Neg or Pos for scanning?

Discussion in 'Medium Format' started by dae, May 24, 2010.

  1. More learner MF questions. From the point of view of getting the best print , is there a difference in quality between Negative & Slide film scans?
    Many thanks.
     
  2. stp

    stp

    Yes, the negative film will have a wider tonal range, while the positive film will generally have more saturated colors. In areas of high contrast, folks generally recommend negative film. In areas with a more restricted range of light and with great colors, folks generally recommend positive film. If you are scanning, the issue of color saturation is easier to remedy than tonal range when doing digital processing. I find that positive film is a lot easier to work with; I haven't yet found a relatively inexpensive way to get the equivalent of a contact sheet for negative film so that I can determine which frames I may want to keep and which I may want to simply discard (the alternative is to scan everything, and that's a lot of time and work). I hope others will jump in with some opinions that will be useful to both of us.
     
  3. I'm kinda in the other camp as Stephen, but probably have less experience to speak of.

    To quote a good explanation, negative film compresses dynamic range into the film, and slide film expands it (or at least holds it constant).
    Thus, when scanning negatives, you have to expand that tonality back out, because the scanner pulls a narrow histogram out of the negative. This leaves an image with a bit of a flatter look that takes a bit more fussing at the ends to get right. Likewise, with the color, getting rid of the orange base seems to muddy the colors a bit.

    Conversely, when I scan slides, the histogram is about 2-3x wider on my scanner, and the color is "right there". It seems to be MUCH less work to get that info into the computer.

    Of course, you can't see a negative with your naked eye, so it's hard to do a fair comparison. ;-)
    I can see the issue with contact sheets, but I stopped getting those when I went full mail order with Dwayne's. I shoot only a few rolls a month, so scanning them all is doable.
    So, assuming I can get the same image onto either film (exposure headroom, etc), I find slides are easier to get the info OUT of.

    But most of my film is negs, because it's cheaper to buy and process. :)
     
  4. I too prefer scanning positive film vs. neg film. I prefer the look of positives, and I prefer the truer color. Maybe with a lot of work a neg scan can look good, but I'm a slide guy all the way.
     
  5. I usually get better results out of scanning positives on my flatbed scanner -- whether that's due to the inherent scanability of positives versus negatives or my own inability to scan negatives well remains to be seen.
    The only reason I dislike shooting slides is because the scan just never comes close to how good those slides look on my lightbox!
     
  6. For the reasons that Gregory explained so well above, negative scans often appear to be a bit noisier than positive scans. The input tones are much closer together in density on a negative than on a positive, so any scanner noise (any random error in measuring those tones) gets amplified when you stretch the histogram out to make the picture look normal.
    The other thing is that bright regions in the image (sky, clouds, snow etc.) are dark and dense on the negative, which means less light throughput in the scanner, which means more noise. Skies which are noisier than the landscape below just look wrong, since it's an inversion of our perceptions - we are used to noise being associated with darker regions. This is usually only a problem with overexposed frames, or dense B&W negatives. Good scanners and good scanning software (e.g. Vuescan) also allow noise reducing techniques like multi-sampling.
    I usually find it easier to scan slides, with the exception of greatly underexposed ones (like some night shots or short astrophotos), which show more faint detail on the lightbox than a scan can pull out without gross noise. The DMAX rating of the scanner needs to be high, in order for it to dig down to the very darkest shadow detail, just above the slide film rebate density; and again those multi-sampling etc. tricks can really help as well.
     
  7. if you have a pro level scanner go with positive,
    if not, go with negative, positive is to dense in dark areas.
    Regards
    martin
     
  8. david_henderson

    david_henderson www.photography001.com

    Its not just a question of which scans best.
    Slide film is much more difficult to expose correctly, and has more of a learning curve. You are more likely to produce a usable negative than a usable slide when you're learning. Once you get to the point where your control over exposure is good enough for slides, then thats what I'd prefer to scan- not least because you can see what the image looks like to provide a target for colour, brightness etc, and indeed to choose which originals you want to scan/print. Most people don't read negs very well till they have a lot of experience.
     
  9. Even when you know how to expose slide film perfect, it still holds less information than negative film.
    Not that the amount of information is the begin all, end all of photography. But the small dynamic range slide film can capture is almost always bothersome, it just doesn't look good.
    So why bother, i'd say.
     
  10. Thanks for all the useful information. I think the best thing I can do is get off the Internet and go see results first hand.
    Get the slides scanned, get the negs scanned. And conclude what's going to be best for me. These forums always
    end up repetitive. :)
     

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