First: I love my GA645i and it's a fantastic camera, but just not made for IR film.
Not sure about GA645 but the GA645i has infrared film frame spacing sensor placed on a very bad position that exposes a visual stripe on IR-sensitive films, something you don't see on any "normal" films. Always wondered why the Fuji engineers found it so hard to place it to read the corner area of the film instead the center! :bang:
Here's some color infrared shots after which I will never put a IR film into GA645i again:
Java lady by
tsiklonaut, on Flickr
Gunung Agung by
tsiklonaut, on Flickr
Maybe the non-"i" is better in those terms?
Anyways, if you shoot let us know if it worked out!
On Efke Aura with 715nm filter I rate the ASA down to 1,5, yes, trust me I've tried it all, even rate it to ASA1 to be on a safe side for most standard developers (if you don't use film speed increasing developers - i.e. for Diafine I rate Efke IR820 to between ASA 3-6). Anything more than that create underexposure and IR-film is a very bad performer on recording shadows, obviously a tripod is a must. With IR focus on GA645 is impossible to have it spot on since it has no IR-focus like the manual focus lenses have a special marking for the IR-focus (depending on the focal lenght is a "front-focus", usually the longer the lens the nearer the IR focus is). With GA645 just stop down the lens a lot I guess.
Margus