How to tell if your unsharp mask is good

Discussion in 'B&W: Film, Paper, Chemistry' started by Daniel Lawton, May 15, 2005.

  1. Daniel Lawton

    Daniel Lawton Member

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    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!
     
  2. Konical

    Konical Subscriber

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    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.

    Konical
     
  3. Steve Sherman

    Steve Sherman Subscriber

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    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
     
  4. Donald Miller

    Donald Miller Member

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    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.
     
  5. Robert Brummitt

    Robert Brummitt Member

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    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.
     
  6. hortense

    hortense Member

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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_unsharp_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.
     
  7. Maine-iac

    Maine-iac Member

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    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.

    Larry
     
  8. Donald Miller

    Donald Miller Member

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    quote

    "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.
     
  9. Donald Miller

    Donald Miller Member

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    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.

    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.
     
  10. hortense

    hortense Member

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    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.
     
  11. Donald Miller

    Donald Miller Member

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    Hortense,

    I am sorry but I still do not follow your thinking on this...an unsharp mask does not increase the negative density range (contrast) of the camera negative. It decreases it.

    Since the unsharp mask is a positive image of the camera negative it offsets the density range of the camera negative. The way that I think about this is...the unsharp mask has density where the camera negative has low density...that in effect decreases the density range of the camera negative when the mask is combined with the camera negative at the printing stage. That is why when we print the negative/mask sandwich that we are increasing the contrast filtration on the enlarger to offset this compression that the USM brings.

    So the best negative for unsharp masking would be one that has a higher then normal density range (contrast) and would, when printed alone, be printed at a grade 1-2.

    A negative, that by itself, would be printed at grade 3 1/2 or 4 would have a lower then normal density range (contrast). If we were to take this negative and prepare an USM the addition of the mask we effectively lower the density range (contrast) of the negative still further. Once this were done, we would no longer have any more filtration to dial in to offset this lower contrast that the USM/negative sandwich would exhibit.
     
  12. Jose A Martinez

    Jose A Martinez Member

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    unsharp mask is not about sharpening

    An unsharp mask is intended to improve the local contrast, not to produce a sharper image. The "sharper look" of an unsharp masked image is a "side effect" due to the increase of the acutance, product of better local contrast and a microscopic line created by the shadow that takes place between the layers of the mask.
     
  13. Kirk Keyes

    Kirk Keyes Member

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    Donald, Hortense and you are in agreement.

    He is just suggesting that if you have a neg that prints without a mask at grade 4, and then you add a mask, which as you correctly say, lowers the practical overall contrast of the neg/mask combo, then you will then be forced to use a paper with a grade higher than 4. He is recommending that one not put themselves into this position.

    As you say, you will probably have better results if you develop the original neg to a higher contrast range if you are going to be using a mask.
     
  14. Daniel Lawton

    Daniel Lawton Member

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    Thanks everyone for the replies. I did check out the Alistair Inglis site regarding pinregistering systems but they only make them for large format 4x5 and up. I made a second attempt and the results are better but still a ways off so I'll give it another go later on. Dan you make a good point about "apparent" sharpness being a side effect of contrast reduction. It is this sharp "look" I am going for. In order to simplify the process I have been using Ilford ortho for my masks so I can process it under a safelight and I am processing it just like paper using extra-diluted Dektol from last weeks printing session. My spacers have simply been fixed out clear pices of film.
     
  15. hortense

    hortense Member

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    Thank you Kirk.
     
  16. Maine-iac

    Maine-iac Member

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    Donald,

    I don't claim that there are no differences between the contrast control available through unsharp masking and split grade printing, only that for me, the gains have not been worth the expenditure of time and effort.

    It was not the convenience of burning in different parts of a neg with different filters that initially led me to adopt split grade printing, although that certainly is one of the main benefits. It was the actual difference in the appearance of the tones, particularly the midtones in the print. I could see a difference in a midtone in a print made with a single exposure with a combined Magenta/Yellow filter pack and one made with a full exposure through each of the filters in sequence (doesn't matter in which order). To my eyes, the midtones had a "glow" about them that they didn't have in single exposure printing. It might be just my imagination, but I don't think so. A corollary benefit for me has been the sheer ease of getting a good work print on the first try so frequently.

    So I might be motivated to adopt unsharp masking for prints where I couldn't get the results I wanted (and suspected I could get) with my split grade method, but for the most part, I've been content with my results. I do occasionally make use of local or global bleaching to raise a particular highlight value.

    Larry
     
  17. Donald Miller

    Donald Miller Member

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    Larry,

    While this is taking this thread away from the original question. I will respond to your post that was directed to me.

    I will reiterate, that I would hope that this is not a potential conflict arising from the belief that one printing method is inherently better then another printing method. As I said in my earlier response to you, I think that all of these are tools that would beneficially be adobted to specific instances. It is up to the individual photographer to learn the tools and when to apply them.

    I was thinking about this yesterday. I don't recall anything ever having been written that outlines the benefits of each of the printing procedures. Both their beneficial effect and their offsetting detrimental effect. Under what ciricumstances to use them based upon the characteristics of the negative and the characteristics of the printing paper. Perhaps you have. If you have please let me know because I have thought of writing a procedure for that purpose.

    My thoughts on writing something would follow along the following questions....what are the benefits of unsharp masking? When would it be used? What are the beneficial effects? What are the detrimental effects?When would it be recommended? Under what circumstances would it would not be recommended? What are the differing effects of contrast reduction masking as opposed to print pre flashing?...for another example. Additionally, determining the same set of criteria for each of the other printing procedures/manipulations including split grade printing, contrast enhancing masking, contrast reduction masking, pre and post flashing of the paper, sharp masking etc...

    This material, if I were to write it, would be supported by densitometric documentation of the actual effects of each of the processes.

    Let me know, if you will, your thoughts on this. Would it be something that would help?

    Best regards,
    Donald Miller
     
  18. fotophox

    fotophox Member

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  19. Kirk Keyes

    Kirk Keyes Member

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    Donald, I think this would be a landmark piece of photographic writing if you were to do that. I can't think of a book or article where all these things have been compared, especially if you do it in depth. I say go for it!