View Full Version : Arist cold light

ric YAMA
20-Sep-1999, 20:32
I am trying to make some black and white prints using Arist cold light(V54) on O mega D-2 enlarger. And, I am wondering if I can use multigrade paper with Ilford filter which I have, because it seems that the light from Arist light source is too cyan or blue to control contrast of prints. Actually, I'd like to get very strong contrast such as grade 5 or 6 for my prints. Is it possible for me to get such high contrast using the Arist lamp?, or should I use graded paper? Any input will be greatly appreciate. ANAUSAGI

N Dhananjay
20-Sep-1999, 22:09
Typically you will have no problem getting hard contrast with VC emulsions with cold lights. VC paper has two parts to the emulsion - one sensitive to blue light which is responsible for the hard contrast and one sensitive to green light which is responsible for the soft contrast. The filters for use with VC papers were designed for tungsten sources. Since cold lights have a higher blue content, they will give you higher contrast with the same filter than would a tungsten source. The contrast ranges are unequally spaced as well i.e., moving from filter 4 to 5 has less of an effect than going from 1 to 2. The biggest problem is the fact that a normal density range negative will need a filter as low as 1/2 or thereabouts to give you a similar rendition a a filter 2 with a tungsten source. This gives you very little leeway on the soft side. Filter 0 is soft and filter 00 is extremely soft with nothing in between. You can patch these holes with additional filtration. Use either additive, around 30CC green, or subtractive 20CC to 50 CC yellow. All of this is moot if you're looking for hard contrast. VC will give you all the hard contrast you need with cold lights. Good luck. DJ

ric YAMA
20-Sep-1999, 23:50
To Mr. N Dhananjay Thank you for your advice. I have one more question. Is there any chart for cold lights which tells what filter I should use for the particular contrast which I want on the web site or from Arist?? For example, when I want to get grade 5 contrast on the multgrade paper(Ilford MGF), the chart tells what filteration I should such as 20M or 50M. I have no idea what filteration I should start at. So, if you know any chart or article about the contrast control with cold lights, please let me know. Thank you very much. ANAUSAGI

Alan Gibson
21-Sep-1999, 08:16
"The Variable Contrast Printing Manual" by Steve Anchell, may contain the information you want.

Robert A. Zeichner
21-Sep-1999, 08:21
There is not necessarily an obvious relationship between paper grades and filter numbers. The best way to determine what changes might be expected from different filters is to run a series of tests using a Stouffer step wedge. This will allow you to establish a "normal" filter for your average negative as well as determine the necessary exposure compensation needed with different filters. Stouffer Graphics is in Indiana, I believe. Perhaps they have a website where you can find helpful info regarding their products. There is quite a good compendium of articles on printing with multigrade paper that was published by the folks at Photo Techniques magazine. This too, should prove a help to you. Good luck.

Bryant Urstadt
21-Sep-1999, 11:09
As for a chart for using Ilford's paper with cold lights, you should check their web site. They have very detailed information about using their paper with a cold light and a 40Y filter.

N Dhananjay
21-Sep-1999, 11:35
Printing step wedges are perhaps the best way to go about doing your own calibration - I think the Stouffer 31 step (steps increase in 0.1 density increments) costs about $30 or thereabouts. Essentially, when you use VC papers with cold light, you will need to calibrate to your light source. This is because the multigrade filters are all calibrated to tungsten sources. The only way to figure out what contrasts you're getting is to print step wedges using the various filter grades and compare that with what you get from your point of comparison - either a tungsten source or from graded papers. As Robert points out, there is no obvious relationship between filters and paper grades. There is also no obvious relationship between grades obtained with the same filter from tungsten sources and cold lights - it probably depends on how blue heavy your cold light is. All the stuff in my previous answer - unevenly spaced contrast grades etc are based on these tests that I ran on my setup. DJ

N Dhananjay
21-Sep-1999, 11:44
I must apologize - I just noticed you mention that you use a V54. My understanding was that these tubes were optimized for VC papers by incorporating blue and green light which you could control. You shouldn't have to do a song and dance then. You should be able to get softer or harder grades just by dialing in more green or blue light (or at least, that's what I understood from a cursory read). There was a recent thread in the B&W forum which might be of some help. In any case, if you want harder contrast, you basically need to dial in more blue light (I'm still preesuming you can dial in with the V54, else you filter in more blue by using the magenta/higher end multigrade filters). If you want softer contrast, increease the amount of green light. Printing step wedges in any case is probably a good idea becausee it will help you see the contrast ranges you get relative to something which you have already worked with (and know how it works). DJ