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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
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    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 :
    http://www.ilford.com/html/us_english/pdf/303e.pdf


    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.
    http://www-unix.oit.umass.edu/~jpalma/scanning_bw.html

  3. #3

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    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

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    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
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    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

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    Paper Resolution

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


    http://www.greenspun.com/bboard/q-and-a-fetch-msg.tcl?msg_id=004TDI

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