Posted 14 May 2013 - 12:37 PM
I only recently received mine and although I've not taken anything "pretty" yet, I've conducted a number of tests with both my Canon 18-55 zoom and my 300 f/4. I can manage 2-3 min sub-exposures with the 300mm as long as I shoot in live-mode so the mirror stays up. The mirror-flop became an issue with 5 lbs 2 oz on the ball-head. After 3 minutes, I see the effects of PE, but I never really expected to go that long with that lens, so I'm quite pleased.
Because of my sky conditions where I am testing, I've not gone longer than 5 minutes at 55mm, but I've taken as much as 5 min worth of exposures at 55mm and stacked them in Photoshop without aligning and they look pretty good to me. At 18mm, I'd image I could go 30 min without needing to align, but of course, I'd be doing that in 3-5 min subs. At least in my camera (Canon Rebel T3i), I think dark-current becomes an issue after 5 min.
For anything serious, I plan to induce dithering to deal deal with noise and turn off the drive for 5 secs between subs. Then, I'll need to buy CCDStack to stack and register, but I have to say, I'm very pleased with the drive performance for what this is (and what it cost).
I have a dark sky trip planned for memorial day weekend and I plan to shoot a lot.