Advantages of cold light heads

[BetterSense]

I now have an Aristo cold light head for my D2. I'm not sure what advantages this will have except maybe now I won't have to warm my negatives up to keep them from popping. I'm worried, however, that my old negatives will become less printable since the instructions say to develop negatives for 30% longer, and that seems like a lot. Has anyone switched from the condenser head to a cold-light head, and what differences did you see in your final prints? What compensations did you have to make? How did you change your development routine?

 

[ann]

I bounce back and worth from several types of light sources, and frankly it is not a big deal. I basically have been printing workflow standarzied, using grade 3 paper, and the times may change a bit from light souce but your negartives will print, you may change contrast grades but i really won't worry so much, just go make some test prints and see what your results look like and then make any necessary adjustments from that point.

 

[ic-racer]

Your older negatives may need to print on one paper grade higher.

Major advantages over the DV Omega consenser head:
1) Dust is less noticable in prints. It is easier to use the glass carrier.
2) No need to change condensers when changing lenses


Major disadvantages:
1) Light output not constant during exposure (there are a lot of clever ways to work around this like bulb pre-heat and compensating timers).

 

[BetterSense]

Major disadvantages:
1) Light output not constant during exposure (there are a lot of clever ways to work around this like bulb pre-heat and compensating timers).

The Aristo cold light head has a heater that keeps it at 100*F all the time, supposedly so that the bulb is pre-heated when you go to expose. Do you find that the output still varies overtime?

1) Dust is less noticable in prints. It is easier to use the glass carrier.

With the cold light head, I'm hoping that I can avoid using a glass carrier. I have been going to buy one because my negatives pop on long exposures, but I hope that with the cold light head there will be so little heat that i can just use a normal glassless carrier without problems.

 

[jp80874]

What size negatives?

John Powers

 

[pentaxuser]

This is a very "a propos" thread, given that I have been reading Fred Picker's 1974 ZoneVI Workshop. He is/was( is he still alive?) utterly sold on such cold cathode heads v condensers, listing no disadvantages whatsoever. I always get a little worried when someone describes something as virtually flawless in comparison with other types of enlarger heads.

Not an attempt to hijack the thread but strangely enough he makes no mention of the pros and cons of tungsten-halogen diffuser heads. For Fred it was a straight fight between condensors and cold cathode. Maybe tungsten-halogen diffuser heads didn't exist in 1974? At my age, 1974 seems like yesterday but of course a lot has happened in the intervening years

pentaxuser

 

[Ken Nadvornick]

...I have been reading Fred Picker's 1974 ZoneVI Workshop. He is/was( is he still alive?)

http://www.fredpicker.com

Ken

 

[RalphLambrecht]

This is a very "a propos" thread, given that I have been reading Fred Picker's 1974 ZoneVI Workshop. He is/was( is he still alive?) utterly sold on such cold cathode heads v condensers, listing no disadvantages whatsoever. I always get a little worried when someone describes something as virtually flawless in comparison with other types of enlarger heads.

Not an attempt to hijack the thread but strangely enough he makes no mention of the pros and cons of tungsten-halogen diffuser heads. For Fred it was a straight fight between condensors and cold cathode. Maybe tungsten-halogen diffuser heads didn't exist in 1974? At my age, 1974 seems like yesterday but of course a lot has happened in the intervening years

pentaxuser

Fred Picker is unfortunately not with us anymore. He was a great photographer, teacher and inventor, and he managed to bring several useful and reliable products to the market. I have the highest respect for him and his contribution to photography. Unfortunately, he wasn't always able to keep marketing and photographic advice entirely separated.

It has been proven many times that there is no tonal advantage of diffusion over condensor light sources. He insisted that there was and even convinced AA of it. The truth is, as long as the negative development is adjusted for the type of light source used, both produce identical images.

 

[pentaxuser]

Ralph and Ken, thanks for the replies. OK this isn't strictly relevant to the thread and sorry, OP, but the link to his website merely mentions his dying 8 years ago this month but doesn't mention cause of death nor age at death.

Can anyone supply that information? Thanks

pentaxuser

 

[Ronald Moravec]

Ralph is almost 100% correct. If the negative is developed for the light source, there are very small differences between the two. But they are so close, you need the two prints side by side to see it. You do not get the same results by using 2 & 3 paper with the same neg in different machines. I am talking taylored to light source negs.

I get more contras shadows shadows and less highlight separation with diffusion and slightly smaller grain and certainly not any significant "dust supression".

The biggest advantage is and burn in is easier with diffusion if a heavy burn is reguired.

Either one works and the skill of the printer is FAR more important than either having an advantantage over the other.

My darkroom has condenser and diffusion Leica Focomats, condenser and diffusion 4x5 Omegas, and condenser and diffusion Phillips tri color, and an Aristo cold light for the condenser Omega. I can work them all. Cold light is the SAME as diffusion if color is correct.

30% longer is way too much. 15 would be closer. There is a difference of one paper grade.

 

[Ken Nadvornick]

...sorry, OP, but the link to his website merely mentions his dying 8 years ago this month but doesn't mention cause of death nor age at death.

Can anyone supply that information? Thanks

I believe I read somewhere that it was kidney failure and an informed request by Mr. Picker to discontinue treatments. I do not know his age.

Disclaimer: The above info is from memory only. If it's important, you might wish to confirm it with someone who was closer to Mr. Picker. I think I've seen past APUG posts from a few who might qualify in that regard.

Ken

 

[fschifano]

Not an attempt to hijack the thread but strangely enough he makes no mention of the pros and cons of tungsten-halogen diffuser heads. For Fred it was a straight fight between condensors and cold cathode. Maybe tungsten-halogen diffuser heads didn't exist in 1974? At my age, 1974 seems like yesterday but of course a lot has happened in the intervening years

I don't think you're hijacking the thread at all. In fact, I think you bring up a valid point.

A little research (here) tells me that diffuse tungsten-halogen lamp houses were introduced by Omega as early as 1968. By '71 the still in production and essentially unchanged Super Chromega D was introduced.

Tungsten-halogen diffuser heads, while not commonly referred to as cold light heads, can be considered as such. I seem to remember these color heads from Omega being referred to as "cold lights" when they were newly introduced. They offer the same advantages over a condenser head that a cold cathode head does and more. There is no excessive heat build up at the negative stage. There is no need for lamp warmers, warm up time, compensating timers, and whatever other excess gadgetry is involved to keep the beast under control. All you need is a relatively simple power supply and voltage regulator to keep the tungsten-halogen lamp happy. Flip the switch and the lamp comes on at full power instantly. Flip it again, and it's off. The color temperature of the tungsten halogen lamp is perfectly matched to almost all variable contrast papers, and they are fast - sometimes too fast. Every VC paper I've tried under a tungsten halogen color head comes in at right around grade 2 with no filtration. So what does a cold cathode lamp buy you that a tungsten-halogen lamp doesn't? What am I missing here?

 

[jerry lebens]

In my experience, prints made with cold cathode/diffuser heads tend to have a little less sharpness than prints made with a condenser head.

This has the effect of smoothing out grain and is particularly noticeable in skies and other smoothly toned areas.

Regards
Jerry

 

[Anscojohn]

Regarding dust and scratch suppression. I worked as a production printer in the late 1960s, working with 6x6 negs in strips which the darkroom go-fer carred from printer to printer slung over his shoulder, a hundred at a time, like a sack of grain. Sometimes he dropped them; they even got ground into the floor. The scratches in the negs were almost palpable. When printed with cold-light heads on Omega D2s and Beseler 45s, the scratches never showed on the prints.

 

[BetterSense]

What size negatives?

All sizes, but 4x5 is most important to me.

 

[pentaxuser]

Frank You may have got to the answer. I have re-read the section and Fred refers to a cold light head not a cold cathode head which is like a fluorescent tube and is genuinely cold whereas a diffuser uses a hot source, namely the tingsten halogen bulb but has other means of preventing the heat reaching the negative. So maybe I was reading something into his use of cold light head wrongly and it was me who made 2+2 = 5.

Fred's coldlight head is listed in his catalogue at the end of the book and is called a Codelite CO-1. It seems to have two lights in the head although the lights can't be seen and are operated by separate rheostats to give an infinite mixture of hard and soft lights

Looking at the set-up I think this Codelite isn't a cold cathode system and it relies on a thick diffuser to prevent any heat gettingto the negs.

Anyone whose experience goes back to the 70s and who is familliar with Fred's equipment and/or has the book might be able to give the definitive view on what Fred's coldlight head was.

The way Fred describes it I think it was the forerunner of the Ilford Multigrade head which isn't cold cathode as far as I know. Just as an interesting aside it cost £658.20 which is quite expensive now but in 1974 must have been an absolute fortune. Maybe we are luck to be analogue users now rather than 35 years ago.

pentaxuser

 

[ic-racer]

The Aristo cold light head has a heater that keeps it at 100*F all the time, supposedly so that the bulb is pre-heated when you go to expose. Do you find that the output still varies overtime?

Yes, but it is not that bad and you can work around it if you know what is going on. Per the graph, at 60 seconds the falloff is only one-quarter of a stop.

This data is from the 1414 head (not 1212 as the graph states). The smaller Omega sized head may be a little different. Also, on mine the heater thermostat was set for around 40 deg C.

 

[ic-racer]

Maybe tungsten-halogen diffuser heads didn't exist in 1974?

pentaxuser

Tungsten subtractive printing was around ages before the additive two-tube cold cathode systems and continues to be the best way to expose multigrade silver materials.

 

[mike c]

ic-racer,not to good with graphs but as temp goes up intensity of the light(brightness) goes down? Why the heater then? I could be miss under standing your graph mybe but thought it was the other way round.
Mike

 

[mike c]

Ok ic-racer I was reading it wrong,actuality it is reverse what I was thinking(told you I was bad with graphs).
from 0 too -.25 is a increase of light intensity ?
Mike

 

[jerry lebens]

I can't comment on Aristo heads, but my ancient DeVere Cold Cathode - fitted on a DeVere 54, the precursor to the 504) - doesn't have a heater : You leave it switched on all the time and control exposure by swinging a safety filter into the light path.
Consequently, it's best to use longish exposures (25 secs plus) and to count down using a loud clock, in case the mind wanders... The output is very blue, so options for MG filtration are limited.

I brought this up in case anyone out there has an old DeVere CC head and has fitted a timer - which is strictly verboten. I understand that, not only is there a problem vis a vis warm up, but the circuit providing power to the CC head must have a double pole switch (ie a switch that cuts both live and neutral). I understand that, without a double pole switch, there can be a dangerous kick-back voltage which is capable of disrupting the mains input and even damaging sockets... Some practitioners got around this by fitting Rayco timers, which had DP switching, and 'compensated' for the warm up time by using long exposures.

Regards
Jerry

 

[Sparky]

I think the BIG advantage most practitioners like adams and picker have found with the cold light head (that nobody's really addressed yet) is that the bulk of the light is actinic (blue-end of the spectrum) and therefore a higher percentage goes into converting silver halide molecules into an excited state and less is wasted on the infra red and heat (i.e. the case with quartz and other incandescents). What's the point in generating a lot of extra electricity and heat that won't be used for anything except popping your negs...??

As for the 'sharpness myth'. Well- it's a misunderstanding. Cold light heads are only APPARENTLY less sharp than CONDENSER heads. A 'regular' (incandescent) diffusion enlarger will give you a similar result to cold light, contrast wise given the same apparent grade (i.e. on graded paper). I think the argument about cold lights seeming less sharp is fallacious if you take this into account.

 

[RalphLambrecht]

Yes, but it is not that bad and you can work around it if you know what is going on. Per the graph, at 60 seconds the falloff is only one-quarter of a stop...

You seem to have this under control, but I'm glad I don't have to worry about it with my color head. I enjoy the stable light output (controlled by a voltage stabilizer) and wouldn't want to put up with the variables of a cold light. It looks to me that the cure is worse than the problem.

 

[RalphLambrecht]

Sorry, but I can't follow your argument.

...Cold light heads are only APPARENTLY less sharp than CONDENSER heads...

True, but 'apparently less sharp' is 'less sharp' to the observer.

...A 'regular' (incandescent) diffusion enlarger will give you a similar result to cold light...

True again, because they are both diffusion heads, but they are both 'apparently less sharp' than condenser heads.

...I think the argument about cold lights seeming less sharp is fallacious if you take this into account.

Not if you compare cold light to condensers.


If you compare cold lights to other diffusers, such as a color enlarger, they offer little benefit (less heat) but have some major disadvantages (unstable light output, warm up time required) and usually cost more, at least if you figure in the electronics to compensate for some of the problems.

I find color heads simpler to use with less things to worry about. Cold lights produce excellent results, but there is an easier way to get there.

 

[David A. Goldfarb]

The biggest attractions of cold light for me are dust suppression and the smoother look of cold light, though it means slightly less sharpness than other contrastier light sources. I try to compensate for that by maximizing sharpness in other ways (checking alignment, apo lenses, glass neg carrier) and developing for slightly higher contrast.

A cold light head without a heater unit or a compensating timer can be frustrating, particularly if you have short exposure times. In that case, it is often better to keep the head on and use a black card over the lens to time the exposure. A heater is a significant improvement and is good enough for moderate and longer exposure times. A compensating timer like a Metrolux, though, gives you much more precision, so you can use very short exposure times very reliably, if you need to make many identical prints of the same image.