cold light head

Discussion in 'Enlarging' started by frank, Jun 13, 2003.

  1. frank

    frank Subscriber

    Messages:
    2,094
    Joined:
    Dec 6, 2002
    Location:
    Bit north of
    Shooter:
    Multi Format
    So I finally got my LF enlarger, and I have a few friends telling me that I've just got to start printing on FB paper and get a cold light head for it to make really good prints. The trouble is, I can't see any magic in their cold light FB prints that I don't have in my condenser or diffusion head RC prints.
    I'm really looking forward to this new printing initiative where the same negative is printed by many different photogs from APUG to see different interpretations. Maybe then I will see a difference.
    Until then, what can anyone tell me about cold light heads? I know just a bit: there is an older version that requires an expensive controller, and there is a version meant for VC paper with blue and green tubes in it. I've also read that negatives meant to be printed with a cold light source should be denser than normal.
    (Isn't photography great, there's no end to this learning.)
    Frank
     
  2. lee

    lee Member

    Messages:
    2,913
    Joined:
    Nov 23, 2002
    Location:
    Fort Worth T
    Shooter:
    8x10 Format
     
  3. Les McLean

    Les McLean Subscriber

    Messages:
    1,609
    Joined:
    Oct 18, 2002
    Location:
    Northern Eng
    Shooter:
    Multi Format
    Cold light heads are usually not so bright as condensor or diffuse light sources therefore exposure times are longer. The same negative printed on cold light will be about 1 paper grade softer than if printed on condensor. IMO the bit about the density of the negative is total rubbish. Small blemishes such as dust etc on negatives will be less noticeable when the neg is printed on cold light, it's something to do with the difference in the way the light is scattered by a condensor. Another myth IMO, is that you can use a regular cold light to print using VC paper and compensate for the fact that the colour of the light is blue by introducing extra yellow filtration. To print VC you need the green and blue light source like the Zone VI that I use although I understand that Aristo do make a VC light source that is very good but not like the Zone VI.
     
  4. lee

    lee Member

    Messages:
    2,913
    Joined:
    Nov 23, 2002
    Location:
    Fort Worth T
    Shooter:
    8x10 Format
    Les and everyone else if they are not asleep by now,

    Aristo makes the VCL 4500 with the green and blue lights. I agree that this is best way to attack the VC problem. I neglected to mention the Zone VI head because, as an old fart, I forgot. I have printed with the Zone VI and the Aristo heads and both do a very good job. The Zone VI does cover up to 5x7 and that is a very good reason to own one if you shoot 5x7. Be advised that both systems are painfully expensive.

    In zone system language, one would process the film to a density of 1.2 >fb+f with a condenser head and to a density of 1.3 >fb+f at zone VIII. This will account for the one grade softer print with the cold light. The way I see it the bit about density of the negative is not really total rubbish to use your words. :smile: If you have a cold light with the old style tube, Aristo will sell you a newer tube (light source) that will be closer to the VC Paper response. It has more yellow in it. This is the V54 light I mentioned in the post above. There were several versions of the cold light tube but the most common (I think?) of the old styles is the V45. That was the one that everyone attempted to use with the 40 yellow cc filters. It is the one that should be replaced unless you can find graded papers you like and plan to use.

    http:\\aristogrid.com

    lee\c
     
  5. Donald Miller

    Donald Miller Member

    Messages:
    6,242
    Joined:
    Dec 21, 2002
    Shooter:
    Large Format
    I have printed with cold light or dichroic heads for almost twenty years. I always accepted as "gospel" the Ansel Adams "text" on the Callier effect. I recently came upon a study of the quality of light as it relates to enlarging. I have recently been led to believe that the condensor or point light sources will provide the greater degree of print sharpness if all other pararmeters in a comparison are kept intact. In other words if we compare "apples with apples". --No oranges allowed!

    I had never considered the dust that the diffusion light sources were compensating for were also having a similar effect on negative detail. It seems that they do, though.

    Am I about to run out and buy the latest Durst with the Azo head? Nope, don't think so.
     
  6. Loose Gravel

    Loose Gravel Member

    Messages:
    921
    Joined:
    Feb 28, 2003
    Location:
    Santa Barbar
    I have printed with the W55, W45, the VC8100, and now the V54. The V54 is the winner here. It is, by far, the brightest of all of these. Printing 5x7 onto 8x10 paper with exposures in the f/22 - 32 at about 10sec on Bergger VC CB. This is at least 3 stops faster than the VC head. It is kind of nice to just turn the knob for a contrast change, but exposures are long, hard to see, and the unit is very expensive.

    The W45 doesn't offer a very good distribution of contrast, even with the yellow filter and although fairly bright, still not as bright as the V54.

    The final straw here is that all coldlights require some kind of closed loop timer or stabilizer. The 'thermo' or heater in the head helps, but is not good enough to provide consistant exposures. Light output of the coldlight tubes is dependent partially on tube temperature. In fact, it is possible in some cases to have part of the tube getting brighter, as another part of the tube gets dimmer.

    Given this and other variables, the dual grid VC heads cannot be controlled as well as the single (V54) heads, because the dual grids have two lamps on at the same time. If they are used in the split printing mode, then a controller will work, but not otherwise.

    If you are going for a coldlight, get the V54. With a controller, I use a Metrolux 2, exposures are consistant to better than 1%, with or without the thermo even on.
     
  7. lee

    lee Member

    Messages:
    2,913
    Joined:
    Nov 23, 2002
    Location:
    Fort Worth T
    Shooter:
    8x10 Format
    I have a Metrolux II with the closed loop system. You are right that the VCL 4500 is slow.

    lee\c
     
  8. blansky

    blansky Subscriber

    Messages:
    5,702
    Joined:
    Nov 6, 2002
    Location:
    Wine country
    Frank:

    I think your friends were partly right. I think you'll find the switch to fiber based paper will be a positive one. I suggest using glossy, and experiment with some warm tone and then selenuim and sepia toning. There are lots of great papers besides Bergger but Bergger is definately one to try. I think once you work with fiber papers you will be hooked, even though they are slightly more work.( washing, mounting etc.)

    As for the enlarger, I have both cold light head and a color head.I use both and they have different characteristics that have many people choosing sides about. Obviously you can make incredible prints with all kinds of enlargers. I have a Zone VI VC and a Beseler.

    One thing not mentioned on the cold head is that you don't seem to have to deal with negative pop which because of the heat on the other types can make the neg "pop" itself out of focus. On the downside they are a little trickier to focus.

    The other controversy you will find is timers. I use a Metrolux II timer which doesn't cound down seconds but counts lux units. It has a sensor in the light head that measures the light output and compensates for fluxuations caused by the bulb and also your electrical circuits. ( I have a heater and a vacuum easel that normally would dim the lights and cause fluxuations in the exposure).

    Other people swear by other styles and methods of timing your exposures.

    My advice -use what you have and can now afford and study other methods while you are learning. But do switch to fiber paper.

    Just an opinion


    Michael McBlane
     
  9. Ed Sukach

    Ed Sukach Member

    Messages:
    4,519
    Joined:
    Nov 27, 2002
    Location:
    Ipswich, Mas
    Shooter:
    Medium Format
    APUG is the *last* place I'd ever expect to see a "war". This place is wonderfully tolerant of differing opinions. Someone just asked me why I was on here.. my answer was, "I can even be *wrong* without having my fingers broken.

    I've developed a preference for one particular paper: Ilford MG Portfolio -- which is "RC" paper. Again, the late and *sorely missed* Camera and Darkroom had an extensive article about the construction and longevity of "Resin Coated" - as compared to "Fiber Based" papers. Two significant differences were that FB has an emulsion applied to a "Baryta" (a form of white clay) support, and, with RC, the emulsion is applied to Titanum Oxide (typical white pigment in oils); and, of course, the polyethelene encapsulation of the (usually) paper fiber base. The emulsions themselves were the same.

    C&D concluded that there was *no* significant difference in longevity between the two.

    Ilford "Portfolio" is in demand here in this area - I've managed to stockpile four or five packages of 16" x 20" (ordered and waited for).

    This is the first time I've heard of a gallery - of any sort - refusing RC prints.
     
  10. frank

    frank Subscriber

    Messages:
    2,094
    Joined:
    Dec 6, 2002
    Location:
    Bit north of
    Shooter:
    Multi Format
    I've reposted this question in the B+W paper and chemistry forum where it is more appropriate.


    Please forgive my ignorance, but what is the relative expected lifetime of black and white RC, FB, colour papers (there are diferent types) and digital prints (again there are different types)?
    I have B+W prints made on RC paper back when I was at university (almost 30 years ago) that still look good, and have spent much of their lifetime displayed on walls, though not in direct sunlight.

    Frank
     
  11. chrisl

    chrisl Member

    Messages:
    178
    Joined:
    Jan 30, 2003
    Location:
    Berkeley, Ca
    I'd heard there's very little/No difference in a coldlight vs. diffusion head as light sources. I moved to a diffusion head from condensor and the dust factors apparant to me easily. Sharpness? I'm not that observant. They both give sharp prints to me if the negative's sharp lol But anyway, seems there's a bit of controversy over this light source issue.

    Chris
     
  12. Loose Gravel

    Loose Gravel Member

    Messages:
    921
    Joined:
    Feb 28, 2003
    Location:
    Santa Barbar
    Chris

    I think you are right. Years ago I put a diffusion surface (white plexiglass) in my condenser head and could not tell it from my coldlight. Diffusion means you are scattering the light to the maximum degree --- that light strikes the negative from ALL angles. Condensed light strikes the negative at one angle --- orthogonal to the surface. In truth, coldlights, condensers, diffusers, point lights are all in the middle to varying degrees. The above relates only to the optical properties.

    The nice thing about a coldlight is that it is very diffuse and at the same time small, efficient, and generates little heat, which can be a real problem. If you have a good diffusion head or color head, you don't need a coldlight if you are not having heat or space problems.
     
  13. frank

    frank Subscriber

    Messages:
    2,094
    Joined:
    Dec 6, 2002
    Location:
    Bit north of
    Shooter:
    Multi Format
    Thanks for the responses. I think I'll just stick with the diffusion head and not worry about a cold light head unless one drops into my lap for a song.

    As for my friends, I think I'll stick with them too.

    I reposted my FB/RC question in the B+W paper and chemistry forum.



    Frank
     
  14. bmac

    bmac Member

    Messages:
    2,156
    Joined:
    Sep 30, 2002
    Location:
    San Jose, CA

    Didn't you have problems with heat buildup with this setup?

    Brian
     
  15. Loose Gravel

    Loose Gravel Member

    Messages:
    921
    Joined:
    Feb 28, 2003
    Location:
    Santa Barbar
    Brian,

    I only did it as an experiment to see if diffusion was the same as a coldlight. There were so many myths about coldlights in the early 80s that I had to try a diffusion plate to compare. It was not any hotter than the condenser, but it was very dark. I don't recommend it and prefer coldlights as long as I have closed loop system of some kind.
     
  16. bill schwab

    bill schwab Advertiser

    Messages:
    3,751
    Joined:
    Jun 16, 2003
    Location:
    Meeshagin
    Shooter:
    Multi Format
    As one who also followed the teachings of Ansel and Fred Picker, I printed for years with Cold Light. I do have to admit though that I have returned to the condensor for the past 10 years and don't think I'll be going back the cold light way. It is a personal choice based upon the results I desire and I find that cold light tends to be too flat for my tastes. Also too soft. Imagine what happens when using noise reduction or dust and scratch removal filters in Photoshop... your image quality becomes softer due to pixel "dot gain". This same effect happens with cold light. My images tend to be very soft in quality and cold light just pushes them too far over the edge for me.
     
  17. steve

    steve Member

    Messages:
    243
    Joined:
    Sep 12, 2002
    A cold light head is a diffusion light source. Placing a piece of flashed opal glass or other diffusion material between the condensers and the negative turns a condener enlarger into a diffusion enlarger. A colorhead is also a diffusion light source.

    I have used:

    A Beseler 45 enlarger with a condenser head for black and white and color. Color using CC filters in the filter compartment.

    A Beseler 23C with a conderser head for black and white work.

    An Omega D5 with a dichroic color head for color and black and white.


    I have owned a D2V since 1973 and have used it as:

    1. A condenser enlarger for B&W work using Polycontrast filters below the lens, and Polycontrast sheet filters in the filter drawer.

    2. A diffusion enlarger for B&W using flashed opal glass under the condenser stack using Polycontrast sheet filters in the filter drawer.

    3. A diffusion enlarger using an Aristo cold light head and graded paper.

    4. A color and B&W enlarger using a Beseler Minolta 45A colorhead diffusion light source.

    Why use a diffusion source? If you use a diffusion enlarger, you will find that you need to use a higher contrast paper (usually 1 to 1-1/2 grades higher) for negatives shot to be printed on a condenser enlarger.

    This "effect" can be used when shooting negatives for a diffusion enlarger. You can make longer scale negatives if you are using a diffusion light source for printing. In my experience about 1-1/2 stops. This means you can expose the film for greater shadow detail while still retaining detail in the highlights without resorting to as much dodging and burning - or under development.

    With a low contrast subject, you can develop longer or use a higher contrast developer than making the same negative for use in a condenser enlarger. Again, making a longer scale negative - or one with greater tonal scale separation.

    Dust will still show up with a diffusion light source. Some scratches will be minimized, but not eliminated. As noted in a previous post, a cold light source may help with heat and negative "popping" on long exposures when compared to a condenser enlarger.

    Sharpness = edge definition with enlargers. In ranking sharpness, enlarger types are:

    1. A point source enlarger will give the highest edge definition and apparent "sharpness."

    2. A condenser is second in edge definition.

    3. A diffusion enlarger is last in edge definition and making a print look "sharp."

    I use a diffusion sources for black and white work because I find it easier to print longer scale negatives with the diffusion light source. I don't mind the tradeoff of edge definition - some people don't like the "softer" look. I think the total final look is "smoother" in both tonality and contrast with a diffusion source.

    Choose the light source that you are most comfortable working with, and that enhances the look of your work. Don't choose it by what other photographers use (i.e. Ansel used a diffusion enlarger) - it's YOUR work.