Canon 28-105 f3.5/4.5 Mk1 or Mk2
Actually, the mark I was two versions. The early one with 5 blade aperture and the later one with 7 blades. They also differed in that one had a flower painted at the close focus setting and the ohter had "MACRO" painted there. Can't remember which was which. Then the mark II version came out with a new look but the same 7 blades. Optics were the same on alll versions. They are all a decent lens for the money.
And as Adam said, don't confuse this with the 4.5-5.6 version. That one has completely different and inferior optics with either a micro motor or micro USM focusing motor that isn't nearly as fast or sure as the ring type USM focus for the 3.5-4.5 versions.
Adam Clark wrote:
As far as I know, there is no advantage to the older model. In
fact, the Mk I uses only 5 aperature blades which can result in
unpleasant pentagonal bokeh. I believe the Mk II has 7 (or more)
aperature blades, and as such, the out-of-focus areas of its images
tend to be more appealing.
Just make sure you dont accidently purchase the newer 4.5-5.6 model
which has plasticky construction and no ring-usm motor.
Looking for a used copy of this lens. Is there any advantage in
buying a Mk1 rather than the newer Mk2?