I'm not trying to talk anybody out of cold lights, but I would like to understand the advantages worth the disadvantages.
1) Dust is not much of an issue.
2) If you print for 14 hours and drink 9 beers and accidentally leave the enlarger in "focus", you will not fry your negative or light your house on fire.
3) There are dual rheostats built in for intensity and dry-down compensation. I guess these would be easy enough to build into a condenser enlarger. If you are looking for another hobby.
1) The lamp takes about 1/2 hour to warm up in the winter to become stabilized. But it takes about 45 minutes to set everything else up anyways.
As far as what is written about the separation of highlight detail and all that, I don't know. I like the prints I get from mine.
You state valuable advantages, but can't you get these from any diffusion enlarger without the electronic effort to keep the lamp at a stable output?
By the way, there is another potential disadvantage, you didn't mention. The cold light bulb is very close to the negative plane. I remember John Sexton showing me how this caused the pattern of the cold light bulb to show up on the paper when using very hard grades of paper. Have you ever noticed that?
Having used a De Vere cold cathode head for years from 1976 until 2006 without problems, I never found any disadvantages, I used to let it warm up for about 10 minutes which helped get consistent results. Mine gave very even light and the diffuser was more than enough to prevent the pattern of the lamp ever showing up.
However like Ralph I'd actually recommend a colour or Multigrade head for an advantage that's been missed. With a cold light source you need to use below the lens MG/VC filters, with a colour/MG head you just dial in the filtration.
A more obvious advantage is you can also colour print as well with a Colour head
I have not seen the bulb pattern on the paper, at any grade. That would certainly be a deal breaker, wouldn't it.
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Sorry, forgot to add: you don't have to use the VC filters below the lens with a cold light. Just put the filter on top of the negative holder. My filters are scratched and dusty, but with a diffuse light source, that 2mm or so the filter is above the neg (in addition to being a little out of focus) is more than enough. It's not an issue.
That only works if you have large filters I never saw filters large enough on sale in the UK to fit above a 5x4 negative.
Originally Posted by Rich Ullsmith
Ilford sells them:
Originally Posted by Ian Grant
I use the 12x12's on my Elwood.
Well, one more opinion. I switched to my first Aristo cold light in the early eighties, after hearing about the real reason Ansel, Fred Picker, and others, recommended it over condenser arrangements, due to the "Callier Effect (no relation. . .)", for which good explanations can be found on line, etc. The basic idea is that low density areas expose the paper much the same, but with highlights, more (stronger) light reaches the paper. This is not a simple contrast difference, as I understand it. Since the highlights do not suffer from the Callier effect using a cold light, greater range can be processed into the neg (more information and better separation), and/or a higher grade of paper used, which enhances the low end separation. I have made no direct comparisons, except that the very first neg I ever printed with the Aristo head was far more easier to print because of some bright sunlight falling on an interior wall. I used the same grade of paper as with the condenser head, but the burning in was strikingly easier, with no loss in mid range or low end separation.
The lack of negative buckle and dust issues are a bonus, and the light is very even corner to corner.
I replaced my original head about 10 years ago (when the first bulb tanked after 25 years) with the CL45, which has a filter drawer above the neg, using standard 6" filters (Ilford) with just a very thin trimming. I bought two "drawers" when I could, so switching between grades for split printing is very easy. I use the V54 lamp.
I have read arguments over the years on the verity of the Callier issue, so, it seems we all must decide for ourselves. I don't find the bulb troublesome at all, except for it's current availability. I am making the best prints I ever have with Ilford MGVI and this head.
I'm sure you are making great prints with it, but rest assured, the credit is all yours. Print quality does not depend on the type of light source. Fred Picker was a great photographer and salesman. Unfortunately, he oversold this item and, even more unfortunate, talked AA into spreading the myth. This is probably the only questionable statement in any of the AA books. Not too surprisingly, because AA did not use a cold light head himself, otherwise, I'm sure he would have noticed.
Comparing light sources has been done in several papers and books. I show one comparison in our recent book 'Way beyond Monochrome'. I have tested this to death! The conclusion was always the same: As long as the negative contrast is adjusted to the light source, identical prints can be made with any light source. Highlight wash-out or dead shadows are not a metter of the wrong light source, they are a matter of the wrong negative contrast and can be corrected that way.
Don't get me wrong. Cold light is not a bad light source. It's a good light source, but it doesn't have the superior qualities Fred Picker advertised with.
I just wondered what other benefits it may have and people like to put up with some of its idiosyncrasies.