Advice on printing w/ cold light head & filters

[brian_turner2]

I've been plugging up the boards recently with questions about

using a cold light source. I apologize. I've recently switched from

a condenser, so this is like learning to print all over again for me.

It seems that each time I learn something on here, each new

printing session brings a new variable into the equation, or

some slight modification to my enlarger. Many of you have

helped me tremendously, and I thank you!

 

Now I have a new situation that I would like to throw out to you:

 

First off, I'll tell you that I'm printing on Multigrade Fiber paper,

using variable contrast filters, just as I always have. One thing

that I have noticed about printing with this new cold source, is

that the differences between say, two seconds and four seconds

are like night and day! Much more so than with a condenser.

Also, the differences in filters are more dramatic as well, which

brings me to my main question: why is it that when I go up in

filters (more contrast), my exposure time seems to be less?

When I was using the condenser unit, if I moved from a #2 filter

to a #3, my exposure time needed to be quite a bit longer, which

is just the opposite of what I experience now. Is this normal, or

am I experiencing something very strange here? What could be

causing this? Does it have something to do with the way the light

reacts through the "red" in the filters? I noticed that the dark red

focusing filter that I used to use with the condenser doesn't work

with cold light. No light passes through it at all. I do have the

Aristo V54 bulb which is supposed to be for VC papers...

 

I'm not terribly frustrated, because I know it will take some time

learning this new set-up, and I have had some amazing results

when I happened to get it right. I just want to know if this is to be

expected, because right now, my assumptions have been totally

off! -thanks!

[brian_turner2]

-what I meant to say about the red "focusing" filter was that no

light is visible through it- that is, I can't see any image on my

paper while I am focusing. Before, I could see the image without

it actually exposing my paper. What I wrote above seems kinda

silly!

[richard baznik]

I made the switch from condensor head to Aristo cold light about four years ago, and have had no regrets. One of the dramatic differences between the two systems is that my cold light (not the same model as yours) is considerably weaker than the condensor light source. I think that would explain why you can't see an image through the red filter.

 

As for the change in the exposure curve as one goes up the contrast scale, that was not my experience: a grade 3 filter has always required less exposure time than, for example, a grade 1.

[scott_walton1]

I have been printing with Aristo Heads for about 12 years now and won't go back. The blue wavelength is pretty much visually cancelled out by the red viewing filter. My suggestion there is to forget about the filter and just compose without it on the easel. You can use other print developers to tweak your prints by using Dr. Beer's developer which is a 2 part print developer. Bath A is low contrast and by adding incremental parts of B bath, you can raise the contrast chemically. I found myself printing with a 1 and 1.5 filter more often than not when I went to cold light. As far as the differences of printing times... you are getting into the finer parts of printing and if you don't have a timer that gives you 1/8 or 1/10ths of a second, get one! After awhile you wll see a good difference in a 1/4 second exposure change if you don't already. Another thing I realized about printing effectively with cold light is that I had to tune my negatives for it... ergo exposing more for a meatier negative. A 2 bath film developer works wonders for this. I use Divided D76 and Diafine for this reason. They are both very simple to use being that (with the older emulsions) all you have to do is develop in bath A for 3 minutes and Bath B for 2-4 minutes going to a water rinse and fix as usual. No blocked up highlights (compensating developers) and very fine grain!!! Diafine is a higher acutance developer than DD76 and has a GREAT look to it. I do have recipes for all the developers I talked about if your interested in them in a PDF format or you can get DD76 from Photo Formulary. Diafine has been around for ages and you should be able to find it at a good camera store.

Cheers,

Scott

[dave_schneider]

I made the switch several months back from a condensor with 75 watt bulb on my Omega D5 to an Aristo V54 source. My experience is the Aristo provides more illumination than the condensor source, I'd estimate about 1/2 stop, on a 6x9 negative, less difference with 35mm.

 

What really helps in comparing print times or even in judging changes in exposure to achieve your desired result, is to think in terms of stops. There are timers that do this for you but my solution was to simply make a chart in MS Excel with 1/8 stop increments. When you do this you relize how significant a one second change is between 3 and 4 seconds and almost insignificant between 10 and 11 seconds. The f-stop printing makes it easy to add filters, change lens f-stop, change print size or even paper type.

 

The cold light has been very easy to work with using grade filters. I usually print with 1/2 grade more contrast filter than I did with the condensor. I think the tonal scale is more even with the cold light but that's a very subjective assessment. I'm sure I could tweak film development/exposure/printing with either light source to match results.

[maury_cohen]

Brian,

The instructions that I based my cold light use on reccommended using a slight yellow filter, at all times, (mounted directly under the light itself) to correct the light source color to a basic contrast. From there, using Ilford Multigrade paper, I used the guide that comes with the paper which cleary indicates the relative ISA sensitivity when using the particular contrast grade filters.

[chuck_pere]

One thing I notice with my V54 is that the spacing is not as even as condensers. I see a big jump from 3 1/2 to 4. Because of this I have to do more split filter printing to get between the two discrete steps. Or you could use two bath developer solution. Now I'm thinking that maybe for a cold light total split filter printing is the way to go. Do separate exposures through 00 and 5 filters and vary times for contrast changes. This would find the contrast you want with no worries about filters steps. You probably also should run printing tests with a step wedge and the different filters to calibrate your system. I keep putting this off.

[george_nedleman]

I use an Arista with V-54 tube and followed Howard Bond's Article in Darkroom Tech. Use a step wedge and compare the range you get with each filter grade to the set range for each "paper grade". Throw away your red filter. As far as I'm concerned it takes about 10% exposure change to make a real difference. If you're in the 2-3 sec range I suppose an electronic timer is in order but with my 6x7 @ F16 or 22 Ilford MG FB 8-14 sec is normal.

George Nedleman

[heninger]

Ok, so this thread is a bit old, but someone mentioned an article on the V54 lamp that arista makes.

 

It is at:

 

http://www.aristogrid.com/Tech01.htm