Masking film emulsion up or down when creating unsharp masks?

Discussion in 'Enlarging' started by Seabird, Dec 29, 2010.

  1. Seabird

    Seabird Member

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    I'm just starting to explore the world of mask-making for B&W printing purposes. My questions pertain to correct technique for creating unsharp masks.

    Fig.1 on p.257 of Ralph Lambrecht's most excellent "Way Beyond Monochrome" (Ed.2) indicates that when creating the mask (i.e. not printing) both negative and masking film are placed in a "sandwich" with both films emulsion up.

    But:

    Fig.2 in Mark Jilg and Dennis McNutt's article "Three Contrast Reduction Masks" indicates that when creating the mask both masking film and negative are placed in the "sandwich" emulsion down. Similarly, Howard Bond's article in the Jan/Feb '96 edition of "Photo Techniques" indicates emulsion down.

    In short: why the difference and does it matter?

    I appreciate that if the masking film is a thin base film (e.g. ortho-litho) used emulsion down without a spacer then the degree of "unsharpness" will be severely restricted on account of the thin base of the masking film. By contrast, placing both emulsion up means that the degree of "unsharpness" is always at least that due to the thickness of the negative base.

    Does this explain why Lambrecht (who is chiefly interested in sharpness effects) recommends emulsion up and Jilg/McNutt (who are more concerned with contrast reduction than sharpness) recommend emulsion down?

    Any other pros and cons to either approach that I'm missing? Comments appreciated and thanks in advance

    Cheers

    Carey Bird
    http://members.iinet.net.au/~cbird/index.html
     
  2. MarkL

    MarkL Subscriber

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    Yes you're correct about the differences in film orientation. Jilg and McNutt wanted to reduce contrast with no edge effects (contrast reduction mask). An unsharp mask for increasing apparent sharpness via edge effects is achieved by a bit more space between the emulsions, which makes the mask image very slightly larger.
     
  3. Seabird

    Seabird Member

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  4. Hikari

    Hikari Member

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    In mask making, emulsions should always be facing. Both when making and when printing. An unsharp mask is made using a diffuser, which causes the unsharpness, but needs to be registered to the original neg. Registration is best when no space exists between the emulsions.
     
  5. Seabird

    Seabird Member

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    Hi Hikari,

    Thanks for your response.

    Sorry but I dont understand. Why should the emulsions always be facing? (This advice is contary to all the sources cited in my original post.)

    Best Regards

    Carey Bird
    http://members.iinet.net.au/~cbird/index.html
     
  6. Photo Engineer

    Photo Engineer Subscriber

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    In the Kodak Dataguide "Color Separation and Masking" they give only one method of masking as follows:

    Light Source ------> /Original Emulsion/Base/// Diffusion Sheet .003" max optional ////Emulsion of print material/Base/

    The optional iffusion sheet is recommended for unsharp masks, but is omitted for normal masks. This is from page 39 of the manual. It goes on to show that the masks are used emulsion to base with the original closest to the lens.

    PE
     
  7. Seabird

    Seabird Member

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    Hi PE,

    Thanks for replying and sharing that.

    Its interesting that Lambrecht and the Kodak guide you refer to advocate the same orientation, while Jilg & McNutt advocate the alternative - and Howard Bond has PROVEN (to my eyes) that the alternative works beautifuly. :smile: I conclude that perhaps it doesn't matter, but will have to try both and see for myself.

    Thanks again

    Carey Bird
    http://members.iinet.net.au/~cbird/index.html
     
  8. Photo Engineer

    Photo Engineer Subscriber

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    Carey;

    It is sometimes difficult to spot changes unless you see direct side-by-side comparisons. If someone shows you a good print from a given masking method, all well and good if you are satisfied, but for real proof you need to be shown 2 prints comparing both methods out there before you can have true "proof"!

    But, use what works!

    PE
     
  9. rmolson

    rmolson Member

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    masking film

    In reference to the Kodak book on color separation.The film that they normally recommended was a film designed for masking and as memory serves me used base to base.It was a very low contrast film making control of contrast in development easier And of course it was panchromatic.
     
  10. rmolson

    rmolson Member

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    PS

    Opps that was emulsion of the masking film to the base of the original
     
  11. Photo Engineer

    Photo Engineer Subscriber

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    That is how I said it was used.

    Kodak did make Pan Masking Film, but any film could be used if the job was done properly.

    PE
     
  12. Dennis McNutt

    Dennis McNutt Member

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    The orientation of the films used in masking depends on what one is intending.

    Sometimes one desires more than one result. For example, in making a CRM by exposing the masking film through the base one can enjoy both sharpening and contrast reduction effects; a degree of sharpening is caused by the distance between the emulsions of the original negative and the emulsion of the masking film. A thicker base on a masking film gives more separation and more sharpening than a thinner base. Using a diffuser film when exposing the negative/masking film sandwich will also increase sharpening.

    So the comment I read in the discussion above is incorrect: "Jilg and McNutt wanted to reduce contrast with no edge effects." In the original articles on our research we discussed both.

    In my work I have used about every combination of orientations in exposing and printing with masks to achieve different purposes--in exposing a mask I sometimes put the masking film below the negative--that is with both emulsions down--and make the exposure through the masking film base (I know this sound counter-intuitive but there is a logic to it.) To make other masks I use an emulsion-to-emulsion orientation.

    So the notion that masks must always be exposed in a specific orientation does not conform to my experience.

    The variety of masks and the ways of making them are numerous, and therefore somewhat complex. The brief discussions of masking in this forum often over-simplify and occasionally mis-inform.

    To my limited knowledge the best printed resource on masking is found in Lynn Radeka's Masking Kit. The kit includes the original three articles on CRMs, SCIMS, and HLMs that Mark Jilg and I wrote in 1989. It also includes additional articles on other masks written by Lynn Radeka.

    To learn more about the Radeka Masking Kit, just do a quick Google search.

    I love masking and can't imagine living without the unique powerful controls its give me when printing. It seems that learning masking by using only online resources would be challenging, to say the least.