Monday, July 2, 2012

Tamron SP AF 17-50mm f/2.8 XR Di II LD IF (Nikon) Lens Review

I think it says something about the basic usefulness of the Tamron 17-50 lens that I haven't as of yet gotten around to formally reviewing it. It's something that I've taken for granted for so long. There are some opinions out there that real pros don't use normal zoom lenses, and to be truthful, there is merit to that. If everybody else is using the normal zoom range, then how will your pictures be any different?

However, a more pragmatic approach is to look at what you need for a given situation, and if you aren't trying hard to come up with the one shot in a hundred that few others would produce, then normal zooms are eminently practical. The Tamron 17-50 covers 27mm to 75mm, full frame equivalent. Think about that for a minute. What are the basic primes that Leica shooters and film aficionados have in their collection? That's right, 24/28mm, 35mm, 50mm, and 90mm. So, that is to say, you can produce some very creative work in the normal zoom range, as pedestrian as if is. It's not stopping the guys with the Leica M9's, that's for sure.

That said, it is true that I find my self gravitating towards the extremes of this lens, mostly using the wide angle or at the long end. This is especially true if you are thinking hard about composition. There are other times when you just frame and twist the zoom ring.... there's no same in that. There is truth to the fact that the normal zoom range can be boring, but don't let that stop you.

 The Tamron 17-50 has a build quality that is in keeping with the D90, D7000 serious consumer range. It balances nicely on these cameras, and is small and fits well in your hand. By comparison, if you strap on Nikon's 17-55m AF-S, you'll feel as though you've just attached a bombshell pointed the wrong way onto your camera... it's that heavy and that big. You'll forget the Tamron is there. The Nikon won't let you forget. If you add a SB-600 flash, your biceps will be bigger by the end of the day. Not so with the, the Tamron 17-50, which is plastic, but it's no more plastic than the exterior of any mid-range camera. Compared to it's big brother the, the 28-75, there is far less barrel wobble, and the overall package feels a lot tighter. Nikon made the 17-55 to be  the best in this range.... Tamron merely made their lens to match the average enthusiast level dSLR.

Tamron 17-50 on Nikon D7000

Granville Island, Vancouver, B.C.

For a lens that is popular the world over, this is already quite an old design by modern standards. The desirable copies to look for are the AF-D type screw drive lenses. These focus much faster than the built in motor (BIM) lenses that followed. On a D80, D90 or D7000, focus speed is a non-issue, as the lens is geared relatively fast. As with most, if not all Tamrons, the focus ring moves during focus, but the lens is an internal focus design, so the lens length stays constant during focus. However, unlike the 28-75 AF-D version, manual focusing with the Tamron merely feels adequate. It's smooth and the focus ring is nice and substantial, unlike what you would get on a modern consumer Nikon, but it doesn't have that nice pseudo-fluid dampened feel that the 28-75 does. The petal hood is nice and deep, and like all Tamron hoods, clips on in reverse for easy storage. I would not call the petal hood particularly sturdy, though, as witnessed by the fact that many used copies of these lenses have long since lost their hoods.

Just a caveat before proceeding. Many people stepping up from kit lenses are looking for "fast glass" so that they don't have to use flash for indoor photography. This is a mistake. I can verify that for indoor settings, the combination of this lens and a D7000 at ISO 3200 or ISO6400 is very doable, but the results are nowhere near as good as with using a flash. f/2.8 lenses are not so much about shutter speed as they are about depth of field control. The kit Nikon 18-55 goes from f/3.5 to f/5.6... yes, that's excruciatingly slow at the long end, and with the Tamron 17-50, you would be able to shoot at shutter speeds 4x faster at the long end, or two stops difference. However, that's still probably not enough for really dark situations, and if you do try f/2.8 at ISO 3200, you might be underwhelmed with the results. Not disappointed, but merely underwhelmed. So what then, is the advantage of using 'fast glass'...? It's quality. Most lenses are sharpest two steps down from open. On the kit lens, that means you are at peak sharpness at f/8. With the Tamron, it's very sharp by f/4, and you have a nice fat sweet spot up to f11. Take the picture below... it was shot with just the popup flash, nothing fancy. I had to knock down the highlight portion of the tone curve in post processing, but it wasn't by as much as you would think.

As a reminder that Tamron lenses tend to produce warmer colour rendition than Nikon lenses, so you might have to be a little more careful with caucasian skin tones. As shown in previous posts (Bokeh, 3 Lenses), the Tamron, being a general purpose lens, isn't as good at portraits as the 50mm primes or some of the longer portrait zooms. There's a bit of focus breathing, so you get a smaller amount of magnification at distances less than infinity compared to the 50mm prime. Like many modern fast lenses that use aspherical elements, the bokeh can be on the harsh side. This becomes less of a problem if you are careful about what goes into your background. If you are shooting at things with lots of trees and branches in the background.... good luck. However, in social situations, it's fabulous, you can keep a bring a quality piece of glass along that won't intimidate your friends and family.

Granville Street Bridge

The wide end says 17mm, which is the equivalent of 26.5mm full frame. I'm not sure if that's really the case, as lens makers, particularly third party ones, are a bit parsimonious with precision when it comes to specs. However, it's more or less the same as most of the lenses that go to 17 or 18mm that I've used. Nowdays, we've got wider options, but for most situations, this is wide enough. Anything less than 16mm and it becomes difficult to create composition... the wider you go, the more the composition needs to be anchored into something. It's not just about 'fitting it all in'. And for those times when you do need to fit it all in, at least we live in the age of stitching. The above shot of the Granville Street bridge is a stitch. When you're doing a stich like this, you have to be careful with the distortion that the lens produces. You'll get some wavy horizons if you take too few shots at wide angle. Either do extra overlaps, or better yet, zoom  until the distortion is gone.

Granville Island Public Market

Chromatic aberration can be pronounced if you aren't careful, but you might not notice it you have any one of the newer Nikon bodies with automatic lateral chromatic aberration removal. Vignetting will be a little harder to remove, and is quite apparent wide open at f/2.8, but that is entirely a matter of taste. You'd be surprised how many published pictures have the characteristic dark corners. There is also a hefty bit of field curvature when shooting at the wide end. This is a weakness if you are shooting at flat objects, but not so much in most other real life situations. Almost all lenses suffer from this to varying degrees, and at this price point, you aren't going to get away from it.

Main Branch, Vancouver Public Library
 I would say that architecture is not this lens' strong suit, if only for the distortion that you get at wide angles. Note that in the picture to the left  I was able to get the scene horizontally level (the railing on the catwalk), but that the vertical glass wall is off. This isn't a specific knock on this lens, as virtually any wide angle lens in this situation would suffer from the same problem. Most of the distortion goes away by 24mm, and after 35mm the lens starts to pincushion slightly. Otherwise, for the same scene, you would  need a tilt-shift lens for this situation if you want nice straight lines. That or you would need to apply distortion control in post processing.

Downtown Vancouver as seen from Fairview Slopes.

Keep in mind that I don't do objective testing here (there are so many other sites that do it well anyway), but it is safe to say that resolution is fantastic. All lenses are better when mounted on tripods, and the Tamron  will produce incredibly tack sharp images past f/4 on a tripod, virtually indistinguishable from the best. Note in the picture above... it's actually one of my throwaways. If you look carefully at the cityscape above, there's a very important setting that you should always use for tripods that I forgot to turn on.

Prices range quite a bit on the used market. Around here you can find the screw-drive versions from $250 to $400CDN. There's no rhyme or reason, so take your time and make sure that you test any used copy before you buy. More expensive does not guarantee better in this case, so there are bargains to be had if you are vigilant. So long as there is no overt abuse, these lenses generally last as long as other lenses from this era... my bet is that the AF-D versions will probably outlive the BI versions, but it remains to be seen. Also be aware that the newer VC version of this lens costs a bit more, with used asking prices above $450CDN in Vancouver at the moment. The lens formula is different; in exchange for image stabilization, you lose a bit of corner sharpness and a bit of bite with the lens wide open. The classic version of the lens is very usable at f/2.8, the stabilized version is merely adequate. Though some would say otherwise, my opinion is that the stabilized version doesn't have the genius of usability that the classic does. The used market seems to agree; classic 17-50's, both screw drive and BIM versions, tend to buy and sell quickly. The VC versions seem to stay up on Craigslist for a longer period of time.

Another caveat: Those of you with the D300/ D300s or D7000 might have come across this already, but Nikon's AF fine-tune system doesn't play well with third party lenses. I'm not sure if this is the case for all lenses, but the camera will not assign discrete identities for your third party lenses, meaning that you have to remember the fine-tune value in your head instead of having it stored as separate entries in the camera. It's an inconvenience... my D7000 doesn't distinguish between my Tamron 7-50 and my Tokina 50-135, so it uses the same saved fine tune value for both. This is more of an annoyance than anything else, but don't hold your breath waiting for Nikon to fix this.

You my also be tempted to cross-shop this lens against the Nikon AF-S 16-85mm f/3-5-5.6G ED VR DX. It's more expensive on the used market, with prices  going for not less than $500CDN in my area. You gain vibration reduction. but you lose depth of field control. For me, it's not worth it. At 85mm and f/5.6, the Nikon isn't suited for throwing the background out of focus for portraits. However, if you must shoot flashless and at still subject matter, the Nikon will have an advantage for handheld shots. In the end, these are two different lenses aimed at two different users.

As you can tell, I like this lens quite a bit, but it's virtues are almost invisible after you've had i for a while. That's probably the mark of a product that has hit it's sweet spot... you shouldn't notice that it's there, and it should do its job so well as to be unobtrusive. I think that describes this lens quite well.

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