SlideSnap Pro Modification by AKADAP

Last crawled date: 3 years, 1 month ago

This is a modification to the SlideSnap Pro: https://slidesnappro.com/
At the time I bought a SlideSnap Pro, they had two models, the SlideSnap Pro, and the SlideSnap Lite. Both are based on a refurbished and modified Kodak carousel projector.
The Lite came with a Canon G-16 camera and a macro lens adaptor, the Pro came with hardware to mount a DSLR, but no camera.
I had inherited a Canon G-16 camera from my father, and was not quite sure that the G-16 had the resolution to capture all of the resolution available on a 35mm slide, so I decided to compromise. I bought the Pro, and the macro adapter lens.
I had to do a bit of tweaking to get this to work because the lite still has the lens barrel in the projector to allow the macro adapter to just slide into place, but the pro has the lens barrel removed from the projector to give the dslr a clear view of the slide.
I captured a couple of rolls of film with this setup until I got to a slide with the license plate of a car in the lower left corner. I was trying to date my grandfathers slides, so I tried to read the year on the plate, and found it illegible. I took the slide to my microscope, and could easily read the license plate year. This proved to me that the G-16 with the macro adapter was inadequate.
I attempted to find a lens/camera combination that was adequate to capture all of the resolution of the slides, but the only data I could find was relative information. This lens is better than that lens, but nothing about absolute resolution. I gave up on finding absolute information and bought the best combination I could afford. This was a Sony A7RII with a F2.8 90mm macro lens. This proved capable of resolving the grain of the film. I don't need any better than that. The camera eats batteries quickly, even when turned off, and focuses slowly, but it is adequate for the purpose of digitizing slides.
The lens is big enough and must be close enough to the slide that I had to trim back some of the plastic on the projector. I also needed to remove a piece of sheet metal from the mechanism that was blocking some of the lens' view of the slide. Luckily, this piece of sheet metal was only meant as a light mask, and did not serve any structural purpose, so it was easy to get rid of. Included is a photo of the piece of sheet metal I removed.
The Slide Snap Pro comes with a camera alignment system that I found to be inadequate. Part of the alignment procedure is to mount a target on the lens to ensure that the camera axes is perpendicular to the slide, by focusing on the target through a special mirror slide. But once this procedure is done, the target must be removed from the lens. Since the end of this lens is inside the case of the projector when the slide is framed properly, the camera must be removed from the mount in order to remove the target. The problem is that the mounting system is not repeatable. It is the same crummy single quarter twenty screw used on most tripods. Also, adjusting any of the adjustments on the mount affected all other adjustments, so it was impossible to line the camera up correctly.
This is where this modification comes in. I bought this x,y,yaw stage:http://www.optics-focus.com/xy-axis-plus-rotation-stage-p-1033.html
and used it with the z, pitch and roll adjustment part of the stage that came with the SlideSnap Pro. I 3D printed standoffs to account for the taller profile of this stage, and printed a mount to allow this stage to be mounted to the frame. These are the parts included in this "thing". I also used a quick release that came with a 3 legged thing tri-pod which had a pin that allowed the camera to be removed, and replaced repeatably in the same place.
The system is not perfect, the X axis is sufficient to frame the slide once the carriage is mounted in the correct location for that slide type, but different slide types require moving the mount closer or further from the projector for proper framing. I avoided most of this problem by setting aside the odd sized slides, and doing them last. I included a photo of the different size slides I encountered.
The threaded spacer must be printed with enough wall thickness that you can tap it with threads.
Note that the two lines indicating mounting points are incorrectly placed, and even if they were correct, could only be correct for one camera & lens combination.
A newer version of the SlideSnap Pro has been released. I know they have updated the electronics, but I do not know if they have changed any of the mechanical elements.
Note that this is the 3rd iteration of attempts to make the alignment reasonable. The two previous attempts were failures for various reasons, so I did not publish them.
Notes about cleaning slides. I found canned air inadequate. It was common for people to smoke in the 50's, and I found that some slides had dust glued to the surface. For most slides I could brush off the dust with a brush designed to clean digital camera sensors, but some required cleaning with a q-tip and a film cleaning solution. I used PEC-12. I used this solution as little as possible because even a cotton q-tip will scratch the emulsion a little bit. I found the fine scratches left were not visible, but I did not like damaging the emulsion. PEC-12 did not dissolve all of the substances that were on the slides I scanned, but most of the time it worked. Gunk on the slides seemed to be cigarette smoke sometimes, and leftover developing chemicals other times. Most of the time it was just dust that could be brushed off.
The camera would occasionally fail to focus, and others incorrectly expose the pictures. I would review the results before unloading the carousel, and re-take the mistakes. It took more time to load and unload the carousels than it did for the SlideSnap to sequence through them.