bluebomberx wrote in post #4583467
By the way, I can't comment on the sharpness, but Canon's documentation says it has a five-bladed aperture. The EF 28-105 f/3.5-f/4.5 USM II has seven. It will produce nicer bokeh and give silent USM operation with full-time manual focus. The lens you mentioned is driven by an AF-D motor that will be pretty noisy. Unless it's an insanely cheap price, I'd look for a second hand EF 28-105 f/3.5-f/4.5 USM II.
Usually they sell for less than $100.00. B&H has the mark II in stock for $74 and about $20 for the hood. There is a mark I for sale locally. With AFD focusing it is going to be noisy, I know that. If the aperture is fully open, the number of blades won't affect the bokeh. There are other factors that effect bokeh anyway such as the use of aspherics.
The Canon Museum only shows a small change between them (size, weight) but doesn't describe the reason for the update. Photozone gives the mark II a very good review.
I was hoping that maybe someone here has had these and could shed some light on if the mark I is also as good. Did Canon only change the cosmetics a little, or was is more. Since they look almost identical, I suspect it is a bigger change.
I already have a 28-135mm f/3.5-5.6 but this one looks to be quite a bit smaller and lighter. The 28-70 is only slightly faster in aperture since the 28-135 is f/4.5 from 48-60mm and f/5 from 61-80mm so that isn't very important. The 28-70 might be quite a bit sharper from the MTF ratings but in practice that might be lost due to camera shake since it is not IS. Mostly it is light and small and reputed to be very good.
Since it is less than $100 to risk, perhaps I should just buy it but I hate to do this twice.