In a previous blog entry regarding this lens I promised an update. Now it's time to deliver. I've held off writing this because I'm so conflicted. The lens sometimes delivers such good results that I keep hoping that I'll find a way to overcome the issues I've got with it. In a nut shell this is my take on the lens: I know it can do great things - but not as often is I'd like, in the taxing environments and subjects I shoot.
I love wildlife photography, and wanted a long lens that would let me move into bird photography, and shoot basking reptiles and mammals without disturbing them. However birds are small, often very small, and constantly on the move: fast. Also, they are often in partial light or low light as in forests or other plant cover. This places a lot of demands on a lens. It needs to have the greatest focal length, largest aperture, best autofocus (AF), and highest image quality (IQ) possible. There are other important considerations that don't directly impact on the image or optic quality: price, size, and weight. All these considerations go into the mix and compromise must be made.
First let's address the things the Tamron does well:
The focal length of the 150-600mm is simply wonderful. The zoom capability is incredibly versatile, and the maximum focal length (600mm) is what I find myself using for birding 90% of the time. I'm still working at getting closer to the birds I'm shooting, but I certainly wouldn't want to give up 600mm, and in fact I'm very seriously considering getting the new 7D crop body which would make it 1.6 times longer.
Both the size and weight of the lens are very good. I can hand hold this lens for long periods, in fact so far it's the only way I use it (apart from occasionally resting it on a convenient branch or fence). It's still a big lens, and I certainly notice how much heavier it is when I switch back to my 150mm macro, but in comparison to all the other lenses in similar focal ranges, it shines.
The lens is capable of very good IQ. Even at 600mm I get images where I'm excited to see the first time I review them on a big screen. I'm really picky with image quality - especially with birds. You want to see the detail in the feathers since they are most defining feature. I know the lens is capable of producing wonderfully good IQ, but it doesn't do that nearly often enough in the situations I shoot in, which brings us to...
Price. Tamron owns the market in super telephotos with this lens. There is simply no competition at the moment - though Sigma has just announced two competing products.
Things the Tamron is not so good at:
Autofocus. It's by far the weakest feature of this lens. I think if I were shooting sports or something other than tiny, fast animals it would be fine, however I'd be lying if I didn't say I'm pretty disappointed with the AF. It's simply not fast enough, not accurate enough, and it wanders. I can take a burst of say 13 shots with AI Servo and you can see the focus wander from shot to shot. The result is that I have to spend a lot of time culling photos where the AF is out, and too often I've got shots where the AF has missed, but everything else was just magical. It's heartbreaking. More on this at the end.
Things about the Tamron that just "are" (neither good nor bad):
Aperture. The maximum aperture of the lens is f5 through f6.3 (depending on focal length). Since I shoot at the long end of the focal range, I generally get maximum aperture of f6.3, so by the time I stop it down a bit to help IQ, I'm looking at f8 or smaller. Obviously I wish it were closer to the f4 of the big primes, but that comes with a cost in size, weight, price and price (not a typo).
Where does that leave me with this lens? I honestly don't know.
I really, really want to like it. It's got heaps going for it and I think for anything but birding it would be great. Bugger.
I went to the trouble to send in to the Tamron workshop in Peth in the hope that a new firmware version I'd heard about online would fix the AF issues. Unfortunately all I got back was a confirmation that the lens already had the latest firmware, and was behaving as expected.
I've come to the point where I'll be keeping an eye on reviews when the new Sigma models hit the market. The "sports" model is supposed to have faster AF, but it's nearly twice the weight and price of the Tamron. The only other alternative is a big prime, and even second-hand they're very, very expensive.
Until then, I'll keep shooting with the Tamron, working on technique and looking at tweaking the AF in the hope that I can get better keeper rates. It does deliver some stunning shots.... I just wish I got results like this with it more often, could so you some of the potentially amazing shots where the AF missed.