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Thread: Paper Resolution

  1. #1

    Paper Resolution

    I have been making many resolution tests on my camera lenses, with resolutions up to 80 lp/mm using the RIT test patterns. When I try to enlarge these patterns in my rigid Durst 138s at 2X, 3X, 4X & 6X with both a 100mm Schneider Componon or a 210mm Componon, all I have for resolution on my Ilford Multigrade V paper is a 10 to 12 lp/mm.
    Has anyone measured paper resolution?

  2. #2

    Join Date
    Jan 2002
    Besanšon, France

    Paper Resolution

    Patrick. You should give us some details on how you measure your final resolution on print. Finding only 10-12 lp/mm does not seem to match what I know from actual resolution of papers. The limiting resolution factor is probably elsewhere in your experiments.

    20 years ago I tested traditional B&W paper by contact printing a USAF test target (fabricated on a chromium glass photomask) on a piece of photographic paper. I found a resolution above 50 lp/mm. This was traditional glossy baryt paper.

    Ilfochrome paper is credited 63 lp/mm according to this official datasheet :

    Taking into account that the first light- sensitive layer in an Ilfochrome is certainley silver halide, I cannot imagine how the resolution of a glossy silver halide B&W paper could be only 10 lp/mm. Even a B&W Polaro´d print is credited something between 13 and 25 lp/mm.

  3. #3

    Join Date
    Jul 2004
    Tucson, Arizona

    Paper Resolution

    Regarding lp/mm, the "l" is lines and the "mm" is millimeters, but don't both the "p" and the "/" mean "per"? (Hence, "lp/mm" reads "lines per per millimeters"?) Inconsequential, but little things sometimes bug me...

    Anyways, I'd check the resolution coming through your enlarger lens with a good grain focuser just to see whether all those lines are reaching the paper. (And don't shake the enlarger.)
    "I love my Verito lens, but I always have to sharpen everything in Photoshop..."

  4. #4

    Paper Resolution

    Mark -

    Actually, lp/mm stands for "line pairs per mm".

  5. #5

    Join Date
    Jan 2002
    Besanšon, France

    Paper Resolution

    One line pair is one cycle, i.e. one bar plus one space to make one period of a grid.

    In the above messages, please replace 'lp/mm' by : 'cycles per mm' and there will be no ambiguity.

    In the photomask I used, when the bar is 5 microns wide and the space 5 microns wide, the period is 10 microns, the tested resolution is therefore 100 cycles per millimetres. I remember that I could read patterns with 10 microns bars plus 10 microns space, period 20 microns for a resolution of 50 cycles per millimetre or 50 lp/mm. This figure of 50 cycles/mm as well as the 63 cycles/mm for Ilfochrome exceeds by far the resolution of the human eye for a print examined at a 10" (250 mm) distance, where 7 cycles / mm is considered the resolution limit in visual observation.

  6. #6

    Paper Resolution

    Back in 2002, I think feb. Ctein did an article in Photo Techniques Magazine titled: "Is your print paper sharp enough".

    The short answer was: yes.

  7. #7

    Paper Resolution

    could depend on the enlarger light. A condenser for example will give more in the way of sharpness than say the diffused cold cathode. A point source light is best if it's sharpness you want.

  8. #8
    Abuser of God's Sunlight
    Join Date
    Aug 2004
    brooklyn, nyc

    Paper Resolution

    My experience suggests that with enlarging, fiber based paper does in fact limit resolution. This is based on the simple observation that the finest detail clearly defined through a focusing loupe (like a peak/micromega critical focuser) will not be visible at any magnification on the final print. Yes, the observations are made with the focuser sitting on a piece of the same paper stock, and no, that degree of change in focal plane would not be enough to make the difference I'm seeing.

    I don't believe that tests made using a contact printed test target under pressure are applicable. A projection printed neg is going to have lower contrast (lower mtf) detail, and the surface of the paper will not be pressed flat. A test like this shows maximum resolveable detail under perfect (and therefore completely unrealistic) conditions.

    That being said, I think the limits will only be aparent when looking at a print with a loupe. The paper doesn't seem to soften contrast at the moderately high resolutions (5lp/mm or so) that our eyes use most to determine sharpness. My own very informal tests have shown glossy paper to resolve at least 12lp/mm. This included wires on a window screen that were completely invisible to the naked eye at any distance but clearly defined when seen with a 4x loupe.

  9. #9

    Paper Resolution

    Emanuel -

    Thanks for sharing your results. Could you clarify on a few points?

    > I tested traditional B&W paper by contact printing a USAF test target <

    What was your contact printing setup? What size paper did you use? How did you hold the test target in contact with the paper?

    > I found a resolution above 50 lp/mm. <

    How did you examine the print to assess resolution?

    > I remember that I could read patterns with 10 microns bars plus 10 microns space <

    What standard did you use to judge that the test pattern at a given frequency had been unambiguously rendered in the print?

  10. #10

    Join Date
    Nov 1999
    San Clemente, California

    Paper Resolution

    Don't know why it didn't make the transition to, but see what I said on the subject in this thread:

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