[pure-silver] Re: Contrast paper developer
- From: İbrahim Pamuk <ibrahim.pamuk@xxxxxxxxxxxxx>
- To: <pure-silver@xxxxxxxxxxxxx>
- Date: Mon, 20 Aug 2007 22:37:12 +0300
Your are right. It is also true that my negative quite grainy when I complaint
about contast. They are a little over exposed infared negatives. I plan to go
back to my old condenser enlarger.
regards
Ibrahim Pamuk
-----Original Message-----
From: pure-silver-bounce@xxxxxxxxxxxxx
[mailto:pure-silver-bounce@xxxxxxxxxxxxx] On Behalf Of Richard Knoppow
Sent: Thursday, August 16, 2007 12:23 AM
To: pure-silver@xxxxxxxxxxxxx
Subject: [pure-silver] Re: Contrast paper developer
De: Ä°brahim Pamuk <ibrahim.pamuk@xxxxxxxxxxxxx>
Date: Wed, 15 Aug 2007 11:54:01 +0300
Sujet: [pure-silver] Re: Contrast paper developer
À: <pure-silver@xxxxxxxxxxxxx>
>Hi,
Just one more question, I suppose your condenser enlarger uses a tungsten bulb
and your diffused enlarger a halogen bulb, am I right ?
Good luck,
Claudio Bonavolta
I don't thin this would make much difference.
Tungsten-halogen lamps generally run at about the same temperature as plain
tungsten. Tungsten enlarging lamps generally are around K3000. The color
temperature of household tungsten lamps varies with the wattage but is around
K2950 on average. Standard lamps for color photography are K3200. Photoflood
lamps are around 3400 but get this high temperature because they are run
overvoltage and have very short lives.
AFAIK, no color enlarger has other than tungsten lamps. A cold light lamp,
particularly the older very blue variety, will seriously limit the range of
contrast available with variable contrast paper even when a yellow correction
filter is used.
The difference in printing contrast between a diffuse source, such as a
color head with a mixing chamber, and a partially diffusing condenser enlarger,
such as the typical Omega or Besler, is about one paper grade, but this also
depends a bit of the grain of the negative. For instance, color negatives have
virtually the same contrast for both types of sources. The difference in
contrast comes from the scattering of light by the silver particles, the
coarser the grain the greater the scattering. This is known as the Callier
effect.
---
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx
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