[pure-silver] Re: donut solution; enlarger lens problem
- From: Georges Giralt <georges.giralt@xxxxxxx>
- To: pure-silver@xxxxxxxxxxxxx
- Date: Sat, 12 May 2007 08:41:13 +0200
Hi Shannon !
Shannon Stoney a écrit :
I see what you mean. I always print emulsion side down like everybody
else. (With my scanner you have to do the opposite.)
Why is that ? Maybe you will need a custom film carrirer making the base
of the film a few mm above the glass...
So if I had the
base side up and the frosty glass on top, I was doing it right. To tell
the truth, I'm not sure how I had it, and I'm not near my darkroom now
so I can't check. I think I remember it was on top.
Why is it that frosting only affects the optical quality if you put it
on the bottom? It would seem that it would affect the image whether
it's on top or bottom. But the prints looked sharp, to me.
Frosting a glass make it a diffusing material. Lock at white perspex or
plexiglass and compare it to transparent plexiglass. This is the last
step in frosting. It perfectly diffuse the light so one can't look trouh it.
So now, immagine the image which goes out the negative trying to get
through the diffusing effect of the frosted glass before hitting the
lens.....
When you put the frosted glass above the negative, you only diffuse the
light which will strike the negative. Not the image.
Hope I'm making it clear ;-)
--shannon
On May 11, 2007, at 3:56 PM, Georges Giralt wrote:
Shannon Stoney a écrit :
Are Newton rings really named after Isaac Newton? If so, why?
--shannon
Because he discovered the phenomenom and described it.
Newton rings appear when two perfectly matching surfaces are in close
contact. (being flat or not, it is sometimes used to control lens
curvature)
--
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