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Discussion in 'Darkroom Equipment' started by ronlamarsh, Feb 10, 2011.
I have a V54 aristo cold lite, how can you tell when the bulb needs replacement?
Louise Kessler from Voltarc/LCD (Aristo) has given the following guidelines in post #23 from this thread:
"...the nanometer output of the given lamp will change over time. The more the lamp is used, the more it will age and the phosphor will degrade. The strongest output of any lamps will be in the 1st hundred hours of its use. After this time it goes into its "median age" - think of a bell curve and it will slowly go down in strength. Replacement of the lamps on the down side of the curve is dependent of the photographer and how much he’s willing to lengthen his timing to compensate for the lamps aging.
"Usually at the end of a lamp’s life the nanometer output and its ability to make the chemical reaction is very low. The lamp has a harder time to recover from exposure to exposure. The lamp is basically telling you that it’s done and will shortly - electrically die."
She was originally discussing the Aristo VCL variable-contrast dual-tube lamps but her above comments, as she states, should apply to any of the Aristo lamps.
When you turn it on and it no longer lights up
Why anybody puts up with the idiosyncrasies of this type of lighting is beyond me.
What do you use Ralph? I don't have your books.
That's my point. It doesn't matter. Diffusion, condensor or whatever enlarger, all one has to do is process the negatives accordingly. There is no inherent quality difference with one or another type of light source. If that's agreed (the evidence is proven by contemporary literature), the optimum light source is one that is consistent and flexible in changing contrast. This typically leads to diffusion color heads or condensor enlargers with under-the-lens filtration. Considering the above, I don't see why cold-light heads are so popular in the US. They offer no quality advantage over other light sources, but have a few disadvantages in the areas of consistency, repeatability and convenience that would drive me nuts.
Perhaps that is why I've had a hard time deciding which head I like best on my enlarger. I use an old Omega D2 that came with a condenser head and I later picked up an Omegalite head that uses a circular fluorescent bulb. I tend to use that head most because I feel it might be better for various film formats since my enlarger does not have the variable condensers. I experimented with different fluorescent bulbs and found one that seems to work well with my negatives. I've stayed with that setup for years now.
You matched your light source with your typical negative contrast, which is just fine. Others may have to change film processing to adjust their negative contrast to match their light sources, and that's reasonable too. However, running out to spend a ton of money to change a light source in hopes of fixing the underlying problem of inappropriate negative contrast, is not advisable. This is especially true for cold-light heads, because I believe, they fix one problem and replace it with a few others.
Thank you. That's just what I learned first hand When I picked up a Beseler 45 With an Aristo lamp. I was thinking about replacing the tube with something more compatible with VC papers. Not worth the expense considering all the other crap you need to deal with. Sold the Aristo unit and got a condenser lamp house for the enlarger. Works like a charm, but I still prefer the dichro head on my Omega D4.
Everyone has their own experiences and preferences. I've used both the OEM condensers and third-party fluorescent cold lights in my Omega D5XL. Each has certain advantages and disadvantages over the other.
The sum of my own experiences led me to prefer the cold lights for black-and-white work. When the equipment is working properly, I find the cold light heads to produce consistent, repeatable output which I find very convenient to work with.
I can work out the formula for a print using fresh chemistry, make one, then shut everything down and leave it all for a week. When I return I can set out new fresh chemistry from the same stock, then precisely repeat the formula and obtain an exact duplicate of the original print on the first try. I've done this before, more than once. Can't get more consistent or repeatable than that.
The key, of course, is not the light source. All of these are prone to drift for various reasons. The key is using closed-loop control systems to manage that drift. I utilize several in my darkroom. Together these serve to remove a sizeable amount of the unexplained background "voodoo" that used to drive me nuts. ("What happened? I know I did everything exactly the same! Why is this different?")
But like most things in life, there are usually several ways to skin a cat. Cold light versus non-cold light is no different. Youz pays yer money, and youz takes yer chances...
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.
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.
Ilford sells them:
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.
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.
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.
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.
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.
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.