[LargeFormat] Macro depth of field

[Ole Tjugen]

22.01.03 11:57:21, "Mike Finley" <mike@efikim.freeserve.co.uk> wrote:

<snip>
>
>There are then two things affecting depth of field (assuming same lens and
>aperture):
>I can use a larger circle of confusion on the 5x4 negative, as it won't be
>enlarged as much, increasing depth of field.
>I am shooting at a higher magnification on the 5x4 (1.5x rather than 0.75x),
>decreasing depth of field.
>
>I think, from looking at a couple of negatives, that the latter has greater
>effect, giving me overall less depth of field with 5x4 film than a roll-film
>back, assuming the same aperture. I haven't tested this properly though.
>
>Can anyone confirm this?
>
>thanks,
>mike
>

In one word: Yes.
The reproduction ratio ON THE FILM determines DOF - that's why "cheap" consumer digital cameras have too much DOF to be usable for 
macro.

Using the same ratio at the same aperture, DOF is the same regardless of film type and size - as well as lens focal length!

Ole