Zone VI cold light head

There's a decent looking Beseler 23 series with a cold light head on
Craigslist.

I've read that one needs to do additional filtration on the cold light
heads. Is that true? If so, what type of filter?

Thanks,
Greg

"G.T." wrote in message
...
There's a decent looking Beseler 23 series with a cold
light head on Craigslist.

I've read that one needs to do additional filtration on
the cold light heads. Is that true? If so, what type of
filter?

Thanks,
Greg

There are two kinds of lamps used in cold-light heads,
one is very blue and is not really compatible with variable
contrast paper although it can be used. The other lamp has a
color similar to a tungsten lamp and will work with VC. The
first type needs a yellow filter. Even with that the range
of contrast available with VC filters will be limited. The
second type of lamp will work with VC filters but also will
have some limititation on the range of contrast available.
Paper data sheets will usually have a recommended filter for
use with cold light heads.
Almost all of these heads are made by Arista who may
also have some recommendations and will have replacement
lamps. You can replace the blue type lamp with the tungsten
type. I don't know the cost.


--
---
Richard Knoppow
Los Angeles, CA, USA

"Richard Knoppow" wrote in message
...

"G.T." wrote in message
...
There's a decent looking Beseler 23 series with a cold light head on
Craigslist.

I've read that one needs to do additional filtration on the cold light
heads. Is that true? If so, what type of filter?

Thanks,
Greg

There are two kinds of lamps used in cold-light heads, one is very blue
and is not really compatible with variable contrast paper although it can
be used. The other lamp has a color similar to a tungsten lamp and will
work with VC. The first type needs a yellow filter. Even with that the
range of contrast available with VC filters will be limited. The second
type of lamp will work with VC filters but also will have some
limititation on the range of contrast available. Paper data sheets will
usually have a recommended filter for use with cold light heads.
Almost all of these heads are made by Arista who may also have some
recommendations and will have replacement lamps. You can replace the blue
type lamp with the tungsten type. I don't know the cost.


Thanks for the info. I'm going to pass on that one.

But I've pretty much decided to start printing at home so I'm on the
lookout, probably for a 23 series since it's the one I'm most familiar with.

Greg

"G.T." wrote in message
...

"Richard Knoppow" wrote in
message ...

"G.T." wrote in message
...
There's a decent looking Beseler 23 series with a cold
light head on Craigslist.

I've read that one needs to do additional filtration on
the cold light heads. Is that true? If so, what type
of filter?

Thanks,
Greg

There are two kinds of lamps used in cold-light heads,
one is very blue and is not really compatible with
variable contrast paper although it can be used. The
other lamp has a color similar to a tungsten lamp and
will work with VC. The first type needs a yellow filter.
Even with that the range of contrast available with VC
filters will be limited. The second type of lamp will
work with VC filters but also will have some limititation
on the range of contrast available. Paper data sheets
will usually have a recommended filter for use with cold
light heads.
Almost all of these heads are made by Arista who may
also have some recommendations and will have replacement
lamps. You can replace the blue type lamp with the
tungsten type. I don't know the cost.


Thanks for the info. I'm going to pass on that one.

But I've pretty much decided to start printing at home so
I'm on the lookout, probably for a 23 series since it's
the one I'm most familiar with.

Greg
I am not a particular fan of cold light heads. Several
years ago I bought one for my Omega D2v but went back to the
condenser head before long. I got good results from the cold
light head but it was no better than the condenser and,
after a careful alignment, no more uniform plus I prefer the
tungsten source when I am using VC paper (which is most of
the time). The cold light does give more light output for
4x5 negatives and is useful in printing very dense ones but
that is a rare condition.
One can always put a cold light head on most enlargers
but original heads may be hard to find so if you buy an
enlarger with an Arista head on it and don't also get the
original you are pretty much stuck if it turns out you don't
like the cold-light head.
BTW, despite some contrary claims in popular literature
there is no difference in tone rendition of a cold light
head from any other kind of diffusion source and, when paper
grade or negative contrast is adjusted, no difference
between diffusion and condenser heads. Dr. Richard Henry, in
his book _Controls in Black and White Photography_ (long out
of print) shows curves made using both adjusted paper grade
and adjusted negative contrast with both types of light
source. The curves lie exactly on top of one another.


--
---
Richard Knoppow
Los Angeles, CA, USA

In article ,
"Richard Knoppow" wrote:

I am not a particular fan of cold light heads. Several
years ago I bought one for my Omega D2v but went back to the
condenser head before long. I got good results from the cold
light head but it was no better than the condenser and,
after a careful alignment, no more uniform plus I prefer the
tungsten source when I am using VC paper (which is most of
the time). The cold light does give more light output for
4x5 negatives and is useful in printing very dense ones but
that is a rare condition.
One can always put a cold light head on most enlargers
but original heads may be hard to find so if you buy an
enlarger with an Arista head on it and don't also get the
original you are pretty much stuck if it turns out you don't
like the cold-light head.
BTW, despite some contrary claims in popular literature
there is no difference in tone rendition of a cold light
head from any other kind of diffusion source and, when paper
grade or negative contrast is adjusted, no difference
between diffusion and condenser heads. Dr. Richard Henry, in
his book _Controls in Black and White Photography_ (long out
of print) shows curves made using both adjusted paper grade
and adjusted negative contrast with both types of light
source. The curves lie exactly on top of one another.

I agree with all the above, and would add just a simple note for
discussion. One would have to selectively adjust contrast to match the
light sources - that is the same filtration won't produce the same
characteristic curves using the same negative. My personal belief and
you have stated a portion of it, that is: the cold light source was
first introduced as a light source for printing quite dense collodion
negatives that museums and archiving facilities had in quantity as a
quicker method for masking some lighter defects.

--
Reality is a picture perfected and never looking back.

"____" wrote in message
...
In article ,
"Richard Knoppow" wrote:

I am not a particular fan of cold light heads.
Several
years ago I bought one for my Omega D2v but went back to
the
condenser head before long. I got good results from the
cold
light head but it was no better than the condenser and,
after a careful alignment, no more uniform plus I prefer
the
tungsten source when I am using VC paper (which is most
of
the time). The cold light does give more light output for
4x5 negatives and is useful in printing very dense ones
but
that is a rare condition.
One can always put a cold light head on most
enlargers
but original heads may be hard to find so if you buy an
enlarger with an Arista head on it and don't also get the
original you are pretty much stuck if it turns out you
don't
like the cold-light head.
BTW, despite some contrary claims in popular
literature
there is no difference in tone rendition of a cold light
head from any other kind of diffusion source and, when
paper
grade or negative contrast is adjusted, no difference
between diffusion and condenser heads. Dr. Richard Henry,
in
his book _Controls in Black and White Photography_ (long
out
of print) shows curves made using both adjusted paper
grade
and adjusted negative contrast with both types of light
source. The curves lie exactly on top of one another.

I agree with all the above, and would add just a simple
note for
discussion. One would have to selectively adjust contrast
to match the
light sources - that is the same filtration won't produce
the same
characteristic curves using the same negative. My personal
belief and
you have stated a portion of it, that is: the cold light
source was
first introduced as a light source for printing quite
dense collodion
negatives that museums and archiving facilities had in
quantity as a
quicker method for masking some lighter defects.

--


I think you are thinking about mercury vapor lamps.
These were widely used for motion picture phtography in the
silent era. Some they were also used for plate burning for
half-tone plates and in some large format enlargers such as
the old Saltzman units. These lamps must be run continuously
and exposure controlled with a shutter. The output is mostly
near UV.

Cold light heads are fluorescent lamps. They are actually
similar to a low pressure mercury lamp inside but the inside
surface of the envelope is coated with a fluorescent
material which converts the UV to visible light. The mix of
materials in the coating determines the spectral output.
There are low equivelent color temperature cold-lights which
will work fairly well with variable contrast filters. I
believe the Ilford VC lamp is composed of two fluorescent
lamps, one concentrated in the green range. However, most of
the old cold-lights were very blue intended to be used with
graded paper.

While any diffusion head tends to blur certain kinds of
negative blemishes the increased paper contrast needed to
print with them sometimes brings them right out again. Even
with a cold light one must be careful of dust:-)

I don't know when cold light was introduced but I think
it may have been as early as the late 1930's. They
certainly became popular in the late 1940's.

--
---
Richard Knoppow
Los Angeles, CA, USA