Recently I stumbled across some very rare mammals - nocturnal, of course, almost all marsupials ae nocturnal - and wanted to take their picture. I had no problem getting close enough, and astonishingly enough, no real problem with flash - they weren't fazed at all by it - but focusing was very hard.
Autofocus really struggles when the light is very bad - I'm talking a couple of hours after sunset here - but manual focus is difficult enough with a digital SLR (they don't have visual focus aids anymore); more difficult with a long lens; more difficult again in bad light; and still worse when the creature is moving around.
In the end, I got the shots, some using autofocus where the creature stayed fairly still for long enough, others with guessed-at manual focus, and others again by pre-focusing on a particular spot and waiting till my quarry passed over it. All in all, it was a very unsatisfactory way of going about things. There has to be a better way. Any hints?