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Thread: Cold lite?

  1. #21
    johnnywalker's Avatar
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    My Durst 1000 came with a condenser head and a Taucoli cold light head. I replaced the condenser head with the cold light head because my ceiling was occasionally too low with the condenser. I think I will put the condenser back on again, for a few reasons: first, my darkroom automation meter is pretty much useless with the Taucoli. The light appears greenish and dim, but in fact much less time is required than either the meter or I would think. Second, it takes a while to warm up, and third Durst suggests the use of a voltage stabilizer (which I have ignored). Finally, I'm finding it difficult to replicate the readings I get on the enlarging meter even after a short time (I'm trying to calibrate the meter to an enlarging time). This probably has something to do with the warm-up time. In short, it's getting to be more of a PITA than it's worth.
    If I had been present at the creation, I would have given some useful hints for the better arrangement of the Universe.
    Alfonso the Wise, 1221-1284

  2. #22
    RalphLambrecht's Avatar
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    Well, that's exactly how I felt when I tried them, and that's why I was asking. Of course, switching between the two light sources is not that easy, because they both need their own negative contrast. This explains why people who have contrasty negatives, and don't get good results with a condensor, have an easier time printing when they switch to the cold light head (or a diffuser). Of course, just developing softer negatives would have done the trick too.
    Regards

    Ralph W. Lambrecht
    www.darkroomagic.comrorrlambrec@ymail.com[/URL]
    www.waybeyondmonochrome.com

  3. #23
    Ian Grant's Avatar
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    In this day and age the only real advantage of a Cold light source is they are more compact than a colour head, require less stabilising, run cooler and are more economical both in terms of energy used and cost of lamps. I only needed 1 replacement in 30 years and the enlarger head was used professionally on a daily basis for well over half that timespan.

    In their heyday in the 50's & 60's they were reasonably priced while colour heads were still in their infancy, some using condensers and very expensive.

    I used a 5x4 enlarger with a De Vere Cold cathode head alongside a medium format Durst with a colour head and it was no more difficult to use, other than letting it warm up, there were certainly no idiosyncrasies.

    Having used condenser and colour head enlargers as well as the Cold cathode for MF & LF work I can echo others saying that a diffuser enlarger whether colour head or cold light is much nicer and easier to print with than a condenser enlarger, and that's based on printing customers negatives which weren't optimised in any way.

    Adam's big enlarger was a diffuser enlarger (not cold light), he explains how he made the light source in one of his videos.

    There was a British 5x4 enlarger made by Line & Jones until the late 1990's and they kept the price down by utilising a Cold cathode head, manufacturing costs are very much lower than condenser or colour heads.

    Having said that there may well be variations between makes of Cold cathode heads.

    Ian
    Last edited by Ian Grant; 02-16-2011 at 01:08 PM. Click to view previous post history.

  4. #24
    johnnywalker's Avatar
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    I replaced the cold light head on my L1000 with the condenser head today, and as a result I've decided not to let the dogs chew the Darkroom Automation enlarging meter after all. It works as it is supposed to with the condenser head, and although the first print is not "perfect", it gets me very close. I will miss the compactness of the cold light head, but se la guerre. It was getting pretty frustrating, to the point where my wife was complaining she had to cover the dogs' ears when I was in the darkroom. I don't know when, if ever, I would have figured it out without this thread.
    If I had been present at the creation, I would have given some useful hints for the better arrangement of the Universe.
    Alfonso the Wise, 1221-1284

  5. #25
    Adrian Twiss's Avatar
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    I have been internally debating the idea of getting a condenser enlarger to supplement my Durst Laborator which has a VC diffuser head. After reading this it looks like my time would be better spent fine tuning my negatives to print with a diffusion light source.

  6. #26
    johnnywalker's Avatar
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    Quote Originally Posted by Adrian Twiss View Post
    I have been internally debating the idea of getting a condenser enlarger to supplement my Durst Laborator which has a VC diffuser head. After reading this it looks like my time would be better spent fine tuning my negatives to print with a diffusion light source.
    From reading this thread I gather that a cold light head and a diffusion head are not exactly the same thing, and diffusion lights may not have the same issues my cold light head did. Not sure though.
    If I had been present at the creation, I would have given some useful hints for the better arrangement of the Universe.
    Alfonso the Wise, 1221-1284

  7. #27
    Ken Nadvornick's Avatar
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    Well, I realize that everyone's personal experiences are valid for them. But for the life of me I've just never seen all of these reported problems with fluorescent tube heads. My experience has always been one of reliable, rock-steady output with zero hand-holding on my part. But then that's the essence of closed-loop systems. They are by design intended to remove the need for hand-holding.

    A typical darkroom session begins* by turning on an ancient Zone VI single-tube head (with an upgraded V54 lamp) and an equally ancient Zone VI Compensating Enlarging Timer. The head came with a photocell already installed. It mates to the timer. There is an internal heater that, in 20 minutes, has done its job. That frees me to set out chemistry, mount a negative, compose, focus, yadda, yadda.

    From that point forward I never, ever have to think about the light source again - period. The photocell watches. The timer compensates. The seconds are adjusted on the fly. And the light is ungodly steady in its delivered volume. Changes in lamp tube temperature have no effect. Changes in focusing time, exposure time, down time... all of it, means nothing. All sources of drift are effectively factored out without any effort - or even thought - on my part.

    When paired with a similar Zone VI Compensating Developing timer for my developing tray I can, as I said earlier, make identical prints, on the first try, a week apart. That's not hyperbole. I've done it. In fact, I once did it with step wedge prints while testing contrast filters. And if ever there would be a procedure that would show even a slight drift in the light source, that would be it.

    To be perfectly honest, I'm so damned spoiled by the fact that I can completely factor out my cold light head as a variable that it would be like starting all over again if I had to worry about it at any level. Heck, if I ever have to go back to light bulbs and condensers you can be darned sure that the first thing I'll do is install a photocell into the bulb housing. Those guys are subject to drift as well, and color changes with it.

    I've just never seen all the fiddling everyone says in endemic to these sources. But then my water temperature is also rock-steady (Hass Intellifaucet K250), and my magnetically-stirred hotplate solutions are - or can be, if I need them to be - rock-steady (Corning PC-420D with feedback temperature probe).

    These are not Rube Goldberg solutions. Not a shred of chewing gum or duct tape to be found. Instead, they are elegantly designed and implemented solutions by people who knew what they were doing. They are fire-and-forget solutions. You simply turn 'em on and walk away with one less variable to worry about. Every single time...

    Ken

    * Or began, since I'm now still wrestling with rehabbing that used Aristo VC head that is about to get new tubes.
    "They are the proof that something was there and no longer is. Like a stain. And the stillness of them is boggling. You can turn away but when you come back they’ll still be there looking at you."

    — Diane Arbus, March 15, 1971, in response to a request for a brief statement about photographs

  8. #28
    Ian Grant's Avatar
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    Quote Originally Posted by johnnywalker View Post
    From reading this thread I gather that a cold light head and a diffusion head are not exactly the same thing, and diffusion lights may not have the same issues my cold light head did. Not sure though.
    A cold cathode/cold light head uses a fluorescent tube, expensive because they are handmade but they have a long working life and generate very little heat, there's then a diffuser between it and the negative.

    A VC diffuser head or colour head uses a Tungsten halide bulb or set of bulbs and a light mixing box to scramble the light, this also uses a diffuser at the bottom of the box just above the negative.

    So in terms of output both give near identical scattering of light, a disadvantage of heads with Tungsten Halide lamps is extreme heat particularly if there's more than 1 lamp, a De Vere 5108 uses 4 500watt bulbs so needs two cooling fans, the lamps have a short life and are expensive.

    The big advantage of a Colour/VC diffuser head is that dichroic filters can be placed between lamp & mixing box to control colour balance or VC filtration.

    Ian

  9. #29
    RalphLambrecht's Avatar
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    Quote Originally Posted by johnnywalker View Post
    From reading this thread I gather that a cold light head and a diffusion head are not exactly the same thing, and diffusion lights may not have the same issues my cold light head did. Not sure though.
    There are two types of density: specular and diffuse. The ratio of the two is called the Callier coefficient. No existing light source is truly specular or truly diffuse, but point-light sources are very close to being perfectly specular, and cold-light and diffusion heads are very close to being perfectly diffuse. A condenser head is somewhere in between. In other words, as far as the enlarging 'quality' of light sources goes, cold-light and diffusion heads are the same.
    Regards

    Ralph W. Lambrecht
    www.darkroomagic.comrorrlambrec@ymail.com[/URL]
    www.waybeyondmonochrome.com

  10. #30
    johnnywalker's Avatar
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    The glass on my cold light head is a cyan colour. You can barely see the image on the paper when the filter is in place, the safe-lights on, and the lens at a middle f-stop. This makes focusing difficult (even wide open, and impossible if the red filter is in place) and it fools the enlarging meter as well as me. On the other hand, the paper is exposed very quickly (faster than the equivilent f-stop on the condenser head). Is this typical, or unique to the Taucoli head I have?
    If I had been present at the creation, I would have given some useful hints for the better arrangement of the Universe.
    Alfonso the Wise, 1221-1284

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