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Finally a "proper" stackshot/viewcamera combo

Egor

Member
https://www.facebook.com/CamboBV/videos/1585287531533754/

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
 

Shashin

Well-known member
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.
 

Egor

Member
Rail-vs-Lens-example.jpg
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
 
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Shashin

Well-known member
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.
 

Egor

Member
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)

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

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?

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.
 

Shashin

Well-known member
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.
 

Egor

Member
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



View attachment 128903View attachment 128904
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.
 

Cambo

Member
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.
 

GlenC

Member
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
 

Cambo

Member
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.
 

zachary_goulko

New member
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.

 

Cambo

Member
[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. :thumbs:
 

zachary_goulko

New member
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!!
 

gerald.d

Well-known member
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.
 

Cambo

Member
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

Member
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.
 

gerald.d

Well-known member
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.
 
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gerald.d

Well-known member
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.
 

Cambo

Member
[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.
 
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