Slide Digitizer

Remember slide shows? The ones that used a carousel projector and real slides? [Brian] wanted to bring his slides into the digital age but was spending far too much time scanning in the 35mm relics. He set to work and built a rapid slide digitizer using a projector, a DSLR, and a microcontroller.

His system centers around an AVR microprocessor, the ATtiny2313. Some DIP switches are used to set the number of slides to be scanned, and the timing for synchronizing the projector and the camera. Using two relays, the cable release for the DSLR and the remote advance pins on the slide projector are connected to the AVR. [Brian] used a macro lens and sets the focus, exposure, and f-stop manual. Once everything looks good the touch of a button quickly steps through the entire carousel at about 1 slide per second. A small video of the process is embedded after the break and his writeup has some comparison photos between a slide scanner and this setup.

[flickr video=]

24 thoughts on “Slide Digitizer

  1. @ Nemo:

    I’m sure you are correct if you timed what was in the video. The projector can only advance at about 1 Hz, and I was pretty lazy with the timing tightness. You can make it run a 1 Hz + the shutter speed you have it set to. I figured it was better to let it settle a bit before the image is taken. So you are right it is more like 0.7 Hz in the video.

  2. Funny, we busted out the old slide projector at Mom and Dad’s this Thanksgiving and had a great time watching slides. Now Dad is all hot to get a digitizer for the slides. Just wish I had a decent DSLR to attempt this hack for him.

    Great hack!

  3. I have been thinking about building something similar and I do not have very much knowledge on the subject. Would this be very easy to do on an Arduino? One thing I dont understand is how you get the arduino to tell the camera and projector to activate. Are most devices triggered with just a single push button type pulse?

  4. @ Jason
    I don’t use arduino as I like to do everything on a really low level, but if you can make an LED blink you can do this.

    As to your other question. Most old wired remotes are going to sense a short or some voltage on a pin. In this case I googled to find out how the 2.5 mm jack on my SLR worked, and it was indeed just a short. You could use transistors to do this project but relays are even most simple and grant total isolation from the voltages on your breadboard, no wish to blow up your digital camera I assume… Also the VDD of the slide projector could be anything… The projector I used has a 5 pin din connector the center is the COMmon pin and the pin at 1 o’clock is the forward pin. I measured the resistance between the pins on the wired remote to make sure it was just a short.

    I don’t know how long the pins need to be ‘high’ to trigger but given that human interactions tend to be 10-50 ms I just set it up to be in that ball park. Works.

  5. Wow, I think I would *pay* for something that does this.

    Every slide digitizer I’ve tried is painfully slow or sucks. There’s like 7 large boxes full of slide trays (50+ shoeboxes, haha) in the crawlspace I’d love to be able to burn through using my dad’s DSLR… or hell, this would be a good excuse to buy a new one!

  6. evilspoons:
    I know how you feel. Even compared with most commercial products it is fast, but doesn’t have ICE or FARE like abilities. If you already have your slides loaded there is a drawback in that they are likely upside down… Also best to make them all landscape or you have to either crop a lot or cycle through twice in landscape and portrait.

  7. Wow that’s very good ! The Canon scanner seems to do some kind of internal softening/noise reduction, so I think you setup is actually better ;)
    As for ICE or FARE, whatever it is, I’m pretty sure it can be replaced advantageously by a batch processing in your image processing software of choice.

  8. My F-I-L has carousels of slides and a slide
    projector. Building this could be a great
    Christmas present for him.
    We don’t have a DSLR, but I have a digicam
    I could probably hack.

  9. @Xtalker

    I perhaps can take some more pictures later. There is nothing to it really. It is just a empty tube with the slide at the end with the light behind it. Check back on my site I guess when I have more time I might add more extensive documentation.

  10. Ditto the request for more info on the diffuser. From your last comment, it almost sounds like you have the diffuser between the bulb and the slide. So you’ve created a carousel-fed light table, and you’re focusing on the surface of the slide itself?
    Thanks for the initial write-up and video! Looking forward to more!

  11. @Brian,

    Neat hack, but I got horrible results using an actual slide projector setup (like yours) when I tried scanning my father-in-laws 60 carousels of slides. The illumination was uneven and of very poor color balance. I cleaned the diffuser, I replaced the bulb, I even tried buying (and quickly returned) a slide projector “copy box” to contain the process, but nothing helped.

    There was really no way to get images out of the slide projector that did justice to the original photos.

    I ended up purchasing a Minolta Dimage Scan Dual II film/slide scanner (this was quite a while ago, and I swear I’ll never use USB 1.2 for anything dealing with images ever again), tossing out the packaged software and using VueScan from Hamrick software. The Dimage is a tray-fed slide scanner that scans four slides at a time. With two trays I can load one tray while the other is scanning. It scans up to 11MP resolution on 35mm slides (2910 DPI). The process was slow because of the crummy USB, but the quality of the images was far superior to anything the projector setup could produce. And it wasn’t all that bad, as I used the time it spent scanning to rotate, crop, and correct the previous tray’s scanned images.

    If you’re seriously looking to archive the slides, I’d definitely recommend a dedicated film scanner.

  12. @Everyone. I have added details about well everything…

    I may run out of bandwidth this month as a heads up as I have had many visitors at this point…

    You may build one, but be warned if you do my slides of choice could be atypical. I don’t think they are but they could be. The example slide is the target for the exposure I set the camera to.


    I have (had) that exact scanner… I gave it to my father. It is very slow compared to 1 second.

    The uniformity is not a problem so far for me. You do need to diffuse it well though I took blank frames to check if it was “good enough”. With just paper it isn’t good enough. With paper and my plastic diffuser it seem to be ok.

    The intent of this project is to make a quick copy of everything. The best slides should be scanned in a good slide scanner. Such a scanner cost more and I felt the comparison would be better to do against a flatbed which many people will have.

    Color is a complete non-issue, as I remarked on my website, shoot RAW if you need to fix it then you can. Color casts are going to come from the emulsion support layer of the film (negatives are orange for instance). But you can correct for all of that in software.

    1. I really wish to help my dad scan his 6000 slides or more and of all I’ve read your solutions seems to be the more logic, If I need it to do it manually is it possible?? I just dont seem to get how to do the autoshutter thing, please if you have any advise I will really appreciate the words of wisdom and is it possible to make it with todays powershots (with macro lens?).

      Alejandra Torres

  13. I used a slide scanner to do 600+ family slides. Came out good enough – all saved to HUGE TIFF files and later software batch processed and shrunk to jpegs for computer/DVD viewing. Now I’m wondering how to capture home movies onto DVD or the computer…

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