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Finally a "proper" stackshot/viewcamera combo

gerald.d

Well-known member
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.
 
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gerald.d

Well-known member
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.
 

Egor

Member
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. :)
 

docmoore

Subscriber and Workshop Member
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
 

Egor

Member
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.
 

docmoore

Subscriber and Workshop Member
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/vision-sensors/readings/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
 
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Egor

Member
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 ;)
 

docmoore

Subscriber and Workshop Member
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
 
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Egor

Member
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
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!"
 

docmoore

Subscriber and Workshop Member
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
 

gerald.d

Well-known member
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.
 

Egor

Member
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
 

dchew

Well-known member
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
 
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Egor

Member
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?)
 

TimoK

Active member
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.
10deg_10cm_1691.jpg10deg_16cm_1692.jpg10degr.jpg
 

TimoK

Active member
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.
 

dchew

Well-known member
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
 

TimoK

Active member
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....)
 

gerald.d

Well-known member
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?
 

TimoK

Active member
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
 
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