I've lately been experimenting with redscaling film. My process is to unwind the film in the darkroom, cut and reverse the film, then rewind it. This works great with my fixed focus, fixed everything point-and-shoot cameras -- for example the Vivitar Ultra Wide & Slim that has a fixed shutter speed of 1/80 or so. If I use 800 speed film in bright sun, the exposure is right on (as these things go).
Lately I tried this in my Olympus XA4 using Fujifilm Superia 1600. I set the camera ISO to 400, wanting to "overexpose" by two stops. The resulting negative was dark -- very dark. Next I tried setting the ISO to 50. The resulting negative was just as dark! Either the meter in the XA4 is bad (which hasn't been my experience when shooting film "properly") or something else is going on. Could the XA4 be compensating for the increased exposure by opening the aperture instead of increasing the shutter speed? This is conjecture. I'm thinking now that redscaling responds more to duration of the exposure than the intensity of the light, but I'm appealing to those more experienced than I for expertise.
This is a total S.W.A.G., but perhaps the Fuji film has a different anti-halation coating under the emulsion that effectively filters out much more of the light than other types of films. Have you done redscaling with any other Fuji film?
Thanks Joe. I've redscaled this exact same film with good results. The camera I used was a point-and-shoot type with a fixed shutter speed of 1/80 to 1/100. I've used slower film (Fujifim Superia 800) in a pinhole camera and have also gotten exceptable results.
bryant park by bvybvy, on Flickr
Really scratching my head...
Just a guess, but is the film canister coded? If so - and if you didn't cover the contacts in the camera - its probably ignoring the iso you set and using the auto detected value.
Maybe it's reading DX code from the film case and overriding your ISO setting?
EDIT: Brian types faster ;-)
Okay, I feel like a fool. Sure enough, there are DX contacts inside the camera where the film sits. What, then, is the ISO dial outside the camera for? Part of my confusion is that I upgraded from the XA2 which has no DX capability, and the same dial must be used to set the film speed.