Compatible Cold light heads for Omega D5V

"Lew" wrote in message
...
Can anyone give me a run down of what's available, what to
look at &
what to avoid? Thanks.

Since others have given you some answers I will ask a
question: Why do you want to change to a cold-light head?


--
Richard Knoppow
Los Angeles, CA, USA

Richard Knoppow wrote:
"Lew" wrote in message
...
Can anyone give me a run down of what's available, what to
look at &
what to avoid? Thanks.

Since others have given you some answers I will ask a
question: Why do you want to change to a cold-light head?

I would like to know as well. I'm rebuilding a Saltzman 8x10 with
condensers. I know that four 250W bulbs is going to be hot, but such has
a reliable on/off quality of light. Cold heads - dunno - they seem so
finnicky - someone enlighten me.

john joseph wrote:
Richard Knoppow wrote:
"Lew" wrote in message
...
Can anyone give me a run down of what's available, what to look at &
what to avoid? Thanks.

Since others have given you some answers I will ask a question:
Why do you want to change to a cold-light head?

I would like to know as well. I'm rebuilding a Saltzman 8x10 with
condensers. I know that four 250W bulbs is going to be hot, but such has
a reliable on/off quality of light. Cold heads - dunno - they seem so
finnicky - someone enlighten me.

*waves wand* I pronounce you enlightened....as if my opinion really mattered (been married
too long to think otherwise)


I think most people want to go to a diffused light source to minimize the dust and scratch
issue. Personally, I lean towards the flourescent bulb and white diffusor approach, which
reminds me, John, you wanna let go of that electromagnetic (solenoid actuated) shutter
from the enlarger?

back to the subject at hand, if you know a good (I mean really good) neon bender, a
coldlight head is not much more than a neon tube bent in a serpentine pattern. I bent one
up (years ago) for a friend that had vertical returns and had 1/2" spacing, used a bit of
glass up, but worked wonderfully. It's really important to ask you bender to bombard the
glass properly, most glass guys just seem to do good enough, as opposed to allowing all
the contaminants to be burnt off before pumping the glass down. I could probably look up
the specifics if anyone is interested, I may have my notes still.

e

erie patsellis wrote:
john joseph wrote:
Richard Knoppow wrote:
"Lew" wrote in message
...
Can anyone give me a run down of what's available, what to look at &
what to avoid? Thanks.

Since others have given you some answers I will ask a question:
Why do you want to change to a cold-light head?

I would like to know as well. I'm rebuilding a Saltzman 8x10 with
condensers. I know that four 250W bulbs is going to be hot, but such
has a reliable on/off quality of light. Cold heads - dunno - they seem
so finnicky - someone enlighten me.

*waves wand* I pronounce you enlightened....as if my opinion really
mattered (been married too long to think otherwise)


I think most people want to go to a diffused light source to minimize
the dust and scratch issue. Personally, I lean towards the flourescent
bulb and white diffusor approach, which reminds me, John, you wanna let
go of that electromagnetic (solenoid actuated) shutter from the enlarger?

If you mean the one I diagramed, then sure. It won't work at all with my
timer. It is in pieces now. I think you have my email address. Write and
I'll try to make it so.


back to the subject at hand, if you know a good (I mean really good)
neon bender,[...]

Funny you should ask. I DID know one but he fell deeply into alcoholism
twenty years ago and is good for nothing now except some good story
telling - over and over and over. No benders anywhere near here.

"john joseph" wrote in message
m...
Richard Knoppow wrote:
"Lew" wrote in message
...
Can anyone give me a run down of what's available, what
to look at &
what to avoid? Thanks.

Since others have given you some answers I will ask
a question: Why do you want to change to a cold-light
head?

I would like to know as well. I'm rebuilding a Saltzman
8x10 with condensers. I know that four 250W bulbs is going
to be hot, but such has a reliable on/off quality of
light. Cold heads - dunno - they seem so finnicky -
someone enlighten me.

Cold lights are not really finnicky but they are
fluorescent lamps and, like all gaseous discharge lamps, the
output varies with temperature increasing with increasing
temperature. While some Aristo models have heaters to even
out the output most lamps of this sort like to run hot and
run continuously.
Cold light has had all sorts of magical qualities
attributed to it. For the most part they are not so. A cold
light head is a diffusion head but so are many other kinds
of heads such as most color heads and the original Saltzman
head for that matter. For black and white silver negatives
the diffusion source produces about one paper grade less
contrast than the usual condenser head which focuses a
large, diffuse, lamp on the negative. There is no difference
in tone rendition between a condenser and diffusion source
provided that the overall contrast is compensated for either
in the print material or the negative.
Diffusion heads also tend to suppress negative
blemishes of some types but this is often illusory since the
harder grade of paper needed will tend to pick up the
blemishes again. It _does_ make a difference in color
printing where the _Callier Effect_, which is what is
responsible for the contrast difference, is very slight.
That is, a color negative or transparency will have about
the same contrast on a diffusion or condenser source.
True point sources tend to produce somewhat greater
resolution but, for the usual condenser type enlarger
source, there is no detectable difference in resolution
between the two types.
A properly designed and adjusted condenser source will
have just as uniform illumination as a good diffusion
source, including cold light sources. There is really very
little to choose between them. However, for small negatives
the condenser may allow shorter exposure times because its
light is concentrated.
I have both the original condenser source and an Arista
cold light source for my Omega D2v. I think I originally
bought the cold light because I was getting uneven
illumination. I was able to make good prints using it,
especially from 4x5 negatives. But, I eventually discovered
that the enlarger was considerably out of alignment and,
once aligned, the condenser had better uniformity of
illumination than the cold light head. For that reason and
some others, I switched back and have never gone back to the
Arista.
The D5v has a better method of adjusting the focus of
the condenser system than the D2V and should produce even
better results.
Now, the original poster may have other reasons for
wanting to switch, or perhaps the condenser head is missing.

--
Richard Knoppow
Los Angeles, CA, USA

Richard Knoppow wrote:
"Lew" wrote in message
...
Can anyone give me a run down of what's available, what to look at &
what to avoid? Thanks.

Since others have given you some answers I will ask a question: Why do
you want to change to a cold-light head?

Richard's implied suggestion is a wise one. All manner of magical properties
are ascribed to cold light heads.

The most important one is supposedly that you can use it to print negatives
that are unprintable otherwise because their contrast is too great. Of
course, that should seldom arise because you calibrated your exposure,
developing, etc., to your existing enlarging system already, right? So if
your negatives have excessive contrast to print even on the softest grade
paper, you mane a serious mistake in exposure, or development. Picker seemed
to feel that exposing and developing for (IIRC) grade 3 paper and printing
with a cold light gave better quality prints than exposing and developing
for grade two paper and printing with a condenser head. But as Dr.Richard J.
Henry proved, the two will have identical D/H curves. So this argument turns
out to be of no validity. A cold light head will be helpful in controlling
contrast only for those who overdevelop their negatives. It was my
impression that people used to underexpose their negatives (they thought
they were increasing the speed of the film), and over develop them to
maintain contrast in the mid tones (only to get burned out highlights). But
if you calibrate your film, you will get the best speed of which the film is
capable (but not 800 from Tri-X; probably not even 400).

The next most important claim is that with diffuse illumination, dust and
other defects of the negatives simply disappear. This turns out to be
nonsense. Picker's most important cure for this problem is not his (or
anyone else's) cold light head, but his negative cleaning brush, the one
with a 5000 volt neon sign transformer that produces a corona near the
bristles of the brush with which you wipe the dust off the negative. A cold
light head lowers the contrast of your print by about one contrast grade
compared with what you would get if you used a condenser head. But then you
have to use a grade harder than the condenser head required to get the
proper contrast, and the dust and scratches are back. Sorry, the only good
solution is to keep your negatives clean, or to clean them.

As far as I can tell, the only reason to use a cold light head is that it is
somewhat cooler than the typical condenser head. This can reduce the risk of
the negative's popping between when you focus it on your paper and when you
actually make the print. I have never had this happen, but I do not doubt it
can happen, especially with small negatives (e.g., 35mm). It does not happen
for me with 4x5" negatives because I use Beseler's Negaflat (I call it their
nega-stretch) film carrier there that puts the film under slight tension so
it must be flat. Others call it their nega-scratch carrier because it tends
to scratch the extreme edges of the negative. I do not compose my images
quite that close to the edge of the image area, so it does not bother me.
For other sizes, you might consider using glass holders (I forget what they
are really called: the ones where the film is held between two pieces of
glass) that should also keep them flat.

If you get a cold light head with two tubes, a blue one and a green one, you
will not need to bother with variable contrast filters to get the contrast
grade you need (if you use variable contrast paper). You just dial in the
amount of blue and green you need to get the contrast you want. I find this
a convenience, but a color head would do the same thing. Aristo still make
these, and Zone VI used to. The main troubles with the Zone VI are that the
thing is not really bright enough, though it is definitely usable; and that
the green tube has to be warmed up considerably to get the regulator to keep
it stable, which is annoying. I hope that the Aristo does not suffer from
this problem.

--
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