How stack focus with analog?

[jtk]

analog stack focus, e.g. insects.
Powerful and relatively easy with PS..even possible without? Links?

 

[jim10219]

Scientists used to do it in the old film days all of the time. They did it in camera. There's a name for it, but I don't remember the name.

The idea is pretty simple. You take a stationary small sliver of light in a dark room and move your subject through that, usually done in small steps with a single exposure taken at each step, as part of a multiple exposure. To make the sliver of light, they often used lasers or collminated light passes through a slit filter. A common technique that would probably work well for standard macro photography is to place three projectors, one left, one right, and one above the subject. In place of the slide, place a mask with a slit so that the slita of light line up parallel to the film plane (perpendicularl to the angle of the lens). The camera is focused at that point and held steady at a fixed point, so the camera never moves. A single exposure is taken, and the subject which is mounted on a track, is moved forward or backward to expose the next section adjacent to the previous exposure. Step and repeat until the entire object has passed through the slit of light.

It takes some special equipment and some patience and careful planning to expose the film, but once the exposures are made, the developing and printing are standard.

 

[glbeas]

It has been done in a broad manner in dark and lowlight situations where you can paint with light. The one situation that comes to mind for me is cave photography in a large room. Its possible to illuminate an area, then shift focus for another area and illuminate it, and so on You do have to be careful and aware of any overlaps in exposed areas though some small amount may not be noticeable.

 

[jtk]

Great responses !
They remind me of an assignment I did for Chevron Chemical...a Kodachrome of the giant engine room of an oil tanker...one multi-exposed frame (and a few almosts) using Canon F1 and Viv 283 courtesy of Minolta flash meter and ridiculous confidence.

 

[AgX]

It was done with a light curtain. And the object on a precision slide.