Cheaper, longer, but not faster. The Tamron 200-500 for wildlife

Cheaper, longer, but not faster.

Brief review of the Tamron 200-500mm lens for wildlife photography

At around $700-800, this is the cheapest lens that reaches 500mm, except for a few awful lenses (e.g. from Phoenix) that are little better than toys. On the affordability scale, the next step up is the Sigma 50-500mm lens, which generally runs $900-$1100, and after that, you will need thousands of dollars to get this focal length. The low price of the Tamron, combined with its reasonably good optical quality, make it a popular choice for wildlife hobbyists.

Anti-shake

Lenses this long are hard to handhold, but fortunately several camera brands (Minolta, Sony, Pentax) offer in-camera image stabilization. Using the now superseded Minolta 5D, I can get handheld shots in impressively low light, and the newer cameras are reputed to be even better. Here is a cardinal, shot handheld at 1/200 sec., 500mm, f/6.3, ISO 1600 in very poor light (a cloudy evening around 7pm).

As you can see, this photo needed enhancing in Photoshop, but without the Minolta's in-camera antishake, I wouldn't have gotten this shot at all.

Sharpness

I used to live in California, which has an unusual abundance of interesting and accessible wild animals. Unfortunately, they tend to keep a wary distance from people, making long sharp lenses quite important. In terms of sharpness, the Tamron is good, though not spectacular. At wide open aperture, it's somewhat soft at maximum zoom, and sharpens up noticeably as you stop down from f/6.3 to f/8. The next series of photos is a bit boring (a nail in a fence), but it shows how sharpness increases steadily as you stop down.

Because Minolta's in-camera sharpening is milder than Canon/Nikon cameras, I also sharpened each photo in Photoshop to bring out more detail (see bottom row for sharpened photos, top row for originals). It's interesting how much visible detail is rescued. At f/6.3, sharpening in Photoshop is essential to making the images even usable. By f/8, the images look OK even without processing, but still show considerably crisper detail after processing. I should emphasize that Canon, Nikon (and now Sony) cameras do more in-camera sharpening, so those cameras should produce images that are more usable right out of the box.

Ergonomics - an undocumented push-pull feature

This lens is a standard twist-zoom type, unlike the push-pull style of some Canon lenses. I happen to like the push-pull zoom, because it allows one to change focal lengths very quickly. So I was happy to see that the Tamron can be used as an ad-hoc push-pull zoom. Simply grab the front of the lens, and pull it to the desired length. This doesn't seem to hurt the lens, and is much faster than turning the barrel. I don't know if Tamron designed it this way on purpose, but it is very handy.

Autofocus

Unfortunately, this lens let me down somewhat in an unexpected area. When I first tried this lens, it tended to front-focus, relative to my Minolta lenses. The errors were noticeable, and most noticeable at wide-open aperture, where depth of field is shortest. Fortunately, the Minolta 5D has an undocumented ability to adjust the focus plane (via 3 hex screws underneath the sticker on the camera's bottom). A little tweaking brought the Tamron lens into perfect focus, but at the expense of my Minolta lenses.

Another issue is focus speed, which depends somewhat on the camera body. On the Minolta 5D, focus is decent, but not fast enough for more than the occasional flying bird. I find it much harder to capture flying birds than with Canon USM lenses of similar focal length. In particular, this lens focuses well if it is already focused near the correct distance, but with flying birds, it is easy to accidentally point the lens at the sky behind the bird. Because the blank sky lacks any details to "see", the camera immediately loses focus lock, and cycles through its entire range of focus distances. This takes up to 2 seconds, by which time the bird is often gone.

I should note that the Sony A100 is widely reported to focus faster than the Minolta cameras. Cameras with more focus points should also be better with flying wildlife.

Yet another focus issue is the lack of an autofocus limiter. With distant wildlife, there is no need to search the entire focus distance range, and the better wildlife lenses have a switch that limits the focus to distant objects. This greatly speeds up autofocus, but unfortunately the Tamron does not have this feature. That is quite a shame, as focus limiter technology is very cheap, and can double the speed of acquiring focus.

Comparison to Sigma 50-500mm

I briefly used the Sigma 50-500 lens last year, and though I don't have side-by-side comparisons of the two lenses, my impression is that it has similar sharpness at 500mm, but better contrast, and less purple fringing than the Tamron. The Sigma is almost twice as heavy, and somewhat wider in diameter. Both of these factors make it hard to handhold for long periods. Obviously, the Sigma also covers the 50-200mm focal range which the Tamron does not. This is surprisingly useful, especially when hiking outdoors in situations where it may be difficult to switch lenses.

Summary

This is a good lens considering its low price and long focal length, and it is especially useful when combined with in-camera antishake feature. However, on my camera (Minolta 5D) the focus speed is not fast enough for things that move quickly, like birds.

Visits to page:
Counter