Here's a question. Can you push Acros 100 five stops?
I'd picked up my Mamiya M645 1000s after a few months and saw I'd just started a roll of Ilford Delta 3200. So I did some indoor shots, including a vege market and a museum, and because I'd taken my time and each shot was carefully considered I thought there'd be a few keepers. Imagine my surprise when I opened up the camera and discovered, instead of Delta 3200, a roll of Acros 100. I'm usually so conscientious about exchanging the box ends so I'd know what I was shooting. But not this time. I was just going to throw the roll away but then I thought it might be an interesting experiment to see how far I could push it. These examples are after 20 minutes of ilford ilfotec lc 29 at 1/19. It's not too bad but not something I'd try again.
What's interesting is the only shots which were worthwhile keeping were those at the long exposure end. In this case 1/125, 2.8. Anything faster barely registered on the negative. There was nothing to push.