Originally posted by sriram
The 100/2.8USM (one in this pic) allows a tripod collar to be attached. You have to purchase it separately, and the collar is hard to get in Singapore. The old 100/2.8 non-USM did NOT have a tripod collar. Still, I haven't purchased a collar for my 100/2.8 because it cannot be used with a battery pack / booster- the collar is so close to the lens mount that it hits the battery pack. The lens itself weighs only 5xx grams, Coupled to something like an EOS-3 and booster (12xx-13xx grams) it makes more sense to support the camera.
Even in this picture, it makes more sense to support the camera. The D30 and two extension tubes would weight a lot more than the lens alone. Ideally, this guy should support both the camera and the lens since he's using so many tubes.