Explain 70mm film to me thread...
If you bought what I think you bought, they're canisters and not a back. You also need a back that is compatible with whatever medium-format camera you have, into which you insert those canisters once they're loaded. Or you can shoot 6x7 on 70mm in a 4x5 camera using a Linhof Super-Rollex back.
While the film is wider than 120, the extra width is basically all taken up with sprocket holes so the image size will be the same as the normal image size of whatever camera you're using. The point of 70mm is that you get many many shots (at least 55 of 6x7, about 70 of 6x6) on a roll, not that the image is bigger, unless you're buying unperforated film (quite hard to find) and slitting/respooling to strange formats like 616, in which case you don't need these canisters and wouldn't be asking these questions... I believe the main market for this stuff was aerial photo mapping/reconnaissance and bulk portraiture.
As to price, I shoot mostly 2405 for about 1/3 to 1/4 the cost of a typical 120 roll. And it looks/behaves just like SFX200, which it's about 1/6 the price of here. Similarly for IR - have you seen the price of IR820 since its discontinuation? Then see the price of 70mm IR400 is about 1/2 the price of plain B&W film, even if its spectral sensitivity is not quite as good as IR820.
Developing 70mm is a real hassle; you can get a Nikor tank that will take 5m of it in one batch, but they're expensive and hard to find. Developing 70mm on Paterson (or Jobo) Reels - and I do that.
My homemade 70mm loader, or you can pay about $300 for the Auden 70mm loader if you can find one.
Last edited by polyglot; 12-16-2013 at 05:33 PM. Click to view previous post history.