Determining whether Coolscan 8000 optics need cleaning?

Discussion in 'Digital Darkroom' started by toni_nikkanen, May 31, 2009.

  1. Sorry for beating a dead horse but what's a definitive and easy way to check if the optics in my scanner are in need of cleaning? Flaring problems have either increased lately or then I've just become more allergic to them and would like to know if I should have it cleaned.
    I tried scanning a holder without film in it with analog gain at minimum and maximum but that wasn't very revealing.
  2. Try posting a crop at 100% of the transition between a dark and light area on a slide. For a more scientific test you would use a slide you successfully scanned in the past.
  3. Ok, here's the full image unprocessed straight from Nikon Scan, black and white point set at 0%:
    Here's a crop of the lower left part:
    To make things more obvious, here's a version of the full frame with 50% Shadows boost in Photoshop's shadow/highlight tool:
    This was a 35mm Velvia scan using the standard film strip holder. What is interesting to note is that whenever I've had strange effects of late, the direction of that effect is always the same: The flaring in these beer pint pics is vertical. A month ago I took a landscape 35mm pic of a lighthouse; the lighthouse top flared all the way up towards the sky. At around the same time I took a 6x7 picture of a bird watching tower, again in landscape orientation and the tower had some kind of annoying vertical bar above it. Never did I see anything wrong in the film itself and indeed I tried rubbing it with a microfiber cloth etc. to no avail.
    I'm already mentally committed to at least have the unit cleaned totally. I'll see what to do after that's through, I'm certainly going to make comparison scans.
  4. Tony,
    Carl Pearson of Pearson imaging wrote an aritcle about cleaning the mirror in Nikon 4000 or 5000 scanners. I believe in the end he wrote that the flare issue was not reduced much after cleaning the mirror.
    The flare problem occurs even with a new scanner.
    Your photo examples are a good example of why you should only boost shadow detail when there's something in the shadows that needs to be seen.
  5. Thanks, on that page you linked there was this very nice example:
    (Of course I boosted the shadow details here only for illustration purposes since there was nothing to be seen in the shadows, but flare of this kind indeed prevents me from doing that even when there is something to be seen.)
  6. I wouldn't use shadows and highlights as it creates halos. I'd just go into levels and move the midpoint slider over to brighten the shadows.
    Based on this you might benefit from cleaning.
    With my LS5000 I found that the way to maintain color accuracy in shadows (multisampling would take care of noise but doesn't help with color accuracy) is to scan at two exposures and then blend together (I use Photomatix). Big shadow detail and color improvements over other methods.
    When I get a chance I'll upload my tests to a website.
  7. Dust bunnies in the optics will leave faint streaks in the fore-aft direction. These can be revealed if you scan a piece of clear (or uniformly fogged) film. The auto-exposure mechanism will exaggerate minute differences in contrast.
    I have seen flare when scanning transparencies, but it's not clear if it occurs in the original slide or just the scanner. Only a very thin strip of film is illuminated at any one time and the sensor array is also very thin. If flare occurs, it is only two-dimensional.
  8. What do these last two examples illustrate? Before and after?
  9. Yes, before and after. Here's one more, again before and after.Other examples that don't have so much contrast still do look better but you have to be as picky about contrast as me (and have the original slide on a light table next to you so you actually know what you're missing :)
  10. That's a pretty significant difference!

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