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Thread: Weird patterns on scans of long exposures

  1. #1

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    Weird patterns on scans of long exposures

    Hi folks. I've started trying 5 sec+ exposures on TMX 100 4x5 and I'm getting some weird results when I scan them. On some I'm seeing a vertical wave pattern (when I'd expect to see only a horizontal one due to cloud and water movement) and on others I'm seeing a grid pattern. Easier to show than tell – here are two examples:

    http://www.stepwise.ca/images/Grid_pattern.jpg

    http://www.stepwise.ca/images/Vertical_pattern.jpg

    Please ignore the Newton rings – I'm scanning with a cheap Microtek flatbed that I use just for proofing.

    Scans of shorter exposures look fine.

    I can't figure this one out. Any ideas?

    Thanks!
    Mark McCarvill
    http://markmccarvill.com

    The miracles of creative art lie not in particular materials and methods, but in the basic concepts involved. – Ansel Adams

  2. #2

    Weird patterns on scans of long exposures

    I'm scanning with a cheap Microtek flatbed

    That could be your problem right there: only expensive scanners can tell how long the exposure was and adjust accordingly.

    Seriously, there's no way length of exposure could have anything to do with your problem unless it's caused you to blow out your exposure. I know my scanner has problems with high density area of negatives.

  3. #3
    Ted Harris's Avatar
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    Weird patterns on scans of long exposures

    Thefirst one looks to me like it could be caused by dirt in the scanner control path......the skinny area either above or below the main scan area. Which model Microtek?

  4. #4

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    Weird patterns on scans of long exposures

    Michael, I will scan the negative on a good scanner and see if the pattern persists. Still, I'm curious to know what’s causing this grid pattern.

    Ted, it’s a Microtek Scanmaker 5900.

    What about the vertical waves (they look sort of like flames) ... are they normal? I thought the cloud pattern should be more horizontal. Or should I just claim this was purely intentional?!
    Mark McCarvill
    http://markmccarvill.com

    The miracles of creative art lie not in particular materials and methods, but in the basic concepts involved. – Ansel Adams

  5. #5
    Ted Harris's Avatar
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    Weird patterns on scans of long exposures

    Mark,

    Hard to make any judgement at al without seeing another scan from a much better scanner. Consider that the Microtek i900,Epson 24503200/4870/4990 or Canon are usually considered the 'entry level' or 'consumer' scanners for scanning LF and you are using a scanner that sold new for less than 100 (25% of those mentioned) and goes for 20-30 on the used market. AIt likely just isn't up to the task but send us another scan before we pass any real judgement.

  6. #6

    Weird patterns on scans of long exposures

    why not make a "real" print at a "real" lab, i find those things indispesible references, even if i have already scanned or am going to scan, for one copy it shouldn't be that expensive and it'll help you work out your exposures.

    ...

  7. #7

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    Weird patterns on scans of long exposures

    It has nothing to do with the negative.
    I have dealt with those patterns for sometime and i decided to send important scans to a good lab.
    From what i understand , the grid patterns are a fairly common phenomena .
    Almost all scans have them, the problems arises if they are visible at 200% zoom-in or less.
    I can see grids in drum scans done from A&I here in LA, a very reputable lab, at about 340%, and are not visible whatsoever in an hard print.
    Struan Grey, a member of this forum , explained me once that the patterns are caused by electrical interference
    by sources in proximity of the scanner .
    One way to reduce this problem is scanning to a multiple of the initial scan, don't ask me way.
    Good luck.

  8. #8

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    Weird patterns on scans of long exposures

    Thanks for the feedback, folks. I will rescan on a good scanner and post the results for the curious.

    Domenico – interesting point about grid lines being in most scans. Perhaps that’s the answer, and the reason the lines only appear in these long exposures (and only in the sky and water portions of these images) – because they have large areas which are the smooth and show little contrast, thus providing an ideal background for the lines to show through.
    Mark McCarvill
    http://markmccarvill.com

    The miracles of creative art lie not in particular materials and methods, but in the basic concepts involved. – Ansel Adams

  9. #9

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    Weird patterns on scans of long exposures

    Mark, the second looks to be exibiting the results of lack of agitation during processing. That mottled appearance is pretty typical from lack of agitation or exhausted chemistry.

  10. #10

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    Weird patterns on scans of long exposures

    Thanks, Ed. I called my lab and they say they do test strips every morning but maybe my film was processed in the afternoon when the chemistry was getting exhausted. I will try a one-shot chemistry lab next time.
    Mark McCarvill
    http://markmccarvill.com

    The miracles of creative art lie not in particular materials and methods, but in the basic concepts involved. – Ansel Adams

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