Split Filter Printing with a VC cold light head - observations and questions.

I recently purchased a Zone VI 5x7 VC head and for the past few months have been doing the split filter printing. After reading a few posts, I see that very few people are opinionated on the subject.


From what I've gathered most agree that the same results can be obtained via SFP vs. a single filter. Ok, perhaps that is true.

But my questions pertain more to using a VC head doing two exposures.....One hard, one soft...

I'm using the zone VI HEAD, with the Zone VI compensating timer.

When using a cold light and a compensating timer, don't the rules change for split filter printing? Due to the difference in the light output of the green vs blue tube?
I've noticed the time is dramatically different when using the green vs. the blue tube......one second with the green might equal 3 seconds the blue. Why is this? I allow for warmup.....(waiting for the "ready" light to illuminate before I make prints....and it can be frustratingly long)..

I've also read that two equal time expsoure of the green and blue equal one exposure of the together. How can this be true when using a compensating timer? Am I missing something?

I set my timer at two seconds, and have been doing initial printing making "two second" bursts....I say two seconds because that is what the timer is set on. But I've discovered, it is rarely the "time" indicated....

I"m following the correct procedures.....Doing the first test with just the soft, (sometimes the hard first...but does it matter?)...Deciding on my amount of time by judging the exposure on the test strip. Then laying that amount down on a new sheet, then redoing the test with the hard light.'

My intial reactions to printing this way have been very encouraging. I'm finding I rarely need to dodge/burn and the prints are looking pretty, pretty, pretty good.

One final thought or question.......When using this setup, with a compensating timer, it is completely unique from a one filter print. It seems plenty of critics of SFP claim that the same results can be had using one filter. But how is that possible when using different exposures of green and blue???

From my tests it follows that the green/blue sensitivities are related to the emulsion not the light source.

In terms of the 'one exposure equals two' I don't think anyone means that the time is the same. Just that it is possible to reproduce the results with a single color. But the math involves converting times into density and subtracting the two color densities to get a single color.

With a heated, but non-compensated, cold light it is important to keep the color sequence the same (becuase light intensity falls off the longer the lamp is on,and it takes a while to recover) If your system is well compensated, so that it is as stable as a halogen system, sequence should not make a difference.

Personally, if I were you I'd learn the split technique, but don't be dogmatic about it. Use that or use both colors together or mix and match. Don't be limited to one way of doing things. Use whatever technique winds up being easiest for you to get your results.

I use an Aristo cold light with a V54 lamp. I believe Aristo originally made the heads for ZVI, but I'm not sure. You don't mention the bulb, but the V54 is a blue green bulb, the first cold light sourse developed for VC use, as I understand it.
When I first started, I began by finding "normal" filter grades for existing negs, having printed previously on Seagull graded paper with a high intensity cold light bulb from the 80s.
As I got use to the filters, I decided to try SFP, and experimented with known images, comparing both split and single filter approaches. What I find is that many negs, when printed both ways, result in almost indistinguishable prints. Long range negs, however (of contrasty subjects) can be controlled much more discretely, in terms of subtle control of highlights (sky and clouds, for example), and deeper shadows. You can also burn more selectively. Sometimes, I hold back on a dark area during the low contrast filter exposure (usually the first one), then come back with the high filter exposure and achieve much better shadow detail. I can also give different parts of the image different ratios of the 2 filters, if needed, like if one end of the image needs more contrast, I blend the two exposures in cross direction, feathering left to right, and then vice versa. The attached image is done this way (actually, a scan of two 35mm 8x10 prints, joined in Pshop). The left end is higher contrast and darker, blended as described above. I could not have this kind of control without SFP.
The downside is that testing can take much longer, so I test strip a single filter first, before going to split filter. I'm surprised, though, how often I wind up splitting the exposure.

I think the difference in the sound of seconds is the pint of the compensating timer. It measures light units not time, so the light amount between each beep is the same.
As to the split /combined thinking, as an example Split -100 time units blue and 50 time units green. Combined- turn the green down 1/2 and full blue for 100 units together.
You will need to do test prints to figure the grades of the various combinations of blue and green and keep notes
( if you do let us know the results)
I decided it was simpler to keep doing splits.

tequilabong said:

Doing the first test with just the soft, (sometimes the hard first...but does it matter?)

Click to expand...

When making the test strips to determine the two exposures the order depends on the contrast of the negative:

• High contrast negative / low contrast print: soft green exposure first.
• Low contrast negative / high contrast print: hard blue exposure first.

Don't worry about the times for the two exposures - whatever you find gives you the print you want is the correct time.

There is an application note on the Darkroom Automation web site that may be of some help to you:
Split Grade Printing - A Measured Approach

I'm wondering if you have the Type I Zone VI enlarger with the single column for adjusting the lens stage? If so, it's much better to use this enlarger in the split fashion versus using both lamps together. This is because there's only one sensor for both colors. Having them both on with the compensating timer will maintain the same overall exposure, but it will not necessarily maintain the ratio between the two colors. So, overall exposure remains the same, but contrast can vary from one exposure to the next. Split printing sidesteps this problem, because each color will then be separately controlled.

Whether or not the enlarger is a Type I (or II), the timer appears to have different sensitivities to each color. (Maybe the compensating timer's sensor is different distances from each color's tube.) No matter. As long as one uses the same times for each color and split prints, both the contrast and exposure should remain constant. With the Type II enlarger (two columns to adjust the lens stage), one should be able to maintain both a constant contrast and exposure, whether or not one's doing split printing.

One advantage of split printing is that one can dodge and burn differently for each color.

I an not sure if this answers any of your questions, but here are my thoughts on split grade printing:

Like George, I use the Aristo V54 cold light, in my case fitted to an old Omega D2 enlarger. So it is not compensated, although it is heated.

I use split grade for all printing, except lith prints. It is a logical system to me, and I can see no advantages to jumping back and forth between single and split grade printing. As others have said, it reduces the need for dodging and burning, and makes dodging and burning more selective and precise when it is needed.

Sometimes my soft and hard exposure times are nearly equal, often I need a shorter soft time and longer hard time.

I almost always do the soft contrast exposure, then the hard. In my prints I observe that the soft contrast exposure affects shadows more than the hard contrast exposure affects highlights. Doing the soft contrast exposure first "pins down" the highlights where I want them, and the following hard contrast exposure "stretches out" the shadows where I need them to be without pulling the highlights further up the scale. The only exception to this is when I print a night photograph that is very high contrast. In this case I get the shadows where I want them first, then "burn in" the highlights with the soft exposure. I am not sure why it works this way, but it does for me.

Contrary to others' experiences, split grade printing does not take longer for me. When I did do single filter printing I was constantly frustrated by the circle of testing for time for a given filter, then needing to retest the time for the different filter, then maybe finding the new time and filter still didn't give the results I wanted. With split grade I get a straight print with the correct exposure in 2 test strips.