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The Tamron 17-50mm f/2.8 - In Depth
17 April 2008
So, I’m a bit late with my post this week - there’s perfectly good reason for that, I think. April 15th is my day of unending torture due to the wonders of the Infernal Revenue Service. But, it’s done and I’ve moved on.
I promised a better look at my two lens acquisitions this week, and so I’m starting with what I think is the better of the two - the Tamron 17-50mm f/2.8.
To be perfectly honest, I was nervous about spending a bit over $400 on a third-party lens, even if it was “free” money (I had earned about $600 in Amazon Gift Certificates from my bank). However, everywhere that I looked on the web turned out to be a favorable opinion of the lens.
Now I see why.
Let’s start with the build quality. The lens feels heavy for its size, and you’ll definitely find yourself supporting the camera correctly (by the lens) if you hadn’t done so while using the kit lens. It has a metal mount and a sturdy feel to it - it’s not like holding weatherproofed L-series lenses, but it will definitely stand up to the knocks and bumps that any amateur is likely to throw at it.
Also on the mechanical quality, one needs to be aware that this is not a USM lens - autofocus is a touch on the noisy side. However, this is not too obtrusive and it’s not really any louder than other non-USM lenses. In addition, the focus ring on the lens is not decoupled from the AF motor, so the ring moves in AF mode. The lens does not support Full-time Manual focusing, which is a pity, but a very minor complaint - flip the switch from AF to MF and get on with your life.
Even with these minor niggles, the lens is superb. Optical quality is spot on, with an incredibly crisp center and very nice corners as well. Surprisingly, despite the lens being made only for crop-body cameras, vignetting is pretty well non-existent. And chromatic aberrations? Nada. You will see a very tiny amount at 17mm @ f/2.8, but I feel this would be irrelevant in actual field usage.
There is one thing worth noting on the optical quality, and that’s a bit of a “bent” focal plane. I’ll try to take a picture that illustrates this clearly, but the field of focus is actually curved. This is natural for any lens, but there are tricks to work around it in the lens mechanic. On my copy, this is not too apparent, but you may notice that at low apertures (f/2.8, f/4) your subject is in focus in the center but something that’s actually behind your subject is in focus at the edges. Expect it to happen most when you’re close to your subject with a very shallow Depth of Field. This phenomenon disappears at about f/4.5 and above or when focused out far distances.
As odd as it is, it’s actually a godsend when shooting such wide apertures for portrait work and the like. Most lenses at f/2.8 can focus on the nose and eyes, for example, but the ear will then be out of focus. This curved focal plane fixes that problem, allowing the focus to “wrap around” the subject. So, just because it does something you wouldn’t expect doesn’t mean it does something bad - it’s just a little quirk to get used to.
So, is the lens worth its salt? In a couple words, “Hell yes.” At the price this lens costs, it’s an affordable trade for the kit lens. The build quality is great for the cost (far better than other Canon zooms in this price bracket) and the optical quality is superb. The extremely wide aperture makes for a very, very versatile lens that you’ll find sits on your camera a majority of the time. All of this for under $450 will leave you wondering why every lens can’t offer this much bang for the buck.
I’ve got a couple shots of the lens in action that I’m uploading right now, so you can see it in a few of its more useful moments - portraiture and landscape. To top that off, you can expect a full write-up on Friday about the Canon 55-250IS lens. Who said good things don’t come free?
Topics: Equipment, Photo Shoot |