I've never done long exposures (30 seconds and more) with my 1DmkII until the other night when I shot some sunset scenes in HDR. I used aperture priority and a bracket of 5 pictures, 1 2/3 stops apart. As the light levels dropped, of course, my exposures became longer until 30 seconds was reached on the 4th exposure of each sequence. After several sequences I noticed that the 4th and 5th exposures in the bracket were both 30 seconds and it took a while for me to remember that 30 seconds was the longest exposure I could get without using the "Bulb" setting.
I have been using the RS80N3 remote switch, but never went beyond 30 seconds before. Today I bought the TC80N3 thinking that I could use it to program a set of increasing exposure times and set the camera on bulb, but I can't figure out how to do that (or if it is possible with this remote timer switch.)
So far all I have come up with is setting the long exposure for, say 5" for the first shot, shooting, then setting the timer for 10", shooting, and repeating for 20", 40" and 60". However, this seems like a really klunky way of doing an HDR sequence.
I had hoped to be able to set the timer up to accomplish an automatic sequence of shots but I'm not sure now that it will do this. Am I incorrect in that assumption? And if so, I would like to return this remote and find out if there is a more sophisticated timer that will let me run a long-exposure bracket of 5 shots>