[pure-silver] Re: Durst L1200 (condensor) & uneven illumination
- From: Martin Jangowski <martin@xxxxxxxxxxxx>
- To: pure-silver@xxxxxxxxxxxxx
- Date: Mon, 23 Jul 2007 12:18:01 +0200 (CEST)
On Mon, 23 Jul 2007, C.Breukel@xxxxxxx wrote:
The best I could do is roughly the following:
0.15 0.08 0.16
0.08 0.00 0.07
0.17 0.06 0.12
(so the middle put on zero, the other figures representing the very
corners and sides). Initially I mistrust the Zonmaster, I mean 0.1 means
1/3 stop and 0.15 1/2 a stop.
I find this alot, OTOH I never realy noticed this when printing
(probably tells that I am not that a good printer I guess..
These are excellent values! You omitted one information: what f-stop did
you use for your tests?
Compare the light-falloff diagram of the 4/80mm Rodagon with your values:
http://www.butzi.net/rodenstock/rodagon/80mm.htm
You'll see that the Rodagon looses more than 1/2 stop at the edges when
used at the optimum stop, more when used wide open (nearly 2 complete
stops at f4 and 44mm away from the center!) This is completely normal, you
won't find another lens with (much) better values.
Don't forget that your camera lenses have light-falloff at the edges,
too.... these lighter edges (with a normal negative-positive process)
compensate a lot of the light falloff of the enlarger lens. The guys with
positive-positive processes have a lot more problems, here both effects
are additive...
Grüße aus Hohenlohe,
Martin Jangowski
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