How to tell if your unsharp mask is good
I made my first attempts at unsharp masking this weekend and I must say it was probably the single most depressing and frustrating darkroom attempt to date. Are there any good web links out there giving tips on this technique. 90% of my google search turned up the usual links related to Photoshop unsharp mask (sign of the times.) My main trouble is judging exposure, development and contrast of the actual mask. I'm also assembling the thing with a loupe and lightbox which isn't that easy no matter what Barry Thornton says in his book. Also, does everyone use a glass negative carrier with unsharp mask? I don't have one so I was trying to improvise using Anti-Newton glass from slide mounts and its not working out very well. I'm at a stage where I want the sharpest looking prints possible, but this whole ordeal is making me rethink my goals!
Good Evening, Daniel,
In my extremely limited experience with unsharp masking, I have had similar frustrations. Perhaps "frustrations" is the wrong word; I simply regarded my attempts as experiments on a long learning curve and was glad to get one fairly successful result. If your main problem is judging exposure, development, and contrast, I'd suggest that you can probably reduce that problem significantly after a few more tries. Using stepped exposures on a single sheet of lith film should quickly indicate a basic required exposure. A couple of different developer dilutions (I think I used Dektol at either 1:15 or 1:30) should get you zeroed in on that variable. My biggest problem was the lack of proper registration equipment, so I was eyeballing it just as you were. I didn't find it impossible with a 4 x 5 negative, but it was somewhat tricky. I did not find a glass negative carrier necessary; I simply taped together at the corners the two sheets of film. I probably used my Negatrans carrier when I printed, but I can't recall for sure. (I really don't want to fight the dust problems of a glass carrier when a Negatrans gets a negative about as flat as glass could.)
Since my original masking efforts sometime last summer, I haven't tried it again, mostly just because I haven't had much need or occasion to do so. I haven't given up on unsharp masking, however, and I'll certainly try it again whenever a negative I really want to print seems to need it. I'm not sure, though, if I'll ever invest in the expensive registration equipment. I prefer to adjust my negative development to minimize the need for masking.
Unsharp masking requires specialized pin registration equipment and still has a steep learning curve. Give some thought to a technique called Semi-Stand or Minimal Agitation. THis technique will effect the same result you are looking for during the development process. Doesn't help with film which has already been processed but cold prove extremely useful if you are willing to spend some time dialing in to your likes. Steve SHerman
Unsharp masking certainly benefits from having pin registration equipment but it isn't absolutely necessary. In fact no one makes pin registration equipment for 35 mm, which I see that you use.
There are several considerations...the first is the density range of your original camera negative. The second is the density range of your unsharp mask. Without knowing what your camera negative density range is I can not begin to tell you what the unsharp mask density range should be. Typically the peak density of an unsharp mask is .18-.35 but again this varies with your camera negative.
I would say that the appearance of an unsharp mask is typically quite indistinct. By that, I mean, that it would appear to be very low density and very low contrast. The sharpness should be very soft. The danger is having too much density and too much contrast. High mask sharpness makes it that much more difficult to register the negative and the mask.
I began using unsharp masking with Cibachrome years ago using the Gepe glass anti-newton slide mounts...It worked quite well...without pin registration equipment.
Minimal or semi stand agitation does not provide what unsharp masking provides. I use both minimal agitation and unsharp masking, for different applications...the effects are totally different...not to be confused or interchanged indiscriminantly with each other.
Check with Kodak. They use to do a pamphet on Un-sharp masks. If not then look for the book "Dye Tranfers made easy" or Ilford's Advance printing techniques for Cibachrome. In these is some information for masking since masks play a major part in Dye Transfer prints.
I used to make masks for a commerical lab. I used Kodak's Pan with Kodak's HC110 at solution 8 or higher. You need to test with a stouffer step wedge.
I have a copy of the ilford tech folder. I can send you copies on makig masks. Just PM me with your address and I'll send it to you. You mask need to be thin to the eye. Like a underexposed under develpoed neg.
You can get some of the same results of masking using a Pyro developer with out the hassle of registering neg to mask. You should look up Christopher Burkett, the master of masking.
He has it down to an artform.
"We are what we repeatedly do. Excellence, then, is not an act but a habit"
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It is important to use a pin registration system such as the one made by Alistair Inglis that can be found on:
http://www.alistairinglis.com/inglis...rp_masking.htm . However, a better site that demonstrates this system (and a more detailed, perhaps more precise) procedure can be found on http://www.largeformatphotography.info/unsharp/ .
The important innovations of the procedure below is the use of the turntable and the using two different strengths of developers.
1. Punch negative emulsion-side up (i.e., the original and the mask). (I use Arista 125)
2. Set enlarger height for an 11x14 print (make a witness mark on column so setting can be repeated).
3. Underneath, place a 10 ½” turntable (like a Lazy Susan) as far off-axis as possible (i.e., in the corner of the area illuminated by the enlarger light).
4. Using the original negative and the unexposed film for the mask, make a “sandwich” both with emulsion sides down.
5. Expose the “sandwich” while rotating the turntable. Run about 3 -test negative to determine exposure. For the ASA 125 film I use, the will be in the range of approximately 8-seconds @ f/32, depending on the density of the original negative).
6. I develop the mask in a Slosher (i.e., a 6-cavity tray that fits into a larger tray. Develop for 2-minutes 30-seconds while gently rocking tray agitating vigorously for approximately 5-seconds every 30-seconds using a 1.7% solution of HC110.
A good mask should produce a faint positive image with details that extend only into the middle values of the image.
Note: I’ve found that Howard Bonds more precise method using a densitometer in not necessary. Use your eye to check for “edge effects” and note the reduction for the need to do as much burning of skies.
In the long run, you can save time by making two masks: One as described above and another using a stronger 1.56% HC110 solution of developer. Compared to your straight print, a good mask will kick the contrast up at least one grade (maybe two). Therefore a negative that would be a good candidate for unsharp masking (USM) would not print higher than a grade3 ½ or 4.
Originally Posted by Daniel Lawton
The difficulty and time of production in getting good unsharp masks is what has kept me away from this technique, which admittedly produces some lovely results.
However, while the unsharp masking advocates will undoubtedly dispute this, I'm not sure the gains are worth it when compared with another technique(s) which can accomplish nearly as good results, if not as good.
I'm referring to the technique of split-grade printing on VC paper, combined with divided development. The split-grade technique (two exposures, one at full magenta, one at full yellow if using a colorhead or one at highest contrast filter and one at lowest contrast filter if using filters) yields prints with greatly improved local contrast that make the tones "sing" in ways that are quite similar to unsharp masking. Divided development provides further assistance in consistency and tonal control. The learning curve for both techniques is much shorter (see my article on Divided Paper developers in the Chemistry Recipe section), and I think you'll be very pleased with the results.
"In the long run, you can save time by making two masks: One as described above and another using a stronger 1.56% HC110 solution of developer. Compared to your straight print, a good mask will kick the contrast up at least one grade (maybe two). Therefore a negative that would be a good candidate for unsharp masking (USM) would not print higher than a grade3 ½ or 4."
I don't understand the reasoning behind this statement. It is at odds with my experience. Since an unsharp mask is a positive of the camera negative, it compressed the density range of the camera negative. If the camera negative is already of sufficiently low density range to require printing at a grade 3 1/2 to 4 then an unsharp mask will compress the camera negative density range still further to the point that there will be insufficient offsetting contrast increase available through filtration.
I would say that the best candidate for unsharp masking would be a camera negative that would require printing at a grade 1-2. In terms of density range this would be a camera negative that ranges from 1.25-1.40 depending on the light source of the enlarger.
I think that densitometric evaluation is probably as important to unsharp masking as pin registration. I own both a pin registration system and a densitometer. Given the choice of one, I would choose a densitometer.
That has been my experience.
I don't believe that I agree with the your assessment that split grade printing enhances local contrast in the same way that unsharp masking does. I have done both quite often.
Originally Posted by Maine-iac
The reason for my disagreement, based solely in my experience, is that split grade printing does not alter the density range of the camera negative in any way. Whereas unsharp masking does effectively compress the camera negative density range to allow subsequent printing of negative/mask with higher contrast filtration. The effect is that in the process of increasing overall contrast to desired levels it also increases local contrast within the image. That is one of the noticeable results of unsharp masking.
Now split grade printing is a beneficial means of printing some negatives. It allows very good control of burning some specific regions within a print at higher or lower contrast but it does not affect the overall contrast in the same way that unsharp masking does. I do find that sharp masking does allow even more control in this regard then split grade printing.
What often times occurs within the photographic community is disagreements over procedures based in the mistaken belief that one process in inherently better then another process. In my opinion this is an unfortunate orientation. Each of the processes whether that be unsharp masking, sharp masking, split grade printing, pre or post flashing, contrast enhancement masking, or contrast reduction masking are all individual tools and the photographer/printer needs to learn each of these tools in order to determine when they will best serve his production of a meaningful print.
Donald - Yes, a grade 1 or 3 is fine. My statement was that the neg should not be greater than one that will print on grade 3 12 or 4 since an increase in constrast will be found when you sandwish the USM with the original negative.
My experience parallels your regarding split grade printing. This method does not improve local contrast as much as USMs nor does it in any way enhance apparent rpness.