I have often read that HP5 pushes nicely to ISO1600 so I thought that I'd give it a try. I bought a brick of HP5 and had a roll in my camera for experimenting. Last night while out walking, I shot about 6 shots or so in very low light. Sadly, I can't recall the shutter speeds needed but they were 1/30th at least if not a bit faster. My lens is f/3.5. Then today, I shot the last 4 images on that roll in much higher light, but still somewhat low as they were indoor shots. Then, I souped up the roll in HC-110 @ 20 C, dilution B, for 11 minutes. The film is hanging in my shower now and looking at the negatives I see many frames with virtually nothing in them. There is a bit of the subject, but huge swaths of empty negative, clear as day. It's too early to make any firm conclusion until I get the scans back but my initial impression is that this experiment did not work. If the scans look as bad as the negatives, then it would seem to me that I cannot use HP5 at ISO1600 in low light. Perhaps I was not paying attention. Would pushing HP5 to ISO1600 be for higher shutter speeds in moderate light? Is that what most people are doing when they push this film? Oh by the way, the last 4 shots on the roll came out excellent. These shots were the ones done today in-doors in much better light. So I am confident that my developing was fine. Thanks for any feedback!