[LargeFormat] Macro photography and movements

[Paul Butzi]

> However, at 1:1 magnification the point of focus to film distance is
> at a minimum for conventional cameras. Whether you increase or
> decrease .or the lens to film distance, the focus point moves further
> away from the film. Its this that makes me wonder what happens on a
> large format camera.


I don't understand.  On any camera with a lens that has a fixed focal length
(e.g. no moving internal elements that change focal length as you focus),
increasing the lens to film distance DECREASES the lens to subject distance,
as described by the lens rule:
	(1/f) = (1/v) + (1/u)
Where f is the focal length and v and u are the lens to film and lens to
subject distances.

When u = f and v = infinity, you are focused at infinity and the bellows
extension is the shortest it can be and have something in focus - focus is
at infinity.  As you increase the bellows extension (increase the lens to
film plan distance) the distance to the subject in focus decreases.  When u
= v = (2 * f) you have the bellows extended to twice the focal length, the
lens to subject distance is twice the focal length, and the magnification is
1:1.  If you increase the bellows extension from that point, you continue to
decrease the lens to subject distance and increase magnification.

No matter what magnification you start with, increasing the lens to film
distance will always increase magnification and shorten the lens to subject
distance.

At no point is it possible to move the film farther away from the lens and
increase the lens to subject focus distance.

-Paul