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Thread: Unsharp masking

  1. #1

    Join Date
    Oct 2008
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    19

    Unsharp masking

    Hi

    I've never seen a print that I've known to be printed using an unsharp-masked, let alone a comparable pair of masked and unmasked prints. On the other hand, people who do unsharp masking often rave about how wonderful it is, so I thought I would experiment.

    I chose an image that had been developed in 510 pyro. I made a mask using 4x5 Ilford Ortho Plus film. I used a single piece of clear sheet film as a spacer. I exposed it under my enlarger after placing a sheet of drafting film on top of the image neg to diffuse the light. I developed it in Rodinal, experimenting until I got what I expected to be a "fairly strong" mask. On examining the mask with a loupe, I could see that it is definitely not sharp.

    Then I made a print and compared it with a print made without using the mask. To get a comparable image using the mask, I had to increase the paper contrast from grade 2 to grade 3 1/2, and to increase the exposure by 2-3 stops. The print enlargement is a bit over two times. There's no hint of a registration problem.

    After all that, it takes a keen eye to see any difference between the two prints. The masked print has just perceptible better local contrast, but the effect is very subtle. It's certainly not enough to justify the effort of making the mask.

    So my question is, is that it? Am I missing something? Maybe the effect more pronounced with different sorts of subject?

    Any advice would be much appreciated.

  2. #2

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    Re: Unsharp masking

    I'll be very interested in the answers. I hope several people will post masked/not examples! I have only a vague memory of doing this 50 years ago, but do remember that the mask had no detail at all, and was being used for wholeslae burning/dodging, not anything local. But that was a long time ago!

  3. #3

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    Re: Unsharp masking

    From my understanding the mask is very thin in density and has many use's, correct contrast, dodging or burning in and also for improving focus (it does not make the neg sharper but kind of tricks the viewer, that the print is sharp. What were you trying to correct.

  4. #4
    Drew Wiley
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    Re: Unsharp masking

    Learning the ropes of masking can be every bit as much a journey as learning to print well. There are a lot of ways to do it. And it can make a real difference with appropriate images. But it's like any other printing tool, and not a silver bullet.

  5. #5
    Drew Wiley
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    Re: Unsharp masking

    The degree of "unsharpness" can finely tuned by the degree of diffusion to enhace edge effect. But the less unsharp the mask is, the more you'll wish you invested in a punch and register system! I've made thousands of masks for color printing, but substantially less for black and white work.

  6. #6

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    Re: Unsharp masking

    Usually it is a "solution looking for a problem", as there's a # of ways "to skin a cat", with masking being one way to hold back darker local areas on a print...

    Let's see, there's dodging, there's using a flatter paper, there's a better neg exposure + softer development, there's using a diffuse enlarger light source, then there's print alternating dev/water baths, there's cutting overlay masks covering portions of the print (while removing them during exposure), split contrast MG printing, longer scale paper, scanning/manipulation and so on...

    If there was one specific thing to lighten, maybe, but all of the above can usually be avoided by good film exposure and balanced development... Or if someone had too hot highlights, and blasted the print exposure overall to bring them down, then tried to hold back the darks, but this is a little Fred Flintstone way of doing it...

    What all of these are about solving is a neg has slightly a little more range than printing paper, and if the neg contrast is excessive, so too will be the print... Solve that, and the printing is easy...

    Steve K

  7. #7
    Drew Wiley
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    Re: Unsharp masking

    Masking can do all kinds of things because there are so many types of masks. A an elementary level like what is under discussion, the contrast of the original is reduced proportionately in the shadows, then brought back up using a harder paper grade, enhancing microtanality overall, and also increasing edge acutance at the same time. My own pyro negs have a yellow-green proportional stain reining in the highlights; then pan film is exposed using deep blue light to proportionately control the shadow end of the scale. Ortho film is fine; but I use pan because it can be used with color film too. The final mask should look like a soft positive image of the full range of the subject, generally having a Dmax no more than .30 above fbf. That's a good starting point until you're more comfortable with the concept.

  8. #8
    Drew Wiley
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    Re: Unsharp masking

    Forgot to say, don't dev the mask itself in pyro. You want it clear, not stained.

  9. #9
    Drew Wiley
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    Re: Unsharp masking

    Steve, masking can truly do what "none of the above" on your list can. It's more of a highly versatile tool kit than a single tool. But it's obviously more work, and can be overdone if not careful. Things like flashing, reduced film dev, lower paper grades etc just squish microtanality along with the total image contrast. With masking you can have your cake and eat it too. It takes some practice printing masked negs to appreciate when it's a valuable technique, and when it's not.

  10. #10

    Join Date
    Oct 2008
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    Re: Unsharp masking

    Thanks everyone for the comments.

    My objective is to increase the perception of sharpness and local contrast (which presumably go hand in hand).

    Because I had to increase my print exposure by 2-3 stops, I take it that my mask is too dense. An average mask density (not Dmax) of 0.3 would presumably require just one extra stop. But would a thinner mask make more of a difference to the final print? It's hard to imagine.

    The question exercising my mind most is just how much effect should an unsharp mask have? What I've achieved is perceptible but so subtle as to be not worth the effort.

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