Here is some research I Googled on the Callier Effect and enlargers. As I said, I personally use a Cold Light head. Some like the condensers, great. I control contrast through exposure and development and tailor it to my enlarger.
BTW, here is what Allan Ross uses to print the AA Special Edition prints;
"The prints are made by projection rather than by contact, regardless of negative format. This ensures a consistency in finished size and also affords the greatest control of dodging and burning. Most of the negatives in the series are 8x10 format, but other negative sizes include 5x7, 4x5, 31/4x41/4, and 120 rollfilm. The 8x10 and 5x7 negatives are printed in the Beseler 8x10 enlarger designed by Ross, with a custom Aristo 12"x12" cold-light head. Negatives 4x5 and smaller are printed with an Omega D5500 enlarger with a diffusion color-head."
Q: What is the Callier effect?
A condensor enlarger collimates light, which makes the light rays parallel. When these parallel light beams hit the negative, the light beams get scattered as they hit the emulsion. On low density areas (dark areas), the light passes through relatively unscattered. But in the high density areas (highlights), the light rays will scatter more. Where they scatter less, they are more intense on the paper, and where they scatter more they will be less intense on the paper. The more light passing through the negative onto the paper the darker the image on the paper. What this means is that those areas which are to be dark, will be emphasized as dark, and those areas that are to be light will be emphasized as light, in other words it tends to increase the contrast range of the negative. Ansel Adams says in The Negative that in his experience more negatives have too much contrast than too little. You can, and will, adjust your development of the negative if you read "The Negative" and understand the zone system. Even if you don't practice the zone system, you should make tests with your equipment (camera, enlarger, water, thermometers, chemicals) to determine the proper developing times and exposure index for your film. When you make these adjustments you will account for the Callier effect.
Time & tides wait for no one, especially photographers.
Over the years I accepted the writings of Ansel Adams about the so called Callier Effect. I didn't check the veracity of his statements with actual darkroom experience in my darkroom. When I got my first 4X5 enlarger, an old D2 I immediately scrapped the condensors and installed an Aristo head. Later I bought the Saunders 4550 VCCE and again opted for diffusion over condensor because for heavens sake it was Ansel who had stated that condensor enlargers were deficient because of the "Callier Effect". About a year and a half ago after reading the material that Jens Jensen had written about the quality of light on his site Jensen Optical or Durst Pro USA (the earlier site) I had the opportunity to buy a Durst 5X7 enlarger. My print quality immediately took a big jump upward...please understand that these were from negatives that had been developed to the Zone VIII density that Ansel had specified for diffusion enlargers...so if anything, my prints should have been too contrasty. That did not prove to be true. The sharpness and local contrast of my prints improved drastically. I would not have believed it until I tried it...but that has been my experience. In my experience in my darkroom the "Callier Effect" is a non issue.
While Ansel certainly helped move the practice of photography forward, I do believe today that he like most of us, had feet of clay.
I'll second that Donald, and I have similar views regarding the callier effect - I'ts a plus! Here in the UK I dont think Ansel Adams is as guru like as he (probably always will be) is in the US. There are fewer 'traditional' landscape photographers here that use him as a guiding light.
Well that is great you feel comfortable with condensers. I am sure many fine images have been made with them, as well as cold light/VC heads that are presented in galleries and museums over the years. Before the invention of the cold light head, what was there to use, condensers or contact printing.
I used to use condensers that had a piece of polarized glass and a diffusion filter over the negative which gave a more directional flow of light. But the condenser light source is 5-6 inches above the negative while the florescent grid of the cold light/VChead is less then an inch above the negative. This gives much more even illumination of the negative and less emphasis of grain and imperfections. I liked the results much better.
Time & tides wait for no one, especially photographers.
...my 2 cents...
Callier is real and coldlight works well with my negs. I use it for 120 film and up. I use a condenser, for speed reasons, for 120 film and down.
Changing light source types and enlargers at the same time is not a good test for Callier. Enlargers, like cameras, have issues of flare and glare. Most enlargers have a fair amount of reflected light bouncing around between neg and lens. This can contribute to contrast reduction at the print.
Someone mentioned how slow their VC coldlight was. I have heard this about ZVI and know that the Aristo VC heads are slow, too. I sold mine for this reason.
Finally, last I checked, I don't have feet of clay.
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Cold Light Heads
I have been printing for many years with a standard Cold Light. My negatives are mainly 120 PMK Pyro HP5 and 8x10 HP5 in HC110 contact prints. Although my first choice are always graded papers, I will occasionally use VC paper. Basic exposure times generally run between 20-30 seconds, which I would consider "normal."
Are VC Cold Light Heads that much slower ? I´ve never used one.
I'd say my Aristo VC was about 3+ stops slower than my Aristo V54. My typical exposure ran 30 seconds or more at 1 stop down with the VC. I like 10 - 15 sec exposures and several stop down. I print mostly 45 and 57 negs and mostly 810 and 1114 prints. Film is HP5+ in PMK.
About 6-months ago, I had a problem with my Zone VI head and associated timer. I recieved very good service from a tech named Jeff. However, I suspect you are correct about part shortages.
Metrolux Timer and Zone VI Cold Light
I ended up ordering a Metrolux II Timer Kit for a Zone VI Cold Light at Calumet, since I did not get an answer from Metered Light. The Zone VI Cold Light for my Beseler 23 has a Preheater/Stabilizer unit. I understand that is no longer needed with the Metrolux II ?
I guess the next step should be considering a new Cold Light Head, in case mine should fail. What would be your suggestion ? It seems the Aristo equivalent would be my best/only choice ?
Originally Posted by Peter Rockstroh
Peter, Although the preheater or 'thermo' is not required, you may find it helpful. It preheats the tube to a temperature that will give you high light output and thus make your exposure times shorter. I find this handy in the winter time. As my darkroom gets warmer and I switch over to AC from heat in my darkroom, I no longer use the preheater.
If your Z6 coldlight is working, why switch? If you're going to switch, then I think Aristo is the way to go. You will have to install a photo sensor in the Aristo coldlight, as they do not come pre installed as do the Z6. If you are going for an Aristo because you want V54, then ask Aristo about just changing the tube from Z6 to Aristo. Maybe. I don't know, but worth the question.