I was going to tack this onto Arthurs thread but thought it was better in a thread of it's own so as not to get lost.
Tamron SP AF70-200mm F/2.8 Di LD (IF) Macro - Canon Mount
Lets start with the technical stuff - Thanks to Mr Tamron
Lens Construction (Groups/Elements) 13/18
Angle of View ( )=the figures when used on APS-C sized digital camera
Diagonal 34°21'-12°21' (22°33'-7°59')
Horizontal 28°51'-10°17' (18°49'-6°38')
Vertical 19°16'-6°31' (12°22'-4°15')
Diaphragm Blade Number 9
Minimum Aperture F/32
Minimum Focus Distance 37.4in.(0.95m) throughout the range
Macro Magnification Ratio 1:3.1 (at f=200mm, MFD: 0.95m)
Filter Diameter ø77
Weight 40.6oz (1150g) (without tripod mount)
Diameter x Length ø3.5 x 7.6in. (ø89.5 x 194.3mm)
Accessory - Flower-shaped Lens hood & case
Mount Canon -Available Built-In Motor
Nikon with Built-In Motor - Available
Pentax - Available
Sony - Available
I purchased this lens online from http://camerastore.com.au for a very reasonable price and the lens arrived on Monday 23 Feb 09, it came very well packed and basically overnight - enough of that this is about the lens.
Weight - Didn't feel too heavy but didn't feel overly light either
Build Quality :- First impressions were that this lens is built very well, there is no play in the focus ring or zoom ring and the Lens hood, bayonet type, fits very firmly with a positive click to confirm that it has locked in properly.
The main body of the lens I think would be of a plastic material though appears very tough and hard.
AF :- Numerous web reviews would have you believe that the micro motor used by Tamron is "very noisy" - All I can say is Bunkum, yes it is louder than either Canons USM or Sigma's HSM systems but then you would hope that it was.
AF Speed :- This one seems to be one point many reviewers labour over, my real world use would suggest that again it is probably slower than my 17-85 USM in actual "speed" but it is far from slow in terms of real life usability.
AF Accuracy :- Well doesn't this lens cop a caning in this department from the reviewers, 6 out of 10 failure rate, thats right just 4 in focus shots out of 10 according to some reviews. And the conclusion that this lens would not even be suitable to use when following children around the back yard.
I had the opportunity to utilise thios lens at an outrigger canoe regatta this weekend (feb 28) and I cannot complain about the focus accuracy or tracking ability one little bit. Did I have shots that focus was missed on, certainly did, was this a result of the lens, a couple of times I would probably say yes, but by far I missed more shots due to poor technique and unfavourable conditions, balanced precariously on a rock wall, than from the lens missing focus.
A series with the boat quatering away from me
Paddlers going across my view
Most of the talk surrounding this lens has been about whether it would be any good as a sports lens so I have concentrated on those issues here.
Summary (I know about time)
This lens appears well made, is quick to focus and tracks acceptably, the image quality is on a par with any (yes any)lens in this class.
Would I suggest this lens to the professional who absolutely MUST get THE shot each and every time, probably not but I would have absolutely NO hesitation in suggesting this lens to any one who like myself is after an admirable performer at the budget end of the scale
Having read numerous online reviews of this lens I was very hesitant about whether the AF was going to be worth the gamble of laying down any hard earned on this lens after this last week end I have no worries any more