So F4 IS is better than Sigma F2.8 OS is better than F4 non IS? True or false please.
Neither, because the order is different considering which dimension (max. aperture, sharpness, bokeh, weight, bulk, price, IS (shutter speed). Unless you make up your mind and tell us what you want to shoot and what your preferences are asking such a question won't get you valid answers.
And not only that I asked about a different lens on my second post from on my first post! D'oh I threw in the F4 non IS and meant the F2.8 non IS.
I'm price limited, I'm also pondering trying for a 5D mk1 in the not too distant future (birthday wih list) as I keep hearing how much better FF is than crop. These pro workhorses seem to be going quite cheaply on eBay, seems like a way to dip a toe in full frame!
I guess I would list priorities as IQ (is that sharpness & bokeh) and fitting my used cost budget, I think my skill level may limit me to not needing the extra thin DOF of the 2.8 for low light!?
Main use probably motor racing and anything else that seems to want the 70-200 range.