Hello:

Someone here gave an interesting suggestion regarding having a grid lamp
made up that was blue.

I don't remember what that was a solution for, but it sounds like it's worth
exploring for my big monochromatic lens.

I have conflicting wavelength info I will clarify first. What needs to be
resolved is whether the light source used was 436 nm mercury-xenon, or 560
(actually double line at I think 544 and 577 nm +/-). The first is
blue/violet; the second I think is greenish.

Assuming I get the right info, I am curious what will be the effect on
contrast of using a narrow spectrum light source in an enlarger.

Also, I read a white paper that came from the Schneider Optics site about
lens resolution vs. contrast. This was mostly related in terms of spatial
frequency which is a step further toward abstraction and a step further away
from understanding what it means. It sounds like high resolution lenses have
low contrast and vice versa; one design choice among many.

Now, whether this means the same thing as the topic of comparing contrast
between coated and uncoated lenses. I saw someone's opinion that single
coated was more pleasing than multi-coating when dealing with shadows (???).

Can someone explain the visual effect of these concepts?


Meanwhile, I'm exploring light sources...also have to look at Huw's LED
enlarger using mega-LED's (Luxeon?). It appears that the 436 nm Hg-Xe lamps
have a huge amount of UV, too. There are smaller ones up to 200 W that don't
require forced air cooling - just ugly power supply requirements.

Murray


Thanks


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