Originally posted by reh321 I would probably never use the f/2.8-4 part of a 70-200mm f/2.8 lens, so the f/4 variant makes more sense to me anyway ..... but since I'm not a "FF'" user, Pentax probably isn't interested in my opinion. If they were to ask me, however, the f/4 variant makes sense purely because of the savings, savings in $$$, and savings in weight.
I have the Tamron version 70-200 f2.8, and I can say that on FF that FL with F2.8 is really an indoor wedding lens. Carry 2 bodies, put a 24-70 or 28-75 on the other one, and never have to change a lens the whole day.
It pains me to admit, but it drives me a little crazy when people say they will never use the F2.8...
F2.8 isn't just there for shooting with at that set Fstop, it is also the brightness you see in your viewfinder before you trip the shutter, because the lens only stops down to what you set it to when you take the photo... it is also what the F2.8 cross type AF points see, so you get faster AF, more accurate AF, and better low light AF, . So to say you will never use it is a totally wrong, because you are actually using the F2.8 advantage ALL THE TIME.
(Don't mind me, just trying to help people enhance their LBA)
Eric