Scanner adaptations.

 The Canon 8800f originally came boxed with accessory fixtures for scanning films of different types.

I didn't want to spend $50 on eBay if I do without, so I developed workarounds. Scanners have CCDs that act like cameras. And like cameras, they have a focal length. Theirs is fixed. I read an interesting article on testing the focal length of scanners. That article gave me an idea. I got a piece of window pane glass and cut the glass to fit on the scanner glass bed, referred to as the 'Platen.'

I did some test scans of old ruined negative film that had highly detailed, sharp etch marks that woiuld work as an indicator of level of detail. The window pane was placed on the platen and scans made at high resolution. The pane was removed and a similar set of scans made. The two sets were examined in the sharply deailed damage area of the film negative. The detail was clearer on the platen than on the pane.

The glass window pane was kept as a way to insure the images were flat on the platen, and not curled or bowed. This worked because the scanner lid is removable and raisable for things like books.

This issue came up when I considered the design of the accessories made by the company. Only the slides seemed to rest directly on the platen, all others film types were raised by their respective plastic tools. For this reason, I thought laying film directly on the platen may result in out-of-focus images. I was wrong. The depth of field for the CCD woiuld likely include the platen surface since documents would be placed directly on the platen. The doubt came from the software which has a 'Film' setting. 

Whatever the details, placing film directly on the platen works. Flattening film with the glass pane works.

I drew indicator lines on the platen to aid in the placement of film. That was very helpful.