There are plenty of reviews on the internet for this lens. These were some of the most useful ones for me:
I'm not going to try and compete with reviews that are already out there or do anything complex in this review... simply what is the lens like, what are its features and how have I found it so far when using it (in conjunction with a Canon EOS 70D body).
The lens is not small... it's nearly 2kg in weight! However it is nicely balanced at the tripod mount point when it has a camera attached. Long-standing Canon users might find the zoom and focus ring a bit hard to get used to at first. The focus ring is closer to the camera body (unlike most Canon lenses where the zoom ring is closer). The zoom ring also rotates in the opposite direction to Canon lenses. Fortunately I've not had a problem getting used to this as it's similar to the Fuji setup that I've been using for a while.
The lens comes equipped with VC (vibration control - their version of image stabilisation), a zoom ring lock, switch for manual/auto focus as well as a focus limiter switch which can be set to the full zoom range or 15m to infinity. It's also supplied with a lens hood and front/rear lens caps, but no kind of bag or pouch which would have been a nice touch. The lens does seem built to last with some sensible looking rubber gaskets giving weather/dust protection by the mount as well as inside the zoom mechanism.
Here are some photos showing the size and features of the lens:
Lens attached to EOS 70D with lens hood.
Zoomed to 600mm
Some of the lens features: Zoom ring on the left, manual focus ring on the right. Buttons from top to bottom are the focus limiter, manual/auto focus switch and then the image stabilisation.
Lens cap
The outer lens element is a whopping 95mm diameter!
Top view of the lens showing the zoom ring lock (very hand for when carrying such a heavy lens).
So what's it actually like to use? So far I have been very impressed. The focus speed has been great and the USD focus motor is extremely quiet - I haven't had many issues with it trying to find a lock even in darker conditions, but I haven't yet had a decent chance to test its bird-in-flight capabilities. One of the slightly strange things to get used to is that the VC kicks in when focussing for the first time so you get a slight 'bounce' of the image through the viewfinder. I have managed some decent hand-held shots, but you certainly get the best out of the lens when resting it on a tripod or bean bag for support. The zoom range is literally staggering. On the 70D due to its 1.6x crop factor, the range is effectively 240-920mm which gives amazing potential for wildlife. The only danger is that you can end up being too close to subjects!
Here is an idea of the zoom range available:
@ 150mm
@ 600mm
The lens is not what you would call a fast lens in terms of its maximum aperture, but with the great improvements in camera high ISO technology I have been finding it's not really an issue. In my opinion it's also very nice and sharp all the way to 600mm for all practical uses. The bokeh also seems to be really nice, helping subjects stand out nicely. Here are 2 examples showing the full picture as well as 100% crops of the same images.
600mm, F8.0, 1/640 sec, ISO800
600mm, F8.0, 1/2000 sec, ISO1600
So overall I'm really pleased with this lens so far. Its closest competitors are probably the Canon 100-400L and the Sigma 150-500. The Canon is more expensive, has much older image stabilisation technology and lacks 200mm in reach. From the image tests I have seen, the image quality between the Canon and the Tamron are very similar across their corresponding zoom ranges. The Sigma is similarly priced - probably slightly cheaper - but seems to have a lower image quality from 300mm upwards. The sharpness when compared to the Tamron at 500mm was something that for me sways totally in favour of the Tamron, not to mention the extra reach. Here are some useful links for sharpness comparison:
Sigma vs Tamron @ 500mm
Canon vs Tamron @ 400mm
Hopefully you'll find this helpful in seeing the Tamron in action
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