I just finished converting a Polaroid 800 to use 120 roll film for about $5.00 of materials purchased at the local hardware store. Due to the camera's decent lens, very accurate and easy-to-use rangefinder, and the large negative size, you can get some excellent results with this conversion. The camera is built like a tank, making this conversion easy to do. The only tools I used include a power drill to make one 1/8" hole and a pair of scissors. I use Shanghai GP3 120 b/w film, which I get at less than $3 per roll and I process b/w at home at very little cost.

Exposure on the camera is controlled with one dial for EV (Exposure Value - GOOGLE it if you don't know what EV represents). Using ISO100 film, you can use the exposure value dial on the camera directly to get proper exposure. If you want to do some math, you could use other ISO speed films. I get about 6 (maybe 7) pictures on a roll of 120, with no cropping, producing a negative that is 4" wide. That's a big negative. If I use a mask, I could get narrower negatives and more shots per roll.

I have read that others have used this camera to shoot on 4x5 sheet film. If a person is willing to shoot one sheet at a time and then use a changing bag to remove the sheet, no "conversion" work is actually necessary to use sheet film in a Polaroid 800. I have some Shanghai 4x5 black and white sheet film in the freezer which I will try.

The Polaroid 800 was built from 1957 to 1962. As I said, these cameras are built like tanks. Your chances of picking one up on Ebay for $50 or less are very good. Just make sure to ask the seller about the condition of the bellows - usually if the bellows are not in good shape, the seller will not show a picture of that part of the camera on Ebay.