Engineering Project – Re-inventing the 35mm Color Slide Digitizer

I can’t help myself. When I get it in my head to create a solution or solve a problem, it doesn’t matter that it has already been done before. I love finding a quick, in-expensive solution to a need. In the 1970s and 80s, my film of choice was 35mm Color slides; I enjoyed making slide shows.


I haven’t yet digitized these photos, so my kids haven’t seen many of them, including pictures with them as small children. It’s time to change that.


Now I know that I can purchase a digitizer for 35mm slides; but, “where’s the fun in that?” I have a smart-phone with a digital camera and amazing pixel resolution, and I understand the basics of light and optics to give it a shot. So one evening, I grabbed my grand-kids favorite box of Lego’s® and went to work, for fun of course.


Requirements: 1) a way to hold the slide a fixed and steady distance from the camera, 2) a way to illuminate the image, and 3) a digital representation of the image good enough for social media.


Concepts: 1) a structure to hold a light source, a light diffuser, a slide holder, and the camera (see picture), try variations and lengths (don’t worry about the color of the structure.)


Design: an electric Christmas candle mounted to a base, a light diffuser cut from a white paint bucket lid or plastic putty knife, a support for the slide, and an adjustable support for the camera

Image Processing: place slide in holder, turn on the light, avoid stray light, assure that the camera does not focus on the diffuser, focus on the slide, take the picture, crop the image, adjust the color as necessary, post and enjoy pictures with family and friends


Lessons Learned: the camera can’t get close enough to the slide to utilize all of the camera pixels therefore some resolution is lost (still okay for social media)

Conclusion: Great project, lots of fun, and included one of my favorite activities; that is, walking through a hardware store looking for suitable substitutes for what I really need. In this case, a high density plastic light diffuser. Enjoy the results, and keep on engineering. Go ahead; share this with your friends. Better yet, get that old box of slides out of your attic or basement, and share them with family and friends.

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2 Responses to Engineering Project – Re-inventing the 35mm Color Slide Digitizer

  1. Kelly Marcum says:

    Nice project and great solution!!

  2. Don says:

    Wonderful post. Great reminder of the family slide shows we had growing up. Thanks for prompting me to go down memory lane.

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