Zone VI cold light head

"Richard Knoppow" <dickburk.DeleteThis@ix.netcom.com> wrote in message
news:13ot3202q0b6nff@corp.supernews.com...
>
> "G.T." <getnews1.DeleteThis@dslextreme.com> wrote in message
> news:13osjvel92cbncd@corp.supernews.com...
>> 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
 >> Stay informed about: Zone VI cold light head 

"G.T." <getnews1 RemoveThis @dslextreme.com> wrote in message
news:13ot5g3qc9790cc@corp.supernews.com...
>
> "Richard Knoppow" <dickburk RemoveThis @ix.netcom.com> wrote in
> message news:13ot3202q0b6nff@corp.supernews.com...
>>
>> "G.T." <getnews1 RemoveThis @dslextreme.com> wrote in message
>> news:13osjvel92cbncd@corp.supernews.com...
>>> 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
dickburk RemoveThis @ix.netcom.com
 >> Stay informed about: Zone VI cold light head 

In article <13ovklqo1vdj83c.RemoveThis@corp.supernews.com>,
"Richard Knoppow" <dickburk.RemoveThis@ix.netcom.com> 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.
 >> Stay informed about: Zone VI cold light head 

"____" <internetphobic.DeleteThis@deletedmail.com> wrote in message
news:internetphobic-23CDFA.18424617012008@newsgroups.comcast.net...
> In article <13ovklqo1vdj83c.DeleteThis@corp.supernews.com>,
> "Richard Knoppow" <dickburk.DeleteThis@ix.netcom.com> 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
dickburk.DeleteThis@ix.netcom.com
 >> Stay informed about: Zone VI cold light head