[pure-silver] Re: lens for enlarging 8x10?
- From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
- To: <pure-silver@xxxxxxxxxxxxx>
- Date: Mon, 14 Feb 2005 16:49:26 -0800
----- Original Message -----
From: "Howard Efner" <hfefner@xxxxxxxxxxxxx>
To: <pure-silver@xxxxxxxxxxxxx>
Sent: Tuesday, February 15, 2005 2:31 PM
Subject: [pure-silver] Re: lens for enlarging 8x10?
> Shannon, I have used a 240mm f/9 Nikkor M process lens for
> 8x10
> enlarging. The shorter focal length keeps the distances
> more reasonable
> than what you need for a 300. With a 300 at 1:1, you need
> a film-to-paper
> distance of about 4 ft., and it only gets worse as you go
> to bigger prints.
>
>
The trade off is uniformity of illumination. The narrower
the coverage of the lens (longer the focal length) the more
uniform the illumination will be. This has to be balanced
against the reduction in head height to make a given size
print.
Since the image circle of a lens depends on magnification
a relatively short lens will have enough coverage for low
magnification enlarging. At 1:1 a lens has double the image
circle it has at infinity. This is a different issue than
uniformity.
Before specialized enlarging lenses became available the
most often used lenses for large enlargers were process
lenses like the Artar. For 8x10 the magnification is within
the optimum range of most of these.
---
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx
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