Anyone digitising slides with a 20+ mp DSLR?

Discussion in 'Digital Darkroom' started by zoltan_arva_toth, Mar 4, 2010.

  1. Has anyone tried digitising slides using a 20+ megapixel DSLR camera, a macro lens and a slide copying attachment? What have your results been like with slow films like Kodachrome 64 or Velvia?
     
  2. Zoltan, I do this often with Ektachrome film, using a XTi and 18-55 mm lens. Not a 20+ meg but....They come out OK, grain is intensified but can be delt with in PS with noise filter. I use plastic mounts that can be used over again and again. I shoot in RAW. The biggest problem I have is the slide is not perfectly straight and you get a black area around the film (which is the inside of the duplicator) This can be cropped out in PS. Most of the duplicator are 52-55 mm in diameter, my lens is a 58m diameter. So right there I have an issue with a black area around the film. I have tried a 70-300 mm but it would not focus that close. Hope this helps. ed
     
  3. Zoltan, I digitize almost all of my slides by the method you mention. These days, I am using a d700, a 105/2.8 VR macro lens, and a slide copying attachment, but in the past, I have used lesser equipment with entirely adequate results. For the light source, I always use an SB600 off-camera, wireless TTL, close to, and aimed right into the back of the slide copying diffuser. This amount of diffusion, much like a diffuser head on an enlarger, seems to eliminate any grain enhancement problems even with films notorious for such problems such as K25.
    I find that this is, by far, the fastest method to digitize large numbers of slides. Only rarely do I ever have to resort to actually scanning a slide anymore. The example attached below is a Kodachrome 25 slide from about 1970, digitized using the method described above, except I used a d200 instead of a d700. Both of these bodies are well less than the 21 Mpixel resolution you stated and perform admirably.
    Thusfar, I have digitized several thousand K25 slides this way. To reduce post processing tasks, I prefer to use my d700 over my d200 because I can use the Active-D lighting feature on the d700 to help capture the large dynamic range of Kodachromes.
    HTH,
    Tom M.
    00VutE-225961584.jpg
     
  4. mpd

    mpd

    Tom,
    What do you use for a slide copying attachment?
     
  5. M. Patrick D - I am using a very old version of one of these: http://www.adorama.com/NKES1.html?searchinfo=slide+copy plus some old extension tubes to get the correct spacing (ie, magnification). This type of slide copying adapter contains no lenses. Instead, it relies entirely on the close-focusing capabilities of your macro lens.
    Other types of slide copiers are available which do contain a close-up lens (usually a +10 diopter), and can be used with a normal, non-macro lens (eg, http://specialtyphotographic.stores.yahoo.net/slcounpro.html, http://www.amazon.com/Opteka-Slide-Copier-Nikon-D70s/dp/B000FA76JS, etc. ). Other models are available which are designed to be mounted directly to your camera body in place of a lens.
    I have never heard a good report about the image quality from either of these latter two designs. The primary complaint is that the optics in them are far inferior to that of a normal macro lens. Another complaint is that many (most?) slide copiers of the latter two designs have a fixed, very small (eg, f/22) aperture and rely on depth of field to remove the need for focusing. This creates two problems: (a) loss of resolution due to diffraction, and (b) it's virtually impossible to see anything through your viewfinder, so, for example, you can't tell if your slide was inserted properly and is centered in the frame and at the correct angle.
    There is lots of material available on the web discussing the use of slide copying adapters. One of the best web sites is http://www.scantips.com/es-1.html.
    In the interest of full disclosure, there are problems with this method. First and foremost, the resolution is not quite as good as you will get from a good quality, dedicated slide scanner. However, using my very good but costly Nikon 105/2.8 VR macro, I can resolve individual grain clumps, so the resolution isn't bad. In return for the slightly lesser resolution, you get much less sensitivity to grain (because of diffuse lighting with the slide copying adapter), and an absolutely HUGE increase in speed. When working with my wife or daughter (who pulls slides from the box, dusts them and returns them to the storage box), I can re-photograph two or three slides per minute, each labeled consistently with a unique identifier! Compare that to the throughput of a slide scanner. ;-)
    Other problems that are sometimes stated about rephotographing slides include:
    • a) color casts - Set your WB once for your particular setup, and this problem completely disappears;
    • b) build-up of contrast - This was a problem in the days of film. Now, just set your in-camera contrast lower;
    • c) difficulty telling if the slide has been centered and oriented correctly - This is only a problem with the cheap, f/22 and f/32 fixed aperture slide copying adapters which give a very dim image in the viewfinder;
    • d) difficulty in exact positioning of the slide, even if you can see it through the viewfinder - If you want your image to go right up to the edge of the cardboard mount of the slide, yes, physically bumping the slide by fractions of a mm is more difficult than moving a cropping box in Photoshop. I have resolution to spare with my setup, so I simply use a slightly longer extension (distance from the front of the macro lens to the slide). This allows the edges of the cardboard mount to be seen in each image, and then, if exact cropping is sufficiently important, I can precisely crop and micro adjust the orientation in PS.
    • e) Difficulty in retaining the full dynamic range of a good Kodachrome slide. This can be a serious consideration, but can be dealt with. First, recognize that probably only a small fraction of your slides needs to maintain all this range. For most people, most of their slides are being digitized for memory / archival purposes, not for fine art or scientific purposes, and a huge dynamic range isn't needed for these. For those slides whose full dynamic range you want to retain, you can either turn on "Active-D" lighting in Nikon equipment or its equivalent from other mfgrs. If that doesn't provide enough of an improvement, do a three shot bracket of each slide (ie, +2, 0, and -2 stops) and combine the three exposures with HDR software. This works wonderfully in bringing new life back into old slides, but is time-intensive. For these slides, you may want to consider a good, high-end scan.
    Finally, it's my experience that over the years, expectations have risen significantly w.r.t. image quality, so that even if re-photographing a slide provides a virtually perfect copy of that slide, the image on the slide may have problems such as poor lighting, color casts, soft focus, excessive or low contrast, poor framing, etc. Many of these flaws can be improved in PS, but, (a) doing so adds enormously to the time per slide, and (b) these flaws will be present whether you use a slide copying adapter or do a high rez scan of the slide.
    HTH,
    Tom M.
     
  6. mpd

    mpd

    Tom,
    I have one of those cheap adapters from China. It was a bit cumbersome. Thanks for the great advice. pat
     
  7. If you mean cumbersome to handle, I have QR plates on all my bodies, so I just mount my camera (with macro lens and slide copying adapter attached) to a big, heavy studio tripod, and the awkwardness of hand-holding a long extension to the front of the lens goes away. I just sit my SB600 flash on a bookshelf pointed back at the front of the lens, so dealing with it is no big deal.
    Also, it's important to use a macro lens in which the front of the lens and filter threads don't rotate when focusing. That certainly could make focusing and framing awkward.
    The only aspect of the process that I have ever felt to be a bit awkward was that on one of my slide copying adapters, the length adjustment tube was a bit loose. A few inches of low tack, blue painter's masking tape fixed that.
    While this method isn't exactly a self-contained box that sits on your desk, so you have to assemble the pieces each time you want to copy some slides, if you are digitizing thousands of slides, the increase in speed over any scanner that I've tried is so enormous that I'll put up with the minor bit of assembly and slight loss of IQ compared to a desktop scanner.
    Cheers,
    Tom M.
    PS - Speaking about IQ, the example image that I posted earlier was printed on 16x20, matted as shown, and hung in a show for a month. It was more than adequately sharp.
     

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