"Which leaves us back at DOF, and I ask again, with a 135mm lens especially, where will f5.6 succeed where f2.8 would fail? I know you said there is more DOF, I don't deny that, but as David also points out, with a 135mmm the main difference is how out of focus the out of focus elements are going to be. You're not going to get a lot sharp by stopping down to f5.6. "
The IS lens will be much better at getting more DOF at the 135mm end, which is my concern. What David thinks is the main difference is not my concern as I am not interested in out of focus stuff.
"Right.... so I take it you wouldn't buy/own/use a 600/5.6 or even a 300/4 for the same reason, unless it had IS? "
Yup. will not buy them unless I plan on using the tripod.
"What did photographers do last time when high speed emulsions were not even as good as they are today, and they had to use 200mm f5.6 lenses? Stop taking pictures?"
My dear sir, u know the answer is obvious. They will have to resort to tripods. I dun use the tripod and so I will not use the 200 f 5.6 lens. simple ?
"It just seems as if you want to be able to hand hold a lens all the time. If you can ask why you would want IS on a wide-angle, yet covet it on a 135mm, then your concern is really not DOF at all, just that you don't need to use a tripod. If so, then say so."
Dear Jed, let's not get so worked up and start jumping into conclusion and putting words into people's mouth. yes, i do not wanna use the tripod and I am also interested in getting good DOF , which the IS does a good job at the longer end. For hand held photography, I am happy to get DOF of f 16 or so, which I find is difficult when using non IS lens during dim light which incidentally happens always to coincide with the sweet light timing.