Many years ago, colleague aviation enthusiast Roel Reijne first posted a way on the Internet to digitize slides using a DSLR. This article is a tribute to this method and meant to spread the knowledge and share experiences. Basically, the way to digitize the slides is to take individual pictures of each slide. That is the short version, but there is of course a lot more to it. The described process in this article is just an example, please let us know if you have any additional insights!
In this set-up, we used a Canon EOS 5D Mark II but any DSLR would do. Having a full frame sensor gives a bit of advantage when using Macro lenses but is not a must. We have not tested with other types of cameras (compact, mirrorless) so if you have any experience with that, let us know!
To prevent quality loss, a Macro lens is recommended. Most Macro lenses are designed for photographing objects from close by, and therefore have so-called reproduction ratios of 1:1 or better. A reproduction ratio of a lens is the ratio of the subject size on the sensor to actual subject size. So, 1 centimetre of the size is reproduced on the sensor as 1 actual centimetre, minimalizing loss of quality. Besides that, a Macro lens has a small minimum focus distance, the distance between the subject and the sensor (so not the end of the lens!). The focal plane mark on your camera indicates from where the minimum focus distance should be measured. In this example, our lens has a minimum focus distance of 31 centimetres as can be seen on the outside of the lens.
In this method, a tripod is a must. As you will be working with low shutter speeds it is virtually impossible to do this without a tripod. The tripod has to have a head that enables you to position the camera pointing downwards, but other than that any firm tripod will do.
To make sure the slide is sufficiently lit, you will need to place it on a lightbox. Important is to take into mind that the light source needs to be even, and the surface without any relief as this will be viewable on the photographed slide. In the past, lightboxes were illuminated with lightbulbs, making even distribution of the light difficult. Nowadays, affordable lightboxes with LED lights are widely available. In this test, we used an Artograph Lightpad 920, but there are many different types available.