Split grade printing: the key to success
There is a new application note on split-grade printing on the Darkroom Automation web site.
The article stresses that the key point in getting split grade printing to work is the necessity of treating high contrast prints differently from low contrast prints.
In this context high contrast prints are those made with a longer #5 exposure, and low contrast prints are those made with a longer #00 exposure.
When split grade printing in the traditional 2-test strip method:
- High contrast prints must be made with the black-point/high contrast test strip made first.
- Low contrast prints must be made with the white-point/low contrast test strip made first.
The article gives detailed information on split grade printing with a meter. It presents a simplified approach in which a simple graph gives you all the information you need to find the correct filter ratio. The complete contrast response of a VC paper - over all filtration settings - can be found with just three prints of a step wedge.
Last edited by Nicholas Lindan; 12-31-2008 at 06:06 PM. Click to view previous post history.
Looks like a well thought out system.
I agree with you 100% on the pros/cons of split grade. Especially #1 "Only works with prints with pure whites/highlights and blacks." I recall last year when I was starting split-grade, I saw an exhibit at the Cleveland museum (I believe from their own collection) and I specifically paid attention to blacks and white. Most prints did NOT have full black or white.
Actually, the purpose of the meter and the application note was to do split grade printing with NO test prints.
Originally Posted by ic-racer
You meter the negative contrast - from the graph this directly gives the ratio of filtered exposures.
The key point in the system is that low and high contrast prints are treated in different, though symmetric, fashion.
If the #5 filter exposure predominates (low contrast negative/high contrast print) then expose with the #5 filter for the metered shadow exposure. The #00 filter exposure is less by the filter ratio.
If the #00 filter exposure predominates (high contrast negative/low contrast print) then expose with the #00 filter for the metered highlight exposure. The #5 filter exposure is less by the filter ratio.
Thats it. No test prints. One chart. Of course you can do the same thing with the meter and graded filters and save a lot of palaver.
The downside to split grade is, as you have mentioned, that there is no direct placing of any mid-tones or mid-tone contrast, and mid-tones are really where the image interest lies and printing control should reside.
The upside to this method of split grade is that charts can be developed for any paper with 3 shots of a step tablet.
But that upside is only because the system's only information on a paper's response are its black and white points.
This method reinforces the anecdotal posting on APUG that for printers making the low contrast test strip first for the highlights find that split grade only works well for them when printing contrasty negatives. On can only assume those who find it works, and make the black test strip first, normally have low contrast negatives. Those who find it works either way make normal contrast negatives, and could save themselves a lot of bother by printing with no filtration at all.
Hmmm. For under-lens Ilford filters with a PH212 bulb/condenser light source, equal exposures with #00 and #5 filters give a 3.8 stop / 1.14 log / 114 ISO (close enough to 120 for government work) contrast.
Originally Posted by ic-racer
Of course, with a color head, that ratio is going to be different as the full-yellow and full-magenta filter settings are going to have different filter efficiencies from the Ilford filters.
The 2:1 ratio for soft/hard exposures for normal grade with a color head makes sense if one assumes Ilford added 1 stop of ND to the #5 high contrast filters, which they may have done to keep the printing times for the highest contrast grades at 2x the softer grades. If the same amound of ND was dialed into a color head for the magenta exposure then equal exposures would give a normal density print.
Last edited by Nicholas Lindan; 01-04-2009 at 12:28 AM. Click to view previous post history.
Nicholas: I am confused over your repeated references to low contrast negative/high contrast print, or vice versa. Is that meant to mean that if one has a negative with a density range that produces a lower contrast print than desired with no filtration, or perhaps equal low/high filtration, one would expose through the high contrast filter first, but with the low contrast filter first if the opposite were true?
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Ralph Lambrecht (darkroom magic) had a guide like that to be used with the Ilford EM10 enlarging meter. I found that you simply expose using the #5 filter to make the blacks black, and then with the #0 filter (I have no 0000) for the midtone (by experience)
Mama took my APX away.....
Now, try that with a really contrasty negative and I think you will find it doesn't work as well - and that doing the #0...0 exposure first and then determining the black exposure gives a more controllable result.
Originally Posted by titrisol
The idea that the printing technique needs to change depending on the printing contrast is briefly mentioned in Beyond Monochrome but then seems to be dropped from the subsequent examples and advanced techniques. The book also does not specify the dividing line. It isn't really a sharp demarcation but a region between -1 and 0 on the graph below. However, an arbitrary point at equal filtration works well enough.
I think this point is the key to getting split grade to work, and is the reason that many people find 'it works about 1/2 the time'.
There are many ways to skin a cat and even more ways to make a very good print. Some are better than others for some people. There is no magic path, and the application note certainly isn't pretending to be THE METHOD, it's just one method among many, and one that some printers may find useful and fitting to their temprement.
Last edited by Nicholas Lindan; 01-04-2009 at 02:09 PM. Click to view previous post history.
Low contrast negative: flat, mushy, grey on grey ...
Originally Posted by FirePhoto
So a high contrast print (one made with high contrast filtration or paper grade) and a low contrast negative make a finished photograph with normal contrast.
You are right, it does seem a bit confusing in retrospect: "high contrast printing technique" might be a better term. "High contrast print" in this context doesn't mean the finished print is high contrast. Of course, you can make a high contrast print from any negative - it's the printing technique that matters, not the negative contrast.
Thanks for pointing it out.
Last edited by Nicholas Lindan; 01-04-2009 at 11:24 AM. Click to view previous post history.
Duh... Now I see!! For some reason I was interpreting the method as placing the large step wedge on the paper when making the exposure...Never mind...
Originally Posted by Nicholas Lindan
Good pickup on that graph. That graph I posted is actually for a bare W45 Aristo, therefore somewhat distorted, compared to other light sources.
Hmmm. For under-lens Ilford filters with a PH212 bulb/condenser light source, equal exposures
with #00 and #5 filters give a 3.8 stop / 1.14 log / 114 ISO (close enough to 120 for government work) contrast.
All the graphs and colored lines make me dizzy. Guess that's why I like Fred Picker for film exposure and Les for printing.
Pretty basic, even if you eat up a couple of sheets of film or paper.
Last edited by mikebarger; 01-04-2009 at 04:23 PM. Click to view previous post history.