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. Thanks.