What are the major differences when digitizing slides/negatives with a DSLR vs. a scanner?

Question

A flickr discussion, pointed in an answer to another question, got me excited in scanning old slides & negatives with a tripod, lightbox, macro lens and a DSLR (or with a similar set).

I have rather minimal experience in scanning with a flatbed scanner and non-existent experience with slide or negative scanner. So: what would be missed from a dedicated scanner when digitizing with a DSLR (if one already has the sufficient gear)? What generally are the major drawbacks? Or will a DSLR excel in some aspects?

Resolution is something that my Canon 450D probably wouldn't match to the 4000+ dpi that scanners offer, but that's probably something I could cope with (or is it?).

I'm aware of the possible alternatives mentioned in older questions, but I don't consider them as interesting right now.

Answer 1

I'm the originator of the flickr discussion, and I'm flattered that it's thought to be worth reviving here :-) I went through the process mainly for archiving purposes. The fear of losing these personal negatives was much more important to me than technical quality. Whatever I did, it had to be fast so that I could do every single one of my negatives. I would say that if you have the space to leave the tripod and camera set up for a day or more, it's a decent solution for large numbers of 35mm colour negatives or transparencies. I'm not sure the resolution is sufficient for medium format colour or even 35mm fine-grained black and white film. I'm also not sure it's ideal if your intention is to display or print the majority of them. While the dslr raw files are flexible and high resolution, producing a decent print from one does take a fair few minutes of post processing. But as I said in the original thread, once setup it's very quick. You can rip through a 36-exp film in a couple of minutes.

tl;dr: Good for archiving large numbers of 35mm colour negs. Not ideal for fine art purposes or ongoing digitisation of new films.

Answer 2

A better negative scanner (like my Nikon Coolscan V) has one tremendous advantage:

• dust/scratch removal (ICE - Nikon, FARE - Canon)

That is (in my case) done by an extra IR-lightsource that adds the information of bumps and scratches that can't be part of the picture. I once tested it with a now about 40 year old dia-positive of my father: without ICE it looked bad, with ICE like it was taken yesterday ... in the 60s in Prague ;) (Edit: it is said not to work with BW-films - I guess the reflection-spectrum is different)

In my experience there is always a hair or some dust on a negative you had stored as we amateurs do store stuff.

Edit:

One thing that I use often is Multi-Scan, offered by better scanner software (like Vuescan or Silverfast). The result is that you lower the noise - the impact is visible. That could be reproduced with a DSLR and image-stacking. I really don't know if this is important today, as the DSLR-sensor is at least five years younger and a lot less noisy.

Edit2: as I'm just scanning some badly stored diapositives from about 25 years ago, let's take a look at a sample: .

Answer 3

The quality from a DSLR photograph might rival a scanner if you get the macro lens properly positioned, but I'd say the big thing you'd lose is time. Hours and hours of time. It will take forever to line those slides up properly for each frame, and then you're going to have to spend some time on your computer rotating slightly, cropping, and doing lens distortion correction to get a workable negative. Looking at the setup on that thread you link to, I just cannot imagine spending all that time hunched over something, fiddling with the negatives, trying not to exhale too deeply and unseat it all.

Unless you only have a few frames to do or think this would be a "fun project" (I don't), I would stay away. Can you not send them off somewhere to be done? Or get a used scanner on Craigslist?

If you want to estimate quality, you could get a rough sense of the resolution using the megapixel count of your camera with the size of the negative in capture. For instance, your Canon has 12 MP. If your macro lens will let you get close enough to have the negative fill half the frame (70% in each direction), you'll be getting about a 6 MP image.

EDIT: Based on comments it seems like this is more of a fun DIY project request, which I guess puts it in the same category as pinhole cameras and such. Which is totally fine, of course.

But I maintain that the most efficient way to get good results would be to send them off somewhere reputable, and the second-best would be to get a dedicated scanner. It's true it might take a little longer in absolute time, but a quick check on Amazon shows several entry-level negative scanners that can do a frame in less than a minute at 3000 or 4000 dpi. While the Flickr thread does mention that things get going quickly once you're set up, there are also lots comments like "Getting the color balance right is really time consuming and it's driving me crazy" and the instruction to "fiddle endlessly with the tripod to get the focus and framing exactly right." I'd rather load a negative scanner up with 4 strips and come back in half an hour.

Answer 4

If you're going to copy slides/negatives by taking a picture with the camera, you almost certainly want to get (or build) something closely akin to a slide copier -- something like a set of extension tubes to screw onto the filter threads of the lens, with a little holder on the end that will automatically hold the slide/negative aligned and at the correct distances for a 1:1 (or just less than) copy. This pretty easy to do for slides, but quite non-trivial for negatives.

Once you've done that, the main thing to deal with is assuring you have even lighting. To get that, you'd want a few layers of diffuser between the slide/negative and the light source. IIRC, when I built one I used something like three layers of plastic from a milk jug with some white cloth in between. It may not have been the best, but it seemed to work all right. I believe I also built a small bracket onto the end to mount a flash onto (the copier got lost somewhere along the line, but I still have the trusty Vivitar 283). Since you're shooting at a fixed distance (etc.) a manual flash really isn't much of a problem to get set up and working.

Answer 5

Wet mounting (sealing the film with fluid between scanning surface and clear acetate on the back, or between film and an acetate sleeve around it) often used in drum scanning, also available for flatbed scanners, is probably something you will skip with your DIY dSLR setup. According to an article By Bill Glickman, it greatly enhances clarity of the film, blends film grain unnoticeable and removes most scratches and dust.

ScanScience (a supplier of wet mounting products) also claims richer colors and better dynamic range.

The technique does take some tinkering though. For example, David Mantripp first reported minor improvements with slide film probably not worth the hassle and later admitted clear benefits with negative film.Thomas Robinson has also demonstrated clearly enhanced results with old black-and-white nitrate negative.

Answer 6

Bit-depth may also differ between a DSLR and a scanner. According to the Internet, a higher-end DSLR will provide 14 bits of information per channel when shooting RAW, while 10 bits per channel is more common for more accessible DSLRs. Either way, you must shoot RAW to get more than 8 bits per channel for any DSLR.

By contrast, the cheapest flatbed that can scan negatives will readily provide 16 bits per channel. Also, there's also the fact that you close the lid of the scanner which creates a good dark environment and the light-source of the scanner is tightly controlled. It might be inconvenient to light-proof a room and set up a controlled light source that does not add ambient light. The DSLR will pick up on the ambient light.

EDIT: Bit depth is so important when digitizing negatives because after digitizing a color negative, you must apply some color balancing to bring back the natural colors and remove the orange mask of the film. You end up expanding a small part of the color information into the full contrast range, discarding the rest. You'll probably only use 30-50% of the information in the raw scan. With 8 bits, the discarding and scaling will look bad.

Answer 7

A great scanner will normally do a better job because it can hold the film flatter. But I said a great scanner. If you are just shoving the film into a carrier or slide holder, you aren't doing that much better than you would with a DSLR and a macro provided you could create a jig that would line stuff up right. But the scanner is the right tool for the job.

Digital ICE is both good and bad. The great part is you don't spend as much time in Photoshop removing dust and scratches. The bad part is that how the dust and scratches disappear is left up to software and it can make a bad call, rendering a scan unusable. It works more often than not, but at some cost in sharpness.