Hey guys, sorry I've been busy at work all day and the "notify me of replies" feature only seems to work sometimes (and in this case, not at all). So, by black glass I was referring to a very dark ND filter, in this case its not technically glass, but rather a gel. I'm using a 4.0 and I think that equates to 14 stops, and then I'm using f16-22 and iso 50-400, depending on the scene. Like I said at 50iso and f22, I think I could push a 20min exp no problem (and maybe even 40min, as that would only be 1 stop brighter than 20min). As for f22 degrading IQ, I wouldn't worry about it, your not going to get great IQ, no matter what you do, on a 5+ minute exposure (camera shake, movement, changing light, light refraction, wind ect), its more about the effect than the IQ. As for hot pixels, you definitely get quite a few, and I suppose I could use a subtraction image, but I'm too impatient, so I just deal with them in post. No HDR in these, as I obviously didn't need it, one thing I've found is that the DR in these super long exposures is incredible, I haven't figured out why from a physics stand point (to be honest I haven't even looked into it yet), but I'm sure there is a reason. I have plans to shoot a few locations with long exposures like these that would have enough DR to necessitate HDR, which I'd be more than happy to post. I'd love to see some of the stuff you guys have come up with using similar techniques...
