Process for digitizing photographic slides

Digitizing old 35mm photographic slides can give otherwise forgotten photography a second life. Film slides can have incredible detail, and the reveal can be quite a surprise. From time to time I convert a hoard of old photographic slides to digital. Here's my improvised DIY process. Of course, if you have the time and money, the easiest way to do this is probably to ship yours out to a professional service provider and have them do it. Lately I have noticed reasonable prices for this service, although I don't have experience working with a service provider.

I digitize slides by photographing them against a light box that rests on an easel. I use a macro lens and get good and close to fill the image sensor as much as possible. Camera is on a tripod and I use a remote sensor to snap each photo. 

While there are many ways to digitize slides, the method I explain here – photographing them using a light box to hold and illuminate them – works best for me when I want to quickly convert a few hundred slides. It's based on equipment I already have in my studio, gives me an efficient workflow, and requires minimal retouch after shooting. It also gives me sufficient resolution for my own printing and display purposes. There are other methods that are much more time consuming and might require specialized equipment that I don’t have in my studio but can result in higher resolution images. Higher resolutions may be required for certain types of projects, but also carry the down side of larger file sizes. 

Surprisingly, my scanner was not the right solution for me

Initially, I wanted to use my reliable flat-bed scanner to do the job. It came with a slide holder that snaps in place on to the glass and is used specifically for this purpose, but scanning this way ended up taking too long and was not practical. The slide holder holds only four slides at a time, and each pass at full resolution takes over two minutes. Loading and unloading the slide tray was also extremely fiddly. I love my scanner, it’s a real workhorse, but using my scanner this way was just not going to be the right solution here.

Using my camera with a light box

As an alternative, I developed a process to individually photograph each slide using my Nikon DSLR with the aid of a light box. To maximize resolution I get my camera close to the slide and fill the camera’s viewfinder with the slide image as much as possible so that I don’t have to crop out the cardboard or plastic border around the image later. Having good resolution on your camera’s digital sensor is super helpful here. The current version of my camera has a 24 megapixel sensor, and I estimate it would yield a maximum ppi of over 6000, which is huge. (My older camera has a 12.3 megapixel sensor and I estimate a maximum ppi of around 2800, assuming no cropping, which is pretty good for how I use these images.)

To hold and illuminate each slide, I set them against a light box propped up almost vertically on my easel. I happened to have a pretty decent light box from an old animation project on hand. A light box can shine a lot of bright white light through the slide while it is being photographed, which is ideal (and basically the same way a scanner or copy machine works). On the light box I set a little strip of wood with markings to ensure consistent positioning each time. (Prior to arriving at this set up, I tried photographing using a hand-held slide viewer to hold and illuminate the slides, but I was concerned about the quality of the built-in lens on mine and the possibility of vignetting. I also considered projecting the slides onto a screen and photographing those, but I did not want to rely on a 40 year old slide projector.)

To minimize camera shake I set up my camera up on a tripod. I position the camera close the slide so that the image of the slide fills the frame as much as possible, but is far enough away to allow the camera to focus. The lens that works best for me is my 18-55 mm lens, set at 55mm focal length. I attach a 10+ macro lens which lets me just about fill the entire frame with the slide image. (You can also a combine a series of macro lenses – I have previously attached a stack of macro lenses in the series +4, +2, and +1, with +1 attached closest to the camera and +4 closest to the subject.)

Camera settings are pretty straightforward.

  • I use aperture priority mode. Normally with a macro lens you want a maximum depth of field and would use a small lens aperture (denoted with a larger number – f/22 is a pin hole, f/2.0 is quite large). However, since the slide we are photographing is flat, maximizing depth of field is not really an issue here. I set the aperture wide, to its second-largest opening (lenses can be susceptible to vignetting at their most-open setting). On my lens, fully extended to 55mm, the largest the aperture can get is f5.6, so I take it to the next click down to f/6.3.
  • There is plenty of light coming from the light box, so I can turn up the sensitivity on my ISO (i.e., to a low number, 200 or less) and get a lot of detail.
  • Since the camera is stabilized on a tripod, shutter speed is not really an issue. To minimize potential camera shake further, I use a remote shutter release so that I did not have to touch the camera at all while shooting. With the camera so stabilized, how long the shutter stays open is not really an issue.

After my camera and light box are set up, I position the first slide and focus the camera. Once the camera is focused to the first slide it does not need to be refocused, so I turn the lens to manual focus mode and the camera won't make any additional automatic adjustments while I am shooting. I manually “advance” the slides, placing, photographing, and setting aside each one. I keep the remote trigger in my hands as I move the slides, and snap the photo as soon as the next slide is in position. I can move through a stack of slides pretty quickly like this.

Once the slides are photographed, I transfer them to an external hard drive that I use exclusively as a photo archive. I crop and do light retouch in Adobe Lightroom (mainly white balance and color). There are macros you can set up to automate some of these steps in Lightroom. Finally, I safely store the old slides in proper file boxes.

Cropping and making adjustments in Adobe Lightroom. The original slide is over 40 years old and gets a new life as a digital image.

Note on equipment used: My camera is a Nikon D5000 and the lens is a Nikor DX AF-S 18-55mm 1:3.5-5.6G. I use a Hoya 10+ macro close up lens. My light box is a Huion Tracing Light Box (19"L x 14"W, with a black frame). I store old slides using Archival Methods slide file boxes.

Follow the author on Twitter @tj_katopis.