A Camera is the machine used to record the image, moving or static. Traditionally this was onto a film. Now it is can also be recorded digitally. Mixing the traditional; Analogue with Digital has lead to many interesting ways of presenting the final image.
It is necessary though for the negative image to be processed to become a print. Initially with large negatives this was placed in contact with photo sensitive paper and a contact print made. For smaller negatives the image was projected onto the paper using an enlarger.
While these techniques are still used many of us analogue picture takers turn to modern technology and create a digital image from the negative, or positive slide.
There are two pracitcal ways to do this.
One is to use a flat bed scanner and ensure there is a lightsource behind the negative or slide. The other is to back light the negative or slide and and take a digital picture with a digital camera.
Small basic 'scanners' on sale are actually just fixed position digital cameras in a box. For general domestic use, and quick scans they are fine. A more sophisiticated approach is to use a good quality digital camera, mount it on a copy stand and use it to photograph the negative or slide. with godd cameras and a good set up and specialist close up lens excellent results can be obtained.
Variations of the flat bed scanner are used in high end film scanners. There are also a few flat bed scanners that have a built in back light to enable transparency scanning.