Subject Coupled-to or Isolated-from Camera?

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Doppler9000
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Subject Coupled-to or Isolated-from Camera?

Post by Doppler9000 »

I am working on my studio design.

I am using a heavy cart, made of 60mm t-slot extrusions, as a base. There is very little traffic where I am.

I am going to attach a vertical column to which I can mount the camera. One of the configurations will be camera pointing down at an optical breadboard. Should the breadboard be fastened to the same structure that holds the camera, or would it be better to float it on Sorbothane?

ray_parkhurst
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Re: Subject Coupled-to or Isolated-from Camera?

Post by ray_parkhurst »

Doppler9000 wrote:
Wed Sep 01, 2021 12:06 pm
I am working on my studio design.

I am using a heavy cart, made of 60mm t-slot extrusions, as a base. There is very little traffic where I am.

I am going to attach a vertical column to which I can mount the camera. One of the configurations will be camera pointing down at an optical breadboard. Should the breadboard be fastened to the same structure that holds the camera, or would it be better to float it on Sorbothane?
Make it as tightly-coupled between camera and subject as possible. You want the two to have very fast settling times when external shocks are applied. Any sorbothane or other dampening methods should attempt to isolate the subject+camera system from outside influence.

One of the biggest problems you might face is lens-camera coupling. The objective end of the lens will usually not be well-coupled to the camera mount, so that it can move relative to the subject. This is to be avoided. Often some mechanical support for the lens is needed to keep it well-coupled vs the camera+subject.

The advice above applies more critically for continous lighting. For flash, you can get away with less coupling.

Lou Jost
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Re: Subject Coupled-to or Isolated-from Camera?

Post by Lou Jost »

Doppler9000, does your camera have a mirror?

Doppler9000
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Re: Subject Coupled-to or Isolated-from Camera?

Post by Doppler9000 »

Lou Jost wrote:
Wed Sep 01, 2021 8:06 pm
Doppler9000, does your camera have a mirror?
No mirror and I will use electronic shutter.

Adalbert
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Re: Subject Coupled-to or Isolated-from Camera?

Post by Adalbert »

Hello Doppler9000,

That's an interesting story with the vibrations.

When I started with macro photography, I also thought about it.
At some point I happened to notice that the external vibrations don't do much damage.
But the internal vibrations caused by the camera or the rail do.
That's why I got myself a camera with a fully electronic shutter and take a short break after moving the rail so that the vibrations can subside.
I have also noticed that the vibrations last longer with the heavy metal setups and tend to resonate.
Light setups, on the other hand, settle down more quickly.
It also makes sense to combine different materials, e.g. wood and aluminium.

Of course, these are my personal observations.
Absolutely subjective and certainly not universally valid :-)

Best, ADi

ray_parkhurst
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Re: Subject Coupled-to or Isolated-from Camera?

Post by ray_parkhurst »

Adalbert wrote:
Thu Sep 02, 2021 9:45 am
...
I have also noticed that the vibrations last longer with the heavy metal setups and tend to resonate.
Light setups, on the other hand, settle down more quickly.
It also makes sense to combine different materials, e.g. wood and aluminium.

Of course, these are my personal observations.
Absolutely subjective and certainly not universally valid :-)
...
Valid observations are the core of science, so no reason to downplay them. Our knowledge of the world is very limited, especially for any given individual, so when we run up against a question that we don't know the answer to, experimentation and observation is the best way to move forward, certainly better than serendipity.

Your observations pointing toward lightweight setups matches my experience as well. Light weight means fast settling time. Using wood in the setup also makes sense since wood has good stiffness to weight ratio, and excellent internal dampening.

Doppler9000
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Re: Subject Coupled-to or Isolated-from Camera?

Post by Doppler9000 »

ray_parkhurst wrote:
Fri Sep 03, 2021 6:39 am
Adalbert wrote:
Thu Sep 02, 2021 9:45 am
...
I have also noticed that the vibrations last longer with the heavy metal setups and tend to resonate.
Light setups, on the other hand, settle down more quickly.
It also makes sense to combine different materials, e.g. wood and aluminium.

Of course, these are my personal observations.
Absolutely subjective and certainly not universally valid :-)
...
Valid observations are the core of science, so no reason to downplay them. Our knowledge of the world is very limited, especially for any given individual, so when we run up against a question that we don't know the answer to, experimentation and observation is the best way to move forward, certainly better than serendipity.

Your observations pointing toward lightweight setups matches my experience as well. Light weight means fast settling time. Using wood in the setup also makes sense since wood has good stiffness to weight ratio, and excellent internal dampening.
I was thinking about a stout (heavy) aluminum extrusion, mounted vertically, to hold the camera.

Should I consider a wood column?

PeteM
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Re: Subject Coupled-to or Isolated-from Camera?

Post by PeteM »

A few notions of structural design:

- Know -- and eliminate as far as possible -- sources of vibration (touching the camera, shutters, mirrors, stepping motor vibrations, cars passing by, etc.).

- Mass isn't bad as long as its devoted to damping. You just don't want to get it moving -- or it will keep wanting to move. Mass in the base - probably OK. Mass hanging out in space - not so good. FWIW, aluminum generally has a higher stiffness to weight ratio than wood.

- Design the structure so that its resonant frequencies aren't excited by any remaining sources of vibration. With low frequency inputs, a stiff structure (say, welded aluminum trusses) will have a naturally high frequency and be a good choice. With high frequency inputs it might act more like a tuning fork.

- Use damping materials to try to minimize what's left. For machine tools it might be supporting structures made of cast iron rather than steel. For microscope tables it might be a mat under the rig rather than a solid connection through the table to the floor.

I'd think a stiff aluminum structure, with near zero internal vibrations (no mirror, no shutter, no hands, some time between steps) plus the whole rig isolated from external vibration would do just fine.

Adalbert
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Re: Subject Coupled-to or Isolated-from Camera?

Post by Adalbert »

Hi Doppler9000,
Should I consider a wood column?
I don't want to recommend anything but I can only show how I implemented my idea:
https://www.facebook.com/photo/?fbid=12 ... 0269581589
Best, ADi

ray_parkhurst
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Re: Subject Coupled-to or Isolated-from Camera?

Post by ray_parkhurst »

Adalbert wrote:
Fri Sep 03, 2021 12:28 pm
Hi Doppler9000,
Should I consider a wood column?
I don't want to recommend anything but I can only show how I implemented my idea:
https://www.facebook.com/photo/?fbid=12 ... 0269581589
Best, ADi
You have a fairly large moment about the single mount to the linear rail. I have found great improvement in reducing this moment through the use of an idler rail. I am working with another forum member on a method to add such an idler rail to an existing system that utilized a StackShot by mounting the idler to a 90-deg mount attached to the motor. It should work beautifully, but could also benefit from additional mounting to the base which holds the linear rail. It's a similar concept to what I've done in my own systems, essentially eliminating the "pitch" and "yaw" moments. "Roll" is still present, but there is only a small moment in the roll and yaw directions, only in pitch.

ray_parkhurst
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Re: Subject Coupled-to or Isolated-from Camera?

Post by ray_parkhurst »

Doppler9000 wrote:
Fri Sep 03, 2021 11:16 am

I was thinking about a stout (heavy) aluminum extrusion, mounted vertically, to hold the camera.

Should I consider a wood column?
I would not hesitate to recommend what I do for coin photo systems: extruded aluminum column with wood base. Whatever stage you desire (Z, XY, R, goiniometers, etc) can be mounted easily to the wood base, while the automated linear rail can be mounted (with an idler) to the aluminum column.

I mount the column to the base with a long bolt which extends from top of column down through the wood base, with nuts on each end.

Adalbert
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Re: Subject Coupled-to or Isolated-from Camera?

Post by Adalbert »

Hi Ray,
I mount the column to the base with a long bolt which extends from top of column down through the wood base, with nuts on each end.
something like that?
rail_1024.jpg
BTW, could you please show a picture of the solution with the idler rail?
Thank you in advance.
Best, ADi

ray_parkhurst
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Re: Subject Coupled-to or Isolated-from Camera?

Post by ray_parkhurst »

Adalbert wrote:
Sat Sep 04, 2021 4:04 am
Hi Ray,
I mount the column to the base with a long bolt which extends from top of column down through the wood base, with nuts on each end.
something like that?
...
BTW, could you please show a picture of the solution with the idler rail?
Thank you in advance.
Yes, just like that. Works beautifully to hold it all together.

Below is info for a horizontal setup I built for a forum member, with concept drawing first, then finished system. Finished system is slightly different in the feet and subject holder but the rail part is very close to the concept drawing, and shows the integration of the idler rail very clearly. In more recent systems I have flipped the idler so that its rail is bolted to the moving (upper) Arca Plate, and carriage to the fixed Plate. There are arguments for both implementations, and the jury is still out.
.
Edited to add: the whole system is held together with a single long bolt.
.
Horizontal with Idler4.JPG
.
Horizontal with Idler3.JPG
.

Adalbert
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Re: Subject Coupled-to or Isolated-from Camera?

Post by Adalbert »

Hi Ray,

Many thanks!

But what about the THK with 2 blocks ?
As for example: Model KR-B (with Two Long Type Blocks)
https://tech.thk.com/en/products/pdf/en_a02_074.pdf

Best, ADi

ray_parkhurst
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Re: Subject Coupled-to or Isolated-from Camera?

Post by ray_parkhurst »

Adalbert wrote:
Sat Sep 04, 2021 7:17 am
But what about the THK with 2 blocks ?
As for example: Model KR-B (with Two Long Type Blocks)
https://tech.thk.com/en/products/pdf/en_a02_074.pdf
The "B" rails are good if you only need relatively short movements. I have a few of them, though have never been successful at integration because I need more adjustability in heights and extensions than they offer. Reason for this is the more distance you make between the rails, the less movement you get. You can of course get a longer rail, but all the ones I've seen are quite expensive. It's much easier, more flexible, and cheaper to go with the idler approach.

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