Digitising slides with your phone or a slide scanner

Many families still have a box of slides somewhere: a few trays from the projector, loose boxes from the photo lab, sometimes hundreds of holiday pictures from the sixties and seventies. The projector is usually long gone, so nobody looks at them any more. With a phone and a light source you can turn them into digital photos over a few evenings, and for large collections there is the slide scanner.

Why a slide is different from a print

You look at a print with the light of the room falling on it. A slide is a piece of film, for the common 35 mm slide 24 by 36 millimetres in a mount of five by five centimetres, and the image only appears when light shines through it. Lay a slide on the table and photograph it, and you mostly see a small dark square. So you need light from behind. And because the image is so small, every speck of dust and every fingerprint shows up in the digital version.

Phone, slide scanner or a service

A phone and a light source get you started fastest, without buying anything. The result is good enough to view on a screen and share with family. If you have thousands of slides, a slide scanner is worth considering. It is a separate device you feed the slides into one by one, so every slide is captured at the same distance and with the same light. That saves aiming and cropping. A flatbed scanner with a transparency unit for slides and negatives works too.

You can also have slides digitised by a company that does it per slide. The originals do leave the house then. Count them first, note which box or tray holds what, and keep back the slides you value most until the first batch has come back safely.

How to do it with your phone

• Use a tablet or laptop as a light box: put a completely white image on the screen and turn the brightness all the way up. A real light box works too.
• Put a sheet of white printer paper or baking paper between the screen and the slide. Without it, the pixels of the screen show up in the photo as a fine grid.
• Work in a dark room and cover the light around the slide, for instance with a piece of cardboard with a cut-out the size of the mount. Light that reaches the camera past the slide makes the image look washed out.
• Blow dust away with a blower. Don't wipe the film with a cloth, and hold the slide by the mount only.
• Check that any text in the picture reads the right way round. If a street sign or a shop name appears in mirror writing, turn the slide over before you take the photo.
• Hold the phone straight above the slide, switch the flash off and tap the image to focus. If the camera won't focus that close, move back a little and crop the photo afterwards.

Scan mode in the Ohhi app

Scan mode in the Ohhi app is made for printed photos, but you can use it for slides as well. In the plus menu you choose 'Scan old photos'. The flash then stays off, a spirit level on screen shows whether you are holding the phone flat, and the camera stays open, so you can work through a whole tray in one go. Edge detection is tuned to a print lying on a table. With a slide on a light source it doesn't always find the right outline; in that case crop the image yourself in the editing screen until only the photo is left.

The same editing screen has a date button. Many slide mounts have a month and year printed on them. Fill that in, and the slide sits at 1978 in your library instead of at the day you digitised it. Some slides have turned red or purplish over the years; the warmth and saturation sliders take away part of that colour cast.

The date on the mount is usually the month the film was developed. The photos themselves were often taken a few weeks earlier.

What's written on the mount

Besides that date there is often something handwritten: a place, a name, a number. Copy it over before the slides go back into the box. In Ohhi you put it in the photo's caption. You can add a place yourself afterwards in the photo's info panel, and the slide then shows up on the map among your other photos from that spot.

Together with the family

A box of slides usually belongs to the whole family. Put the digital versions in a folder, say one per tray or per year, and invite brothers, sisters and parents to look along. Whoever was there often still knows where a photo was taken or who is standing next to grandpa, and can put that in a comment. How to share a folder is explained in sharing an album with family.

If the same box also holds prints, scan mode works for those as intended; see how to scan old printed photos with your phone. If you don't have Ohhi yet, you can create a free account and start with the first tray.