Some Lessons Learned for Film Scans

I’m going to put off the post with old photo examples.

picture of Kodak slide projector and a stack of carousel traysI’ve completed going through all the prints. I’ve now also done about 900 film scans, mostly 35mm Kodachrome slides, with some Ektachrome as well. Some were stored in boxes, but most came out of Kodak Carousels with 140 slides each.

Workflow and setup

  • I set up my old Kodak slide projector and a screen to do a quick preview before taking the slides out of the carousels. This turned out to be a just a ‘nice to have’ and you could skip it as long as you’ve got the sorter below.
  • I also set up my old slide viewer/sorter. As I took the slides out of the carousels I put them on the sorter to find the ones to be scanned and group them into sets of four (that’s what the adapter holds). Without the sorter, the job would be much harder—if you don’t have one and are going to be scanning more than just a few dozen slides I’d recommend getting one.
  • Getting slides out of boxes or the carousels is a lot easier and faster than dealing with albums. But the extra care with handling and time for cleaning ate up some of the time savings.
  • I decided to not put them back in the carousels, instead I bought some more slide files and put them in those, preserving the order from the carousels.
  • A soft photo brush and the compressed air spray are crucial here—you really don’t want to have to turn the infrared cleaning  filter on if you don’t have to and a careful cleaning helped a lot.
  • I found it better to ignore how the picture was taken and loaded the holder with the slides all oriented the same way (portrait or landscape). The software is supposed to be able to detect the orientation and rotate the crop but it often got it wrong—I think it got fooled by slides with dark areas along the edges. You can also explicitly tell it which frame (slide) to rotate and how but it was quicker to do that afterward.

photo of a set of slides on the sorterFilm scanning is all about trade offs

  • The big trade off is quality of the scan vs. the time it takes. I found I had to compromise to get it done this decade (slight exaggeration).
  • 2400 pixels per inch (ppi) is enough to get images roughly like a good digital camera in the 8-12Mpixel range. That’s plenty for viewing on a monitor or making prints up to at least 8×12, but more would be very desirable.
  • Most sources say >20Mpixels are needed to extract everything from a 35mm slide or negative, and that’s at least 4000ppi. The scanner can do up to 9600ppi, but with the quantity facing me, the time required for 4800ppi scans is simply impractical for 100% use.
  • Multi-pass scanning for higher dynamic range can make a difference, especially for slightly underexposed slides, but it more than doubles the scan time.
  • Infrared cleaning (Digital ICE or similar) for dust and scratch removal works, but it adds multi-pass scan time and processing time—at least double the basic time.

I settled on 3000-3600ppi scans, single pass, no ICE, stored as JPG files as my ‘normal’ setup. That gets me images of at least 10Mpixel size with JPG file sizes in the 5-6MB ranges. When saved as a TIFF they’re 2-3 times that for file size.

  • Exceptionally nice images (one in a hundred maybe) got the full treatment: 4800ppi (more if I cropped during the scan), infrared scan if needed, dynamic range pass if needed, dual output to TIFF and JPG.
  • Images with big areas of no detail and no texture (usually that was sky) got ICE turned on in the basic scan. No matter how well I cleaned things the dust specks were always lurking.
  • Dark images that I really wanted to get the most from got the 2-pass, dynamic range function turned on and the output saved as a TIFF for future edits.

At a guess, I’d say doing the slides took me 2-3 times as long as the prints. Time invested in cleaning them and scanning time was much longer and there’s more fuss selecting the ones I wanted. For me, it’s worth it–at least for these family shots. More on that below.

Kodachrome: the good news, and the bad news

Picture of a Kodachrome film box.On the one hand, the slides turned out to be in superb condition and virtually no fading showed up. For the Kodachrome that should be the case, they’re famous for longevity and even my 40-year old ones are still young.  A very few showed a bit of color shift that was corrected easily and it may have been white balance errors and not fading. Kodachrome (and slide film in general) is also famous for the fact that exposure latitude is almost nil and underexposed or overexposed is hard to recover from. Mine were rarely over, but often under and some by as much as a stop—getting something ranged from difficult to impossible. I settled on leaving it somewhat dark to preserve the highlights and saved them as a TIFF to work on them in PhotoShop later. But when the exposure was good, they were gorgeous seen with the projector and in the scans.

All is not perfect.
Nearly every scan I looked at closely was a bit softer than I thought it should be. They look fine until expanded to full (pixel-for-pixel) size. I can tell that some of the softness is camera shake, subject motion or a lack of precision in the focus in the first place. However, some of it seems to be in the scan, but not the slide. It is possible that the scanner isn’t focusing correctly, but that seems unlikely since prints looked sharp, as did the b&w negatives. I think it’s probably coming from curvature in the mounted slide film. That’s normal and the Kodak projector has special lens designed to correct for that curvature, but the scanner doesn’t have any ability to correct for that (so far as I know). If present, that should show up as part of the slide sharp and part soft and I’m not 100% positive I was seeing that. In any case, there’s not much to be done about because flatbed scanners don’t have the focus correction ability and like most consumer scanners, the Canon lacks any no manual focus adjustment. This is the one spot that the $500 Nikon film scanner can push the flatbeds out of the way—it has does have an adjustable focus and can compensate for the film curvature. Nice, and enough to use it for the occasional very special image, but not enough to make up for being slow and having clumsy software.

Bottom line: slides hold up well, scan well and produce nice images. But they take a lot of time.
Despite my concern above, the fact remains that these film scans are very nice, in fact it’s a rare print that produced a scan even close to this good.  An interesting comparison turned up as a I did these. In some cases, I’d had prints made from the slides and many of those got scanned in the earlier parts of the project. Although I thought those prints had held up pretty well and made good scans, once I had the slide scanned, it was clear just how much better the slide scan was compared to the print. Better color and far better detail–even with that bit of softness.

Sound like too much effort? Maybe–there are alternatives.
Scanning slides will consume a lot of time no matter what you do. Figure at least a full day to do a 140-slide tray–but go all out, and you’ll spend an hour on one slide!  Once I’m through the ‘family and friends’ group I’m working on, I’ve just gotten a good start, because I’ve got >5,000 more waiting for me that are our vacation and travel pictures (yeah, I shot a lot of film!). I’ve been investigating several on-line services that scan negatives and slides. They range in price and exactly what they do to create the scans. But all should produce scans as good as my ‘normal’ setup does. Shipping my slides somewhere is a little scary although places like Wal-Mart and some photo stores offer scanning as a service–but taking it to a local store doesn’t mean they won’t get shipped somewhere. The tradeoff now changes from time vs. quality to my time vs. my money. One of the cheaper places I found sounds good and does slides at $.39 each. But multiply by 5,000 and that’s not a small investment. None-the-less I’m going to try one or two with a few slides that I’ve already scanned so I can compare results and then decide.

Over to you
Once I’ve got some experience with the services, I’ll add something here. If any of you have actually used any of the services I’d love to hear about your experience with it.

Next:   A few more tips for scanning.
Related: Slide scanning update–getting better results.



About Dick Knisely

Science-guy, engineer, father, grandfather, husband -- yeah, I'm all of those things. I author this blog to share things I care about and you might care about, too. I hope you do and that you'll join in to share things you care about.
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One Response to Some Lessons Learned for Film Scans

  1. Pingback: A tale of scanners, pictures and software (oh my!). Lessons learned. | What I think about that

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