You'll have to tell me about pushing C41 films. It seems to me that all that happens is some kind of gain in the base+fog.(posted 9007 days ago)I have test exposed XP2 at various speeds, all processed normal. At 800 it looks kind of normal with maybe some "grain" appearing in the dark areas of the print and shadow detail is going away a bit. At 1600 this is more pronounced and there is still nice detail though less sharp in fleshtone areas. At 3200 its pretty much not responding except to the brightest areas of the scene. I think 800 negatives would be printable in the darkroom. 1600 is questionable, probaly not to make a nice print. 3200 I think don't even try. For scanning 800 is quite fine, 1600 can be adjusted in levels in Photoshop to give a very lovely antique kind of look. 3200 and I guess you could use it to identify the robber that held up the drive-in market and thats about all.I think the clumpy grains that show up when XP2 is underexposed are the dye clouds that would overlap each other in normal exposures. I understand that the emulsion is "2 speeds" put together into one layer. This accounts for its wide exposure range and smooth gradations. Apparently, upon underexposure, we are seeing the result of one speed going off the toe of its curve, and no longer responding to light, while the other is still responding.
I usually rate this film at 320 and really like it there for all around use. If you want ultra fine grain and sharpness, try it at 200. I think this film is amazing in its ability to give good pictures under an incredible range of conditions.