When I was in college and doing an independent study in B&W printing, I found a lot of helpful ideas in Carson Graves' "Elements of Black and White Printing," including split grade printing. Once I got the hang of it, it became my default. Very versatile and it allowed me to make a lot of prints I don't think I could have gotten any other way.
Bob - with a cooperative decent neg, ordinary "white" light is, for all practical purposes, a multiple filter, and one simply treats the VC paper as if it were graded in
this respect. Then if needed one can go back in and tweak the highs or lows or whatever split-print mode. Personally, I'm more likely to do just the opposite because
I'm trying to optimize the toning color primarily of the high-contrast layer, so I'll dev my negs for printing mainly thru a deep 47 blue filter or direct blue in the additive colorhead. This is really a different topic, adjunct to mere contrast characteristics, but I'm very nitpicky about final image tone and this gives me another tool of expression. So I end up mostly using blue light, and maybe or maybe not tweaking things with a bit of green or white. But I only do this with large format sheet film, where I can carefully control specific neg dev in the first place. With roll film I tend to work more conventionally, and just use colorhead settings. So we make these rules, then learn how to break the rules. It's all fun.
I have never used the extreme low and High filter , I always start with a mid filter or a filter that is most appropriate for the scene, I then build up with usually the 5 filter to create the contrast overall I am looking for.
I have detailed my method here and on APUG , using a single filter IMHO is a compromise with dodging and burning that is insufficient. Remember the days of graded paper where the most you could hope for was a 1/2 grade boost or drop by doing split development.
Characteristic of graded paper were the compromises, either good shadow detail with heavy burned in highlights that eventually were soft and muddy, or brilliant midtone to highlight with massive clogging of the shadow.
By manipulating the negative with filters that compliment regions one can bring out the full tonal value. IMHO of course.
others may vary with their experiences.
I have only been printing for about 5 years. Most of it has been with dichroic heads. About 2 years ago, I got a mint 23C VC head, which I like better than dichro. There have been several negatives that no matter what I tried, I was not able to get the contrast I wanted, regardless of filter(s) and exposure time combination. A few months ago, I tried my hand at split grade printing and, I have to say, it has really opened the door to getting good prints out of what I had thought to be useless negatives. It is so easy too, I don't know why I was so intimidated by it before. There is so much more control using split grade than single filter printing. I am definitely a convert!
In the past few years I have used two techniques for contrast control. One is split printing; expose with the "soft" lamp, then expose with the "hard' lamp. This is a technique I use with a very high contrast negative. I also refine a print exposure by pseudo-split printing. My enlarger has both the soft and hard lamps on separate rheostats. If I have a good print at 30 seconds with both rheostats at 50%, I can get exactly the same print by exposing with the soft lamp only for 30 seconds, followed by the hard lamp only for 30 seconds; both on for 30 seconds or each on separately for 30 seconds results in the same exposure. If I have the highlights exposed correctly using both lamps together [30 seconds at 50% gain], I can make a pilot print with the soft lamp for 30 seconds @ 50% gain, then make a series of test strips over the first exposure with the hard lamp @ 50% gain to see what a little less or a little more hard exposure will do to the print. The test strips may be from 21 second to 36 seconds in 3 second increments with the hard exposure. My next print may be soft lamp only for 30 seconds followed by the hard lamp only for 24 seconds; the detail in the low values are better with the slightly less hard lamp exposure. I use the version of split printing to refine by prints.
Paul
The suggestion in post #4 is an excellent one. WBM 2nd Ed. is available through Amazon:Originally Posted by spacegoose
http://www.amazon.com/Way-Beyond-Mon...ond+monochrome
It will show you that, yes, the tone from the first exposure will be affected by the second exposure to some degree. It will also explain that the reduction needed in the first exposure depends on which of the two exposures was done first.
I definitely agree. Way Beyond Monochrome is an excellent book, and should be required reading material for B/W film photographers, along with the Ansel Adams' trilogy. I have learned so much from it, and I still stand to learn a lot more. This book goes into such great detail about photographing, exposing, developing, printing, contrast control, etc., it is definitely a must read.
I first gave split-grade a try a few years ago, and once I got the hang of it I've never gone back to single filter printing. I've found that the combination of split-grade printing and f-stop timing make me much more efficient in the darkroom. I find that with two test strips at (0 or 1/2) and 5 I am able to produce a viable workprint with the first full-size print. While this is very nice, as others have said the real win with split-grade printing is the ability to emphasize certain areas of the print with differing contrasts; this is a wonderful tool to have in your back pocket. The discussions and pics in WBM really make this point well. You should get this book - it has _way_ more stuff than just split-grade printing.
Why do I use grade 0 or 1/2 for the soft limit? I read somewhere that most modern VC papers don't have only two emulsions sensitive to different colors; they have three (or more), and each emulsion has the same characteristic curve. What the filters do is modify the effective exposure experienced by each emulsion: a grade 5 filter will make each emulsion experience the same exposure, and thus the resulting characteristic curve for the print will be characteristic curve of the emulsion. Other grades will decrease the effective exposure for different emulsions, separating the characteristic curves along the exposure axis. Thus, the density of the print (which is the sum of the densities of the individual emulsions) will have a longer scale.
From my reading it seems that at grade 00 the emulsion exposures could be so separated that the ~linear parts of the characteristic curve don't overlap, and there will be flat portions in the overall characteristic curve. IIRC, one of these flat portions (i.e. increased exposure does not significantly change print density) occurs around where we put skin tones. So, I use grade 0 or 1/2 to make sure there is an overlap.
This also makes me wonder about the design of LED light sources. LEDs tend to be pretty monochromatic, which would be fine if the peak intensity is at the peak sensitivity for the emulsion. This could work for 2 emulsion VC paper, but is there a thread about designing for the 3 or more emulsions that seem common with current VC papers?
What Jerry states is true, but only as a generalization. VC papers differ somewhat. I find that with some of them you need at least token exposure of "both" emulsions in order to achieve DMax. With certain others, that's not the case. What would probably takes me years to understand properly and correctly explain seems to take mere minutes to achieve in the darkroom. I don't even care what "grade" I'm allegedly aiming for, unless I happen to be shopping for true graded paper. But
regarding color of sensitivity - I print VC papers with three completely different kinds of light sources: A V54 blue-green coldlight (sometimes selectively used thru
deep green or blue separation filters), an ordinary CMY colorhead, and my relatively narrow-band true RGB additive colorheads. I can achieve the same result with
any of them. The various VC paper brands don't seem to be all that fussy. But I have no experience designing with LED sources.
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