I have been testing the efke 820c in 120 size and 35mm. At first with a 29 filter which produced nice black and white images but little or no IR effect. I then did some side by side comparisons before HIE dried up to see if it was necessary to stock up. The photos with 820c and an IR cutoff filter shots worked surprisingly well, but since i'm a compose-and-shoot-handheld kid o' guy, I stocked up. However i have started a new EFKE 820c body of work on things that don't stand still... windy trees, waves, waterfalls, etc. It seems it takes a lot to overexpose the film. I just recieved some 4x5 sheets from Freestyle, and i'm going to try some f11 at 30 second exposures to see how true that is. My verdict was that Efke with a 072 cutoff at ASA 1 can look very much like HIE thru a 25 filter at asa 200.