Enlarger lens focal length and image size?

BradS · Aug 10, 2008

Please explain how the projected image size is related to the focal length of the enlarger lens.

MattKing · Aug 10, 2008

The shorter the focal length, the larger the projected image size.

It works the same way with projectors of any type.

One tends to use a focal length that is approximately equal to the diagonal of the negative, but there are so called "wide angle" enlarger lenses that have shorter focal lengths (with the accompanying greater enlargement) but still cover negatives with a larger diagonal.

Matt

richard ide · Aug 10, 2008

I would add that the projected size is related to the magnification factor. The restrictions of bellows length, focal length and coverage of the lens and maximum distance available from lens to enlarging paper all have to be taken in to account. A horizontal enlarger eliminates the restrictions you have with a vertical enlarger.

BradS · Aug 10, 2008

MattKing said:
The shorter the focal length, the larger the projected image size.Matt

Ah, good. I haven't drunk too much wine.

I just "upgraded from a 135mm Omegaron to a 150mm Componon-S and I noticed that at the same height, the 150mm lens appeared to give a smaller image!

This is of course, exactly the opposite of what I expected for some reason.

So, does any body know what cone to use with a 150mm lens on an omega D-2?

bdial · Aug 11, 2008

From Harry Taylor at Classic-enlargers.com...

Only the lenses used for 4x5 use cones and the the 135mm requies a
2 3/4" cone, while the 150mm uses a 4 1/2" cone.

http://www.classic-enlargers.com/cgi-bin/yabb/YaBB.pl?num=1099503384/1

BradS · Aug 11, 2008

Ah, very good. Thank you. I had the 150mm on the 2-3/4 inch cone. Which works ok but, requires more bellows draw.

Enlarger lens focal length and image size?

BradS

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