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  1. #21

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    I GUESS SO!

    Quote Originally Posted by rob champagne View Post
    Just to confirm, where you say for example, Fuji Across 200 lines per millimeter, thats means 200 line pairs per millimeter. Yes?
    Further research is up to you.

  2. #22

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    Quote Originally Posted by Paul Verizzo View Post
    Further research is up to you.

    I'll take that as a don't know then.

  3. #23
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    On Manufacturer’s Documentation and The Photographic System

    Kodak has a tradition of publishing accurate and copious data to enable a photographer to get the most from EKC materials, and in the process, learn a great deal about photography.

    Ilford's documentation has never been directly comparable to Kodak.

    Fuji does everything possible to look better than Kodak.

    ...................................

    Film classes give similar performance.
    If you can make a picture with Tri X, you can make it with HP5, or Neopan 400.

    There are differences in curve shape, and how the films render color,
    but granularity and resolution are essentially the same.

    In this regard,

    TMY = Delta 400

    TMX = Delta 100 = ACROS.

    If you see a difference between films’ grain,
    review your processing; you probably induced the difference.

    Remember that Photography is a System.
    Using a perfect camera, a perfect lens at its perfect aperture,
    and printing perfectly through your perfect enlarger,
    increasing the resolution of your film from 100 to 200 lines/mm gives a net gain, on the PRINT, of 17% ! ( More or less).

    For example, the differences between using TMY instead of ACROS
    come down to an imperceptible resolution loss,
    a small increase in granularity,
    and a significant reduction in potential image blur because of a shorter exposure.


    Without the systematic context, no true comparisons can be made.
    Last edited by df cardwell; 07-24-2008 at 10:18 AM. Click to view previous post history.

  4. #24

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    Quote Originally Posted by rob champagne View Post
    Just to confirm, where you say for example, Fuji Across 200 lines per millimeter, thats means 200 line pairs per millimeter. Yes?
    This can be very confusing. One of the issues is that there are at least two charts commonly used to test resolution, the PIMA/ISO resolution target, and the USAF 1951 target. The first expresses resolution in line pairs per millimeter (lp/mm, or LPPM), the second in lines per millimeter (l/mm, or LMM). Just understand that numerically lines per millimeter (L/mm) is double line pairs per millimeter (LP/mm). 100 lines per millimeter (l/mm) is 50 line pairs per millimeter (lp/mm).

    Kodak uses the term "lines per millimeter" when discussing resolution.


    Sandy King

  5. #25

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    Quote Originally Posted by sanking View Post
    This can be very confusing. One of the issues is that there are at least two charts commonly used to test resolution, the PIMA/ISO resolution target, and the USAF 1951 target. The first expresses resolution in line pairs per millimeter (lp/mm, or LPPM), the second in lines per millimeter (l/mm, or LMM). Just understand that numerically lines per millimeter (L/mm) is double line pairs per millimeter (LP/mm). 100 lines per millimeter (l/mm) is 50 line pairs per millimeter (lp/mm).

    Kodak uses the term "lines per millimeter" when discussing resolution.


    Sandy King
    Exactly, so when Fuji says Acros is 200 l/mm it means 100 line pairs per millimeter.( I think )

    Luminous landscape has some info on this but I don't know if its correct.

    http://www.luminous-landscape.com/tu...ding-mtf.shtml

  6. #26

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    From this chart, T-Max 100 should reach about 200 cycles/mm (IMO that is line-pairs/mm) at low contrast:
    http://kodak.com/global/en/professio...002_0542ac.gif

  7. #27
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    Actually, sharpness should be expressed as MTF, or modulation transfer function. This plot, given on the Kodak web site for many products shows how a product responds at a given frequency of lines. More modern methods were under development at Kodak. One of the people in the forefront of this was Mike Kriss who has produced mathematical representations of a film's Information Capacity. This is published in the SPSE book "Color: Theory and Imaging Systems". It is a very long and math heavy exposition that I will leave to Kirk Keyes to explain.

    I recently sent Kirk a copy of the article.

    PE

  8. #28

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    Recently - that was two years ago... Since the birth of my daughter, it doesn't take much math to make my head hurt... I still have not finished. But it's right here on my desk for when I'm mentally capable of finishing it!

  9. #29
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    I have both the Kodak charts and the USAF targets here. I have both in negative and positive format. I may get around to posting images of them someday. I have used the Kodak charts in testing the sharpness of my hand coated papers and have posted some of the results here on APUG.

    Kirk has seen my USAF targets.

    PE

  10. #30

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    I played with the USAF targets for a while. It takes a little work to balance the exposure to get the positive and negative chart results to be close. And it takes a little work when using an enlarger to get sharp results - a point source would be better than an enlarger. I racked mine all the way up and used a small aperature to get better results.

    Trying to be fair when reading the results, I was able to get Fuji Acros to read about 160 lpmm.

    Kirk

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