[pure-silver] Re: Optical question

No difference if before the lens.
If after the lens, I think the image is formed closer to the lens by 1/3rd the thickness of the acrylic, depending on the refractive index of the acrylic, if my optics memory serves me (and that was a long time ago). 

...Vick

Peter De Smidt wrote:
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? If so, would there need to be more or less extension between the negative and the lens? ============================================================================================================= 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. 


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