When it comes to digitising old collections of slides and photographs, there is a vast choice of equipment available or specialised scanning services who will do the job for you. In this article we explore the basics of resolution, the key differentiation in your choice of equipment when converting slides and transparencies to a digital format.
Before you start digitising your collection, make sure you have followed the instructions on cleaning your slides. Dust and dirt barely visible to the naked eye on a slide will be magnified and very noticeable on the digitised version as resolution will magnify the image from its original size.
The choice of equipment available these days is vast and for the backup of a family archive is very affordable. All scanners will be made up of a back-light and digital image capture technology, but some will have higher resolution than others, and generally that will be reflected in the price tag. Choose a scanner that suits your budget and requirements.
A typical home printer will use a setting of 300 or 600 dpi (dots per inch) to print an image and a rough rule of thumb is scanning at 300 dpi will allow around the same size of print as the original photograph or at 600 dpi around 80% larger than the original.
The challenge with scanning from slides is the small size of the original image. So resolution of the image capture technology is key to determining the size of the output image. Professional scanning services will tend to scan slides at 3000-4000 dpi, enabling a print output of 8" x 10" print. However, If you're only intending to access your digitised image on a screen, capturing in high resolution is less important and a basic slide scanner will suffice as screen resolutions are typically an equivalent of only 72 dpi (though some are higher and the dots are actually pixels).
If you add images to the The Arkive, we will resize the image to be shown to a maximum width of 600 pixels. The higher the resolution of the viewing screen, the more pixels it has - effectively smaller pixels allowing a finer-grain in its display - so our 600 pixel-wide images will appear smaller on a high resolution TV than on a laptop screen. We limit the size of the images though to optimise the loading times and storage size of the images for smaller screens as most of our views are on mobile devices. And it's how you intend to view your images in the future, which is the key to how much you may want to invest into the digitisation process.