Subject mover horizontal setups - lighting?

[ChrisLilley]

Preamble - I have been using a camera-mover setup, sometimes horizontal and sometimes vertical. Tripod and ballhead holds Stackshot, which holds bellows and moves; subject is placed on a tabletop (for vertical setup) or on some (rickety) support (for horizontal setup) and flash units are also fixed to the table. So, the lighting is fixed relative to the subject.

This setup is sort of ok but rather high and I was wondering about a lower, horizontal setup. Stackshot sits on some sort of base rail and holds subject; bellows sits on the same base rail facing it, and does not move. But now, the lighting is not fixed relative to the stacking motion.

I assume that either
a) this does not matter, and people with subject-mover setups have diffuse lighting that can cope with a cm or so of relative subject-light movement over the course of a stack; or
b) it does matter, so people with subject-mover setups also have flash arms or something attached to the subject stage. Which seems to somewhat take away from the 'subject movers shift less mass' argument.

I haven't found any setups on the forum with subject movers that also hold lighting (and few with subject movers, in fact).

I would be glad of pointers to other setups, or comments, or people explaining why I have it all wrong

[rjlittlefield]

I think you have it right and the answer is mostly (a).

There are some specialized situations where it can be a problem if the subject moves and the light doesn't. One is if you're shooting stereo as two stacks. See "Stereo Pairs: the effect of lighting shifts" for an example of what can happen there if the subject rotates and the lighting doesn't. Another is if you're shooting a macro panorama, you don't want the subject to move sideways while the lighting doesn't.

But other than those two, I think it's mostly a matter of ergonomics and mechanics.

The tradeoffs change over time. When all I had was an optical viewfinder, it was really important that I be able to run all the positioning controls while staring into the viewfinder. Now with electronic output to a monitor or computer, that's not so much of an issue. Likewise with the stereo. When the only way I could shoot stereo was with a physical rotation, it was a lot easier to move the camera than the subject & lights. But since Zerene got synthetic stereo, I haven't needed to do any physical rotation so moving the subject would have been fine.

If I were designing from scratch today, I might very well decide to do my horizontal rig by bolting the camera to a big chunk of mass and doing all movements on the subject side.

--Rik

[microcollector]

Those who do lots of micro mineral photography seem to favor having the lights maintain their position with respect to the subject. When shooting transparent crystals with internal flaws, one can get some strange results if the lights are changing position. That said, there are those that do move the subject instead of the camera. My change from shooting through the microscope to using a horizontal set up and moving the camera was partly driven by this.

Doug

[AndrewC]

Doug's post reflects (no pun intended) my own thoughts on this, namely if you have any kind of reflection / refraction going on it seems best to keep the lighting / subject alignment the same and step the camera. Then again if your light source is diffuse and large compared to the subject it should not matter as much if at all.

My first bench had the option of moving either subject or camera and I got some weird results when moving the subject.

[ChrisLilley]

I haven't found any setups on the forum with subject movers that also hold lighting (and few with subject movers, in fact).

A stackshot-based subject-mover with fixed lighting and camera setup has now been posted by tonygt19.