathematician and an engineer agreed to take part in an experiment. They were both placed in a room and at the other end was a beautiful naked woman on a bed. The experimenter said every 30 seconds they would be allowed to travel half the distance between themselves and the woman. The mathematician said "this is pointless" and stormed off. The engineer agreed to go ahead with the experiment anyway. The mathematician exclaimed on his way out "don't you see, you'll never actually reach her?".

    To which the engineer replied, "so what? Pretty soon I'll be close enough for all practical purposes!"
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    Re: Finally a "proper" stackshot/viewcamera combo

    Love it ... the grasshopper never arrives but the engineer does not need to ...

    My experience in 40 years of medical practice ... not all the science is applicable and
    not all the experience prepares you for the unexpected. But if it works ... it works.

    Bob
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    Re: Finally a "proper" stackshot/viewcamera combo

    Quote Originally Posted by docmoore View Post
    Love it ... the grasshopper never arrives but the engineer does not need to ...

    My experience in 40 years of medical practice ... not all the science is applicable and
    not all the experience prepares you for the unexpected. But if it works ... it works.

    Bob
    Thanks for the contributions everyone.

    When I get home on Sunday I'll have a crack at the maths. What I do know is that at the magnification levels that I work at, the change in required lens tilt and swing is significant enough for the CAPcam to appear to make adjustments for as it shoots the stack. It is possible that I am misinterpreting the movements I see on the front standard, but I don't believe that to be the case. At the end of the day, this is a camera with movements of accuracy in the order of microns, which of course could be overkill for many requirements.

    A typical stack, by the way, would be of the order 15 images with 600 micron depth of field, with the focal plane tilted and swung by 20 degrees or so. What I don't know is how that compares to the kind of magnification and tilt/swing angles Egor is working with.

    Kind regards,

    Gerald.

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    Re: Finally a "proper" stackshot/viewcamera combo

    Quote Originally Posted by gerald.d View Post
    Thanks for the contributions everyone.

    A typical stack, by the way, would be of the order 15 images with 600 micron depth of field, with the focal plane tilted and swung by 20 degrees or so. What I don't know is how that compares to the kind of magnification and tilt/swing angles Egor is working with.

    Kind regards,

    Gerald.
    Gerald, honestly I think 90% of what I stack is much larger with much greater tolerances than what you describe there. I do shoot about 2-3 medical devices a month and some jewelry that exceed those tolerances (diamond pendants, capillary plugs, artificial tear ducts, heart valves and the like) but by and large, most products I shoot are bread box size, 10-15 stacks to a set. I won't include architectural because it obviously is way larger tolerances. The beauty of the system I posted about is that it will save us time and allow us to shoot multiple stacks on a production basis with front movements. So if I have 150 watches to shoot, or 1700 shoes all at the same angle and placement, I can use the view camera for such work and turn the production over to an assistant knowing that the stacks will be standardized and perfect every time without much operator error.
    Also, we do have the regular need for serious tolerance work with macro and even small product, but usually on a production scale of 100 or more similar products to be shot.

    I started this thread because I figured some might be interested in this achievement. I think its gone down a road of tech-eze questions that does not interest me; but is obviously interesting to others. Thats how threads go sometimes. I was more hoping that folks would be excited in the breakthrough, especially in the MFD area here as that is one of the main reasons to have a MFD back.

    In any case, if you have a system (cap cam??) that works for you better, and takes into account the hinge rule problem that is apparently a factor in your work, good! I just don't see focus plane changes without a tilt. I never have. I have been doing this a long... long time. Scheimflug and i are good friends, we're like this, we go way back! If you do and it affects your workflow, then maybe this isn't the answer for you. But I assure you, it is for me and many more product shooters out there. Thats all, Peace, Eric

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    Re: Finally a "proper" stackshot/viewcamera combo

    Quote Originally Posted by Egor View Post
    I just don't see focus plane changes without a tilt. I never have. I have been doing this a long... long time. Scheimflug and i are good friends, we're like this, we go way back! If you do and it affects your workflow, then maybe this isn't the answer for you. But I assure you, it is for me and many more product shooters out there. Thats all, Peace, Eric
    Eric,
    I'm with Gerald on this one. In fact, when I explain the Scheimpflug principle to someone I start with this: Rack the focus out to infinity and start dialing in tilt. In this case, the plane of focus is 90 degrees from the film plane, and remains so as you dial in more tilt. In the simple camera-oriented-level landscape image focused at infinity with some lens tilt, the plane of focus is exactly horizontal - 90 degrees from the film plane. The amount of tilt defines how close or far that plane of focus is below the camera. More tilt does not "tilt" the plane of focus; it instead pulls the plane of focus (and the hinge line) up through the ground closer to the camera. The only way to get that plane of focus to tilt up at an angle less than 90 degrees from the film plane is to focus in from infinity by moving either the lens or the film plane further away from each other.

    I admit it is a weird way to look at how this works, but it really helps people understand what is going on, and what movements drive the plane of focus position. I also admit that I have no idea how much focus plane tilt goes on when focus stacking; it may be very minimal and even unnoticeable. But on a grand scale, racking focus in and out is in fact the only way to tilt the plane of focus (i.e. change the angle of incidence of the plane of focus relative to the film plane).

    Dave
    Last edited by dchew; 9th September 2017 at 03:56.
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    Re: Finally a "proper" stackshot/viewcamera combo

    Quote Originally Posted by dchew View Post
    Eric,
    on a grand scale, racking focus in and out is in fact the only way to tilt the plane of focus (i.e. change the angle of incidence of the plane of focus relative to the film plane).

    Dave
    ummm...ok
    I think I will continue to change my plane of focus the way I and everyone I have every known (including Ansel Adams) have been doing it since the late 60's...with the front standard tilts/swings and occasionally with some rear standard tilts/swings...but thats just me (and a few million others...but I'm old and set in my ways, what do I know?)

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    Re: Finally a "proper" stackshot/viewcamera combo

    Quote Originally Posted by gerald.d View Post
    Thanks for the contributions everyone.

    When I get home on Sunday I'll have a crack at the maths. What I do know is that at the magnification levels that I work at, the change in required lens tilt and swing is significant enough for the CAPcam to appear to make adjustments for as it shoots the stack. It is possible that I am misinterpreting the movements I see on the front standard, but I don't believe that to be the case. At the end of the day, this is a camera with movements of accuracy in the order of microns, which of course could be overkill for many requirements.

    A typical stack, by the way, would be of the order 15 images with 600 micron depth of field, with the focal plane tilted and swung by 20 degrees or so. What I don't know is how that compares to the kind of magnification and tilt/swing angles Egor is working with.

    Kind regards,

    Gerald.
    I hope You can solve the maths. I'm not so good in math.
    I made a simple test at close up distance, not even macro.
    What I see is that the angle of focus plane is changing, but not badly, I wonder, I could make a good 6cm thick focus stack of eg. 20 shots.
    The equipment was Cambo Actus mini, Hassy Distagon cf fle 4/50 mm ,used wide open, and as sensor worked Canon 6d.
    I set the maximal tilt, 10 degrees downward and shot two rulers. The distance (from lens front end) to the nearer one was ~35 cm. The second ruler was around 45-46 cm.
    The rulers and the rear standard was vertically levelled. Rear shift up 12 mm (max).
    I took two shots, first one focussed moving the rear standard (with live view) at 10 cm in the near ruler, the second at 16 cm (with rear standard).
    In the resulting pictures I tried find sharp part at the far ruler.
    The distance between rulers was 10,4 cm. (I often make mistakes when measuring things, looking at the picture, I think I focussed the first shot at 9,9 cm)
    Then I draw picture of focal planes. The grey line is parallel with 16 cm line to show focal plane angle change.
    Name:  10deg_10cm_1691.jpg
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    Re: Finally a "proper" stackshot/viewcamera combo

    Quote Originally Posted by dchew View Post
    Eric,
    I'm with Gerald on this one. In fact, when I explain the Scheimpflug principle to someone I start with this: Rack the focus out to infinity and start dialing in tilt. In this case, the plane of focus is 90 degrees from the film plane, and remains so as you dial in more tilt. In the simple camera-oriented-level landscape image focused at infinity with some lens tilt, the plane of focus is exactly horizontal - 90 degrees from the film plane. The amount of tilt defines how close or far that plane of focus is below the camera. More tilt does not "tilt" the plane of focus; it instead pulls the plane of focus (and the hinge line) up through the ground closer to the camera. The only way to get that plane of focus to tilt up at an angle less than 90 degrees from the film plane is to focus in from infinity by moving either the lens or the film plane further away from each other.

    I admit it is a weird way to look at how this works, but it really helps people understand what is going on, and what movements drive the plane of focus position. I also admit that I have no idea how much focus plane tilt goes on when focus stacking; it may be very minimal and even unnoticeable. But on a grand scale, racking focus in and out is in fact the only way to tilt the plane of focus (i.e. change the angle of incidence of the plane of focus relative to the film plane).

    Dave
    It's a different thing shooting at infinity and near to 1:1 magnification.
    You can not set the focal plane to 90 degrees from sensor plane at macro shots except lenses with very short focal length.
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    Re: Finally a "proper" stackshot/viewcamera combo

    Quote Originally Posted by TimoK View Post
    It's a different thing shooting at infinity and near to 1:1 magnification.
    You can not set the focal plane to 90 degrees from sensor plane at macro shots except lenses with very short focal length.
    Yeah. The only way to set the plane of focus 90 degrees from the sensor plane is to focus at infinity with some degree of tilt. Macro is a long way away from infinity!

    Dave
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    Re: Finally a "proper" stackshot/viewcamera combo

    Quote Originally Posted by dchew View Post
    Yeah. The only way to set the plane of focus 90 degrees from the sensor plane is to focus at infinity with some degree of tilt. Macro is a long way away from infinity!

    Dave
    And the macro shots are what gerald.d is interested in. And it's the reason to make focus stacks, seldom landscapes. (but I started to think....)

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    Re: Finally a "proper" stackshot/viewcamera combo

    Quote Originally Posted by Egor View Post
    ummm...ok
    I think I will continue to change my plane of focus the way I and everyone I have every known (including Ansel Adams) have been doing it since the late 60's...with the front standard tilts/swings and occasionally with some rear standard tilts/swings...but thats just me (and a few million others...but I'm old and set in my ways, what do I know?)
    Ansel Adams, not to mention a few million others, regularly produced focus stacks in the 1:1 magnification range using tilt and swing?

    This solution is being lauded and promoted as being ideal for those doing close-up product work. And yet those lauding and promoting it for such work have demonstrated here in this thread a verging on willful lack of understanding as to the facts regarding the impact of camera movements (or lack thereof) when wanting to produce a set of images for focus stacking.

    And that just seems really strange to me.

    Surely it is the responsibility of those promoting this solution to actually understand how it works, and its potential limitations?

    I stress "potential", because it may well be that the use cases this is being promoted for simply won't require changes to the lens tilt and swing during a stack.

    But I will caveat that paragraph with a reminder about what Cambo themselves stated earlier in the thread:

    "The idea behind the way we use the Cognisys motor is, that the front standard is used to get the plane of focus where you need it. After that, it can stay where it is. The actual stacking is done by moving the rear standard in small increments. So a combination of stacking and some Scheimpflug."

    I think following the detailed discussion here it is now accepted that the emphasised sentence is factually wrong. I am surprised that a company coming out with a solution in this area would make such a glaring error.

    (Just for clarity - I understand this stuff, deeply. It's why I invested in a CAPcam two and a half years ago because it was - and, to the best of my knowledge remains - the only camera solution on the planet that can do macro-level tilt, swung, shifted and risen/fallen, front standard movement focus stacks. I tried very politely to give those promoting this solution ample opportunity to recognise their errors by feigning ignorance, but with little to no success.)

    So over to you Cambo. Could you define the limitations where this solution would not be suitable, due to movement of the plane of focus not being countered by adjusting lens tilt and swing during a stack?

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    Re: Finally a "proper" stackshot/viewcamera combo

    Quote Originally Posted by gerald.d View Post
    Ansel Adams, not to mention a few million others, regularly produced focus stacks in the 1:1 magnification range using tilt and swing?

    This solution is being lauded and promoted as being ideal for those doing close-up product work. And yet those lauding and promoting it for such work have demonstrated here in this thread a verging on willful lack of understanding as to the facts regarding the impact of camera movements (or lack thereof) when wanting to produce a set of images for focus stacking.

    And that just seems really strange to me.

    Surely it is the responsibility of those promoting this solution to actually understand how it works, and its potential limitations?

    I stress "potential", because it may well be that the use cases this is being promoted for simply won't require changes to the lens tilt and swing during a stack.

    But I will caveat that paragraph with a reminder about what Cambo themselves stated earlier in the thread:

    "The idea behind the way we use the Cognisys motor is, that the front standard is used to get the plane of focus where you need it. After that, it can stay where it is. The actual stacking is done by moving the rear standard in small increments. So a combination of stacking and some Scheimpflug."

    I think following the detailed discussion here it is now accepted that the emphasised sentence is factually wrong. I am surprised that a company coming out with a solution in this area would make such a glaring error.

    (Just for clarity - I understand this stuff, deeply. It's why I invested in a CAPcam two and a half years ago because it was - and, to the best of my knowledge remains - the only camera solution on the planet that can do macro-level tilt, swung, shifted and risen/fallen, front standard movement focus stacks. I tried very politely to give those promoting this solution ample opportunity to recognise their errors by feigning ignorance, but with little to no success.)

    So over to you Cambo. Could you define the limitations where this solution would not be suitable, due to movement of the plane of focus not being countered by adjusting lens tilt and swing during a stack?
    I send a post about my test with Cambo Actus and rear focussing (w/o motor). For some reason gpi forum blocked my post with some photos.
    My conclusion was that in close-up range I can see focus plane angle changning, but not very much. Not disturbing me. But maybe disturbing the program to make stack
    Last edited by TimoK; 9th September 2017 at 11:24.

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    Re: Finally a "proper" stackshot/viewcamera combo

    The main reason that I added an automated solution for focus stacking to the rear standard of my Actus is because I was getting parallax errors when the entire view camera was on the rail. When I focus stack, it is rare that I combine the stacking with tilts/swings, and if I do it's a small amount in order to reduce the total number of shots required.
    By moving the rear standard the lens remains stationary, and there are no parallax errors on overlapping objects. This also happens when focus stacking with an autofocus lens.
    I stack primarily watches and jewelry, and I've tried all the methods. This by far gives me the best quality stacks, with the least amount of errors/halos.
    Here's a good explanation with a chart:
    https://zerenesystems.com/cms/stacke...ringversusrail
    -------------------
    Zachary Goulko
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    Re: Finally a "proper" stackshot/viewcamera combo

    The main reason that I added an automated solution for focus stacking to the rear standard of my Actus is because I was getting parallax errors when the entire view camera was on the rail. When I focus stack, it is rare that I combine the stacking with tilts/swings, and if I do it's a small amount in order to reduce the total number of shots required.
    By moving the rear standard the lens remains stationary, and there are no parallax errors on overlapping objects. This also happens when focus stacking with an autofocus lens.
    I stack primarily watches and jewelry, and I've tried all the methods. This by far gives me the best quality stacks, with the least amount of errors/halos.
    Here's a good explanation with a chart:
    https://zerenesystems.com/cms/stacke...ringversusrail
    -------------------
    Zachary Goulko
    www.goulko.com

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    Re: Finally a "proper" stackshot/viewcamera combo

    Apologies for the double post, but there seem to be some issues with posting.
    It took 5 attempts to submit the post, but now I see 2 of them.
    -------------------
    Zachary Goulko
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    Re: Finally a "proper" stackshot/viewcamera combo

    I think this is a thread that could be very helpful to a lot of photographers.

    There are a number of fantastic photographers involved in this thread (including numerous CI clients on both sides of the debate) who produce amazing photography and employ focus stacking. I trust them and accept that they know what they are doing and the proof is in their results.

    I am not mathematically advanced - lets say Im challenged - yet I have a somewhat scientific mind, from the standpoint that I like to prove the theory. So when I encounter theory, no matter how accepted it may be, I often still want to see if applied in a real world situation. It comforts my limitations in being able to review a written theory and wrap my head around it completely.

    I read the article from Zeneer Stacker about a year or so ago and thought it made a lot of sense. But in particular I thought the little table they put together of different stacking approaches matrixed with different subject matter was the most interesting part of it, in light of the accepted theory. This theory would not be the first in history that was proven to be correct, only to later determine that under different circumstances, the theory did not hold 100%.

    I would be very interested in seeing some of the participants put the theory to the test and produce some examples that show results from rear standard focus stacking vs whole camera focus stacking (all with tilt), maybe with some variable subject matter. As Ed Harris said in Apollo13 - "Let's work the problem, people!".

    I think everyone would benefit.



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    Re: Finally a "proper" stackshot/viewcamera combo

    Quote Originally Posted by TimoK View Post
    I hope You can solve the maths. I'm not so good in math.
    I made a simple test at close up distance, not even macro.
    What I see is that the angle of focus plane is changing, but not badly, I wonder, I could make a good 6cm thick focus stack of eg. 20 shots.
    The equipment was Cambo Actus mini, Hassy Distagon cf fle 4/50 mm ,used wide open, and as sensor worked Canon 6d.
    I set the maximal tilt, 10 degrees downward and shot two rulers. The distance (from lens front end) to the nearer one was ~35 cm. The second ruler was around 45-46 cm.
    The rulers and the rear standard was vertically levelled. Rear shift up 12 mm (max).
    I took two shots, first one focussed moving the rear standard (with live view) at 10 cm in the near ruler, the second at 16 cm (with rear standard).
    In the resulting pictures I tried find sharp part at the far ruler.
    The distance between rulers was 10,4 cm. (I often make mistakes when measuring things, looking at the picture, I think I focussed the first shot at 9,9 cm)
    Then I draw picture of focal planes. The grey line is parallel with 16 cm line to show focal plane angle change.
    Aha - I think this was the missing post you were referring to previously?

    Thank you for doing this - it's a really brilliant practical demonstration of exactly the point I have been making, which I will return to in a bit. But first some context for the discussion so far.

    I have to be honest here - reading between the lines, I don't actually believe a great number of people have been doing much (if any) focus stacking with tilt at macro-level. I must stress that I am in full agreement with Egor and others that the ability to rack the rear standard for a stack to prevent parallax issues will be of huge benefit to many where little to no lens tilt/swing is applied.

    This solution clearly introduces the possibility of setting front standard tilt/swing and the racking the rear standard, but I don't actually believe that the consequences of being able to do that were fully thought through, either by Cambo or those arguing against the practicalities that I have raised. There is actually no mention of stacking with a tilted focal plane in the first 8 posts of the thread - Egor didn't even bring it up in the initial discussion.

    Cambo then commented in post 9 "The idea behind the way we use the Cognisys motor is, that the front standard is used to get the plane of focus where you need it. After that, it can stay where it is. The actual stacking is done by moving the rear standard in small increments."

    As stated before, I do not believe the person making this comment understood at that point the error they were making. In my view, and in the context of the discussion, I think they actually believed that the angle of the focal plane would not change as the camera was focused through the stack.

    rodenstock then shares his great self-built solution that he's been successfully using for a year or so. Again - this solution provides the ability to tilt the lens and then rack the rear standard for the stack, but crucially, he later in the thread states "The main reason that I added an automated solution for focus stacking to the rear standard of my Actus is because I was getting parallax errors when the entire view camera was on the rail. When I focus stack, it is rare that I combine the stacking with tilts/swings, and if I do it's a small amount in order to reduce the total number of shots required."

    In the interchange between myself and Cambo, it is totally evident that Cambo simply did not understand the problem. Yes, so this solution came about from the requirements of a jewelry photographer, but there is absolutely no suggestion that the photographer concerned actually intended to use this solution with tilt applied - only that "he managed to speed up his workflow whilst obtaining perfect results by doing it this way."

    It would be very helpful if the photographer concerned would comment on what their workflow is.

    Even after multiple challenges, Cambo still insisted that I was "Not correct. Maybe the animation is not clear enough here, but the front standard is only used to set the plane of focus before you start stacking. It doesn't change during stacking."

    Well, you've just demonstrated with a brilliantly conceived practical example that in fact, it is highly relevant - even when we are not remotely close to a macro situation. And the great thing (for me), is that I can just do the maths on your practical demonstration, rather than a theoretical example.

    What your test shows is the problems people are going to run into if they rely on Cambo's advice, set tilt on the front standard in order to get the plane of focus where they want, and then rack the rear standard.

    The maths

    If I may interpret your test this way, you are simulating an attempt to shoot a "box" that is 113mm in length (the hypotenuse of the 104mm base by 45mm high (144mm height on the rear ruler less 99mm height on the front) right angled triangle).

    This box is 61mm deep (160mm less 99mm) - to keep things simple here, I will assume the box has a parallelogram profile. The large flat surface of the box presents an angle of around 23 degrees to the horizontal (the angle to the horizontal where you mark 99mm in your diagram), and the complexities of the Scheimpflug calculations means that a 10 degree tilt will get the whole of the surface of the box in focus when the near edge of the box is 99mm from the camera.

    Now - imagine this "box" is not solid. Imagine it is simply created from thin bits of wood that form the 12 edges of the box.

    You now rack the rear standard to get the nearest edge of the rear surface of the box into focus at 160mm from the camera. The tilt angle remains the same of course.

    But what about the far edge of the rear surface of the box? Well, on the last image of your stack, it will be nowhere near in focus. Because the focal plane now falls fully 17mm beyond the position of the far edge of the rear surface. (17mm being the difference between (160-99) and (222-144)).

    The focal plane angle with respect to the horizontal has changed from 23 degrees to 31 degrees.

    Conclusion

    I'd say that with the help of the test you performed, we can pretty much categorically conclude that in many situations - even those not remotely approaching macro level maginifcation, those who rely on fixing movements on the front standard and then racking the rear standard to perform a focus stack - as recommended by Cambo - are going to run into some pretty significant challenges.

    They will end up with the focal plane angle changing substantially, and they will have to over-shoot the stack in order to ensure they get the entire volume in focus that they require. No prizes given for who works it out, but if anyone wants to have some fun - tell me what the stack parameters would have to be in order to get the cube I discussed to explain the maths behind your example fully in focus.

    Kind regards,


    Gerald.

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    Re: Finally a "proper" stackshot/viewcamera combo

    The information shared has so many things to learn from this which can be helpful to the photographer. Appreciate!

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    Subscriber and Workshop Member MGrayson's Avatar
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    Re: Finally a "proper" stackshot/viewcamera combo

    I don't know if this image is helpful, but it is true. Forgetting the film plane for a second, and assuming an ideal thin lens without field curvature, a lens takes any plane in front of it to another plane behind it. These two planes are in focus with respect to each other. The two planes are either parallel, or intersect on a line that also lies in the lens plane. If you try to imagine families of these planes, you see what happens in stacking experiments. There are purely geometrical ways to determine paired planes of focus (Scheimpflug and hinges) or you can use the fact that, along the lens axis, pairs of points in focus satisfy 1/a + 1/b = 1/f, where a and b are the distances to the lens and f is its focal length.

    Here's an example showing what happens as we rack the film plane forward while keeping a tilted lens fixed. Note the second hinge point, although I did these by the thin lens equation.



    Best,

    Matt
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    Re: Finally a "proper" stackshot/viewcamera combo

    More to the point, if you have an object at some angle to the lens, its in-focus points on the other side of the lens (labeled, confusingly, "Image") will not be arranged in any easy way to capture:



    The film plane's relation to the lens will not ideally be fixed wrt the lens. You would want the film plane to lie along either set of red lines, depending on which way you wanted to stack.

    --Matt
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    Senior Member dchew's Avatar
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    Re: Finally a "proper" stackshot/viewcamera combo

    This post is not about macro, so in that regard it is off-topic. I do think there are a few things to point out that are relevant and might help, as per Steve Hendrix’s request. At least for those of us who don’t have access to Gerald’s CapCam! Also, as I mentioned above, I look at this stuff a bit differently than most so this post may help dispel how crazy I am (I’m still a little crazy, but hopefully not that crazy).

    I noticed over several years that most people think of lens tilt as tilting the plane of focus. In other words, there is a causation we have in our brains between the degree of tilt and the degree to which the plane of focus is “laid down” flat. In my opinion, this perceived connection is one of the major sources of confusion associated with lens tilt and the Scheimpflug principle.

    There is a correlation between lens tilt and plane of focus angle, but not when focused at infinity. In fact, even when focused in from infinity the rear DoF plane angle does not change at all as you dial in more or less tilt, so I find it more useful to think of it this way: As you dial in more tilt, you are simply pulling the DoF wedge up through the ground closer to the camera because the hinge point is moving up.

    First, a model description. To keep this simple, everything described below is with the camera level to the horizon both in pitch and roll:
    Imagine a threaded rod attached to the bottom of the camera that extends down through the ground infinitely far. The threaded rod is fixed and in line with the film plane, but the threads spin as you dial lens tilt in and out.

    As soon as you dial in any small amount of tilt, say 0.01 degrees, something magical happens: the normal parallel planes in the standard DoF (near DoF, plane of focus, far DoF) flip from being parallel planes out in front of the camera to being a wedge, or cone of DoF, with a point of origin (where the lines converge) mounted on that threaded rod. I will refer to that as the “head” of our cone of DoF. As we dial in more tilt, the threads rotate and pull that point of origin (head) up from infinitely far underground toward the base of our camera.

    If the lens is focused at infinity, the plane of focus is 90 degrees from the film plane and, since our camera is oriented with the horizon, the plane of focus is also parallel with the ground that extends out to infinity in front of the camera. It remains 90 degrees from the film plane regardless of how much tilt we dial in. Focused at infinity, the only thing more tilt does is pull that hinge line up through the ground closer to the base of the camera; the plane of focus remains flat, 90 degrees from the film plane.



    Now we add the focusing variable: Adding to the threaded rod model, let’s add a rope that extends from the lens down, and is tied some point out from the head, at the “waist” of the plane of focus. Close to the point of origin where the near DoF, plane of focus and far DoF converge, but just a wee bit out from that point of origin. Like this:



    I know that picture isn’t an accurate description of the angles and the math. But for this explanation it should be good enough…

    Now a little more magic: Whenever the lens is focused at infinity, the rope is just long enough to keep the plane of focus 90 degrees from the film plane. As we pull in focus from infinity, the rope will get shorter and pull the plane of focus up from horizontal.

    To prove all this, I need to give a shameless plug to Torger’s Lumariver DoF app:
    www.lumariver.com. Below are several screenshots from Lumariver.

    First, I show what happens as more tilt is dialed in with the lens focused at infinity. Note how the hinge line gets pulled up through the ground closer to the base of the camera, from 11 ft @ 1 degree to 5.6 ft at 2 degrees:



    Second, showing the “standard” landscape application, where the far DoF is set along the horizon, 90 degrees from the film plane. We do this by dialing in focus from infinity:



    Third, now that the rear DoF plane is horizontal we dial in more tilt.


    A few things to highlight:
    1. More tilt pulls the point of origin up the threaded rod
    2. More tilt scrubs (diminishes) DoF
    3. The far DoF remains horizontal if we don’t change the focus distance dialed on the lens.
    4. The plane of focus does, indeed, “lay down.” But I like to think of this as being due to the DoF being scrubbed or squashed. You, of course, can look at it however you want!


    Fourth, a sequence of maintaining the same tilt (1.5 degrees), but dialing in focus from infinity. Hinge point doesn’t move, but our rope gets reeled in, which pulls up the cone of DoF.



    Fifth, the difference between dialing in more tilt to get something close in focus, vs reeling in the focus point. In many cases, focusing closer helps because the DoF remains the same width. More tilt brings the plane of focus closer to the ground, but at the expense of height. The ground is all sharp, but the top of the tree or mountain might get blurry as you dial in more tilt. The upper right corner of each image depicts the DoF wedge projected at infinity on the film plane. In the third image, it is the highest, 31mm above the center line of the film/sensor (assuming no rise/fall, but that's another story...).



    In summary, I think it is more useful to think of focus as the tool that tilts the plane of focus and cone of DoF. The degree of lens tilt defines how far the head of that cone sits below the camera. It is true that when focused in closer than infinity, changing the degree of tilt does “tip” the plane of focus. But it does not change the angle of the rear DoF line at all.

    Again, thanks to Torger!

    Dave

    GO TRIBE!
    Last edited by dchew; 12th September 2017 at 16:11.
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    Re: Finally a "proper" stackshot/viewcamera combo

    Dave,

    Who are we kidding? People want gizmos that work. Projective geometry is only useful if you want to understand WHY they work.

    ,

    Matt
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