From: "Peter De Smidt" <pdesmidt@xxxxxxx>
Suppose one were to put a piece of 5mm thick acrylic between a negative and an enlarging lens. Would the piece of acrylic cause the distance needed to focus the negative at a given size to change?
Yes.
If so, would there need to be more or less extension between the negative and the lens?
More ... the negative will appear 'closer' to the lens and so you will need to move the lens farther away to compensate. With thin filters, and distant objects, there is less focusingoffset if the filter is on the film side of the lens, but there is still an effect.
Obviously, at 1:1 the effect is equal on both sides. -- Nicholas O. Lindan Cleveland Engineering Design, LLC Cleveland, Ohio 44121 ============================================================================================================= To unsubscribe from this list, go to www.freelists.org and logon to your account (the same e-mail address and password you set-up when you subscribed,) and unsubscribe from there.