Interesting setup. I wonder if you did tests with infrared scratch removal by using an infrared light source for a second exposure? Or flash plus IR filter. It would not work with most b/w film, but probably with some. I am especially interested in difference in focus between both. And if it works in general for such a setup.
I’ve been trying to find out if this is possible but so far no definite answers. That said, a good cleaning does wonders. For 35mm slides I use a bulb blower, then press on 3M transparent tape and pull off (don’t rub across the film surface or it will leave residue), then another blow with the bulb blower. For mediium and large-format negs (not mounted) I use a blower, Kim Wipes or anti-static cloth, then again with the blower. For badly scratched slides you can always wet mount using Kami, Edwal No-Scratch or a light mineral oil. Kami is nasty stuff and I don’t use it anymore. For bad scratches, wet mounting is far more effective than infrared cleaning.
Having a diffused light source through white plexiglass will get rid of all but the worst scratches, much the same as a diffusion enlarger when compared to a condenser enlarger.
I don’t normally clean up the images at 100% size on screen. Just clean up what’s visible at screen size, then do a more thorough clean up on demand, i.e. when an image is needed for printing large. The screen size cleanup is generally quick work, maybe a couple of minutes, after the blower, tape and cloth methods.
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Thanks for all the info. I am using only a bulb blower, but I wonder what 3M transparent tape you are using. I only know the sticky tape that uses some glue, but I don’t think that’s what you are talking about. Is it something electrostatic?
If you have the opportunity to test with infrared light source, I would really be interested in the results, since used with a scanner this technology is a miracle. It would really be great if it could be adapted to a camera “scanning” workflow as well. But I did not find information on how much the defocusing due to different spectrum is a practical issue or a myth, and if such a technique would lead to some reasonable results. But since I have no test setup, I did not have an opportunity for tests yet.
That is 3M Scotch Matte Finish Magic Tape. Yes, it is sticky but I haven’t seen any evidence of residue if it’s pressed on, then pulled off without moving the tape across the surface of the film. I used to use film leader tape, which was used to hold film to the leader as it went through processing machines, but now it’s old and not sticking well enough. I’d be open to other suggestions for this.
Here’s a bit about dust and scratches. Gimp ‘dust and scratches’ filter | Clever Caboose
It’s not infrared, and I’d love to see an infrared solution. That said, if the film is in decent shape, and it’s well cleaned, it’s not as much of an issue as it might seem.
- Bring in photo
- duplicate layer
- One the upper layer apply “remove hot pixels” filter with settings about 6 or 7 on both. This will get rid of the small specs, but not the larger ones.
- That also loses a bit of fine detail, such as in hairs or eyelashes. So on those areas use a mask to expose the image underneath.
This is actually very effective, especially for scanned slides that have a lot of small specs of dirt. It’s still necessary to clone or heal the larger ones but that doesn’t take as much time.
Chris, do you have any thoughts on how infrared cleaning would work with a DSLR? I’m guessing this is a 2-step process:
(1) using infrared to identify the defects and creating another image that shows these defects and nothing else.
(2) an process that would automatically apply something like a healing brush at each defect.
Vuescan, for instance, allows you to save the infrared as a separate channel in a raw file so you can process it again with different cleaning settings without re-scanning the original film. it would be great to have a similar option for DSLR scanning.
I documented some of my findings along the following thread (scroll down a bit to see some example images).
The photos I am scanning are old family photos with some of them already in a very poor condition, therefore infrared is particularly helpful since it separates scratches from other degradations.
This is what I am doing, the process and how it came up is documented in the other thread as well. I am using G’MIC for the tasks, especially the inpainting algorithms that are available in G’MIC lead to much better results than the vuescan algorithm (a comparison is available in the thread as well).
I think it could work similar with a camera by taking a second photo with an infrared light source. But there might be some defocusing due to the different wavelength that passes the glass of the lens. But maybe that’s not an issue, depending on the amount of blur added. Would be interesting to do some tests, but at the moment I am lacking several parts of the setup.
However, not a good option for most b/w images since the silver particles may block the infrared light. So probably not a solution for you, but for colour images it can be magic.
As you say, IR cleaning doesn’t work for silver-based B&W films, but it would still be very useful for colour films. When I have a bit more time I’ll read your other thread in more detail and try to follow the steps with a colour scan. Thanks.
Chris, do you know if the IR channel would show defects on both sides of the film, or would it require two IR shots, one on each side?
I cannot observe any difference on if the film is lying upside down or not (I had several scanned upside down by accident since for old film it is often not easy to detect the emulsion side correctly), so I would conclude that it shows defects on both sides. As far as I understand it is a transmitted light technique. But this is only out of experience, I did not do a direct comparison.
Wouldn’t the IR filter in the DSLR interfere with that?
I am not sure. Interfere, of course, but it may be nevertheless feasible, tt may depend a little on the actual frequency and on the power of the infrared light source.
There are “screw-on” filters sold that block visible light to allow for pure infrared exposure (marketed as “infrared filter”) which give the impression that the cameras do not entirely block parts of the infrared spectrum. For the application of film scanning, doing the infrared exposure at much higher iso values may be feasible to account for losses due to attenuated infrared spectrum. And/Or to use more power at the emitter. Furthermore, one would not have to use the entire dynamic range of the sensor, since the goal is a b/w mask anyway. To get a reasonable feeling, tests are required, and since I do not own everything which is required to do it myself, I try to collect indicators that allow for better understanding of the whole topic.
Thanks for showing your setup, it was quite similar to mine 
I only used an Artograph LightPad as my light source, and my camera was hooked up to my pc for tethered shooting. I used DigiCamControl, which has a really nice ‘focus’ functionality that helped a lot in setting the focus just right. This was especially useful when the slides had been slightly damaged or wrinkled.
Still a question: how did you take multiple shots of the same slide? Your setup looks quite immobile.
I’ve only done a bit with tethering, mostly with Entangle, but should try DigiKam for that as well. Have you compared the two?
The film holder I showed in the photos is only for 35mm and there’s no reason to shoot multiple shots as even 24 mp exceeds the useful information in the slide. For medium and large format film I can move the holders around to get multiple shots. But even that 35mm film holder can move around easily.
I’ve been experimenting with light pads as well. While they are very convenient I’m finding two issues. First, my copy stand is not as sturdy as some, such as the Manfrotto. This means there is slight vibration which makes the images not quite as sharp as they are with the flash. Second, with one of the LED panels, the CRI (colour rendering index) is not that great, resulting in slight shifts of some colours. I have a better light pad on loan from the store and it seems more accurate for colour, but there’s still the sharpness issue. With ISO 100 and f8 on the lens, the shutter speed is 1/15 second, which is the worst shutter speed for vibration. I have an LED video light which is much brighter and gives me 1/250 second, thus sharper images. Still working on this as the light panels are more convenient.
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I believe all the tethered shooting options use gphoto2 as the backend, so they should all be fairly similar. I was happy with Engtangle and thought it was a nice solution.
I, too, have a similar setup (with a lightpad). Didn’t yet think about the vibrations, good point. I shoot color slides with bracketing (Magic Lantern) and merge them with HDRMerge.
Best,
Flössie
Flössie, just wondering if you’re shooting these raw. I’m shooting raw, processing in Rawtherapee and I really don’t think I have any clipping of highlights or shadows when carefully compared to the original 35mm slides or other film types. The dynamic range of the raw files is much greater than that of slide film.
Scott, I somewhere read it was 14 EV for slides, and my Canon isn’t a DR beast. I used Magic Lantern auto-bracketing and it produced three to five shots each 2 EV apart. But I usually throw away the brightest one(s). So basically two shots usually do. And it could well be, that one was enough, maybe I was overcautious…
Ah, and yes: I shoot raw, I must confess. 
Flössie, I’ve noticed a significant improvement in both shadow and highlight detail when I started using a DSLR for scanning instead of a scanner, with the same slides or negatives. For instance, when zooming into dark shadows, slides I scanned with other scanners such as the Minolta Dimage Multi Scan Pro with Vuescan show noise and posterisation. The D800 scans are very clean in the same areas, with smooth transitions between the dark tones.
Similarly, I re-scanned some medium and large-format B&W negatives with the D800. The improvement in dark areas of the final image (light areas of the negative) is striking when compared to scans I did on an Epson 4990 with Vuescan. I don’t know whether this an issue with the scanner hardware, Vuescan software, or the setting I was using with Vuescan.
Do you have any experience with color negatives? I bought a KB12/80B filter for not clipping the red channel too early but had troubles getting good colors back in RawTherapee. I showed one example to @Morgan_Hardwood and he suspected the filter for my problems. Maybe I’ll give it another try without the filter this year if time permits. BTW, I also use the Sigma 70 2.8 EX for the job.