Taking Pictures of 35mm Slides

Many families with members over the age of 35 have 35mm slide collections, some of them quite vast.  To keep these memories from being lost, most people send their slides out for scanning.  In doing so, you have a choice; either pay someone a tremendous amount of money to do it, or do it cheaply and have them sent overseas.  In tackling the Greg Schlack project, I didn't really find either option attractive, as there were more than 8,000 slides in the collection, and even doing it cheaply overseas would have resulted in spending more money than I was comfortable with.

So I did it myself, without a scanner.

To do it, you'll need a decent-quality (12MP or greater DSLR) 35mm digital camera, a 35mm slide projector, a macro lens, a tripod, and a couple of ND filters.  Basically, you just take a picture of each slide.  Big thanks go out to my good friend Dave for forcing me to document the process!  Here's how to do it:

1.  Set up the projector as though you're getting ready to project the slides.  You'll want to be sure the glass lenses between the bulb and the slide are clean, so you might want to clean them before you set up.  A scratch or smudge on one of the internal lenses will show in the final product as a dark blob.  Important note:  If you should happen to touch the bulb, be sure to REMOVE the bulb and clean it with alcohol.  The oils on your fingers (even a tiny amount) will cause the bulb's glass to heat up at a different rate than the clean portion, and will cause a glass blister on the bulb or even an explosion.  Either will burn out the bulb, and they're (relatively) expensive to replace.  I can tell you all that from personal experience.

2.  Remove the projector's front lens.  This procedure varies from projector to projector, but will usually entail either tilting the focus knob up, which releases the lens, or in the case of less-expensive projectors, just rotate the focus knob until it pushes the lens out. 

3.  Using a tripod, position your camera so the macro lens points down the now-empty throat of the projector.  The distance you'll need to use varies with the lens, and could be anywhere between six inches and 18 inches from where the slide will be.  Be sure to get the lens as perpendicular (and not rotated, with relation to the slide!) as you possibly can to the internal mount for the slides.  Having it off-axis will cause you to be in focus on one part of the slide, and out of focus on another part.  You'll be able to see this error easily once you get to a computer (or wherever you're viewing the final result), so just do a few to start. Another sign of failure to be perpendicular is Keystoning, a term from the silent-film projection era when projectors were pointed upwards toward the wall.  The top of the projected image was wider than the bottom.  I suggest mounting your camera normally for ease of use, but you can also mount it upside-down to avoid one extra step later, which is turning your image upside down.  More on that at the end...

3a.  If your lens will focus to a maximum distance of only a few inches while in macro mode, you won't be able to use this method, as the slide will be about five inches inside the projector, and your lens won't be small enough to get inside that assembly.

4.  The projector is bright, bright, bright!  You'll probably need to expose as fast as your camera will allow, though the final settings will depend on your distance from the light source.  I used ISO 100, F16, 1/4000, and still had to have two neutral density filters on the lens to let even less light in.  I set white balance at a little cooler than daylight, but you can adjust it later if you're shooting in RAW, which you should be for this project. 

5.  Before putting the slide tray in place (making sure that inner ring is in place also!), blow air around the slides to remove dust.  You can remove the dust in Photoshop, but doing it for a thousand slides will make you hate your life.  Blow all the way around the tray.  The advantage of the tray is that the compressed air can get around both sides of each slide during the blowing process.  This will blow the dust into the air, so also blow over the top of the tray to try to keep that same dust from settling back into the tray.  Don't go crazy - you can't get rid of all the airborne dust.

6.  Turn the projector on, set the first slide, and work with the camera to get the entire slide in the frame, at the right exposure and focus.  Some macro lenses will be better suited than others, only because of their magnification size.  I suggest using a remote shutter release.  The exposure is super fast, so you won't get a blur if you click the shutter button by hand, but it's possible you may move the camera just a bit when pressing down on the shutter, making your alignment a tad off.  But doing that isn't a requirement, just an option.

7.  Take your first picture, and set the next slide using the projector's control.  Since the projector places the next slide in exactly the same place, you shouldn't need to readjust focus for each slide.  I checked focus about every forty slides, but I'm not sure that was even necessary.  When you've done a handful, stop and take them back to the computer to look at them for dust, Keystoning, and general and off-axis focus.  If you use an image editing program, make a selection around the edges of the visual portion of the image.  Looking at those perfectly straight selection lines will tell you right away if the slide is tilted or Keystoned.  Make your camera/tripod adjustments if necessary, and try a batch again.

When you turn the projector off, make sure to leave the fan going for ten or fifteen minutes afterwards.  It's amazing how much heat builds up inside those things, and the bulb will burn out more quickly if left to cool without the fan.

For me the most time-consuming part was putting them all in carousels, so I abandoned that portion of the idea pretty quickly.  If yours are already there, then that's a huge timesaver.  Having them in carousels will also orient them partially correct for taking their picture.  The projector flips the image horizontally and vertically when projecting, so looking down the projector throat (essentially looking at the projection backwards) will reveal an image that is correctly oriented left-to-right, but is flipped vertically.  This will need to be changed at the computer in one of several ways, but the easiest is to open Windows Explorer, navigate to the directory the images are in, and select them ALL.  Then right-click, and select Rotate Image Clockwise.  (It'll take a few seconds if you have many hundreds of images.)  Then right-click again, and select the same item again.  This will rotate all your images 180 degrees.  You could also mount your camera upside down if you want, and eliminate that step.  But doing that sort of freaks my brain out when shooting, so I'd rather do it later, and use the camera like I'm used to.

Since I abandoned using the carousels, I instead used the Kodak B40 Stack Loader, which allowed me to transfer stacks of slides at once from the metal trays they're stored in.  This was much faster than loading them one by one into a carousel. I picked one up on Ebay for sixteen dollars.

If you've put your vertical slides in vertically for viewing, be aware that those will require a larger area to be photographed, so you'll want to have a compromise zoom amount to get more area than you would otherwise need.  I had all my verticals horizontal, then rotated the images that should have been vertical in a batch on the computer after the whole process was done.

As you can tell, there's some post processing work to be done on each slide, but if you've been careful about your settings, you'll be able to set up an action to do the same thing to every slide, saving you hundreds of hours of work.