tcchou71's Full Review: SanDisk Cruzer® (1 GB) USB 2.0 Flash Drive (S...
Update:
I recently traded the Canon version of this lens for the Minolta. The Minolta's anti-shake greatly improves handheld performance, though autofocus speed is about the same. The Epinions search engine doesn't seem to find the Minolta version of this lens, but you can get to it from this link:
http://www.epinions.com/Tamron_SP_AF200_500mm_F5_6_3_Di_LD_for_Maxxum_Telephoto_Zoom_Lens
You can also see photos I took with the Minolta version here:
(The optics are identical between the two lenses, but Canon cameras do more in-camera sharpening than Minolta, so the Minolta photos will initially look a bit soft.)
Lightweight, long, and sharp, but focus is only so-so
This was almost the perfect wildlife lens. It is surprisingly sharp, lightweight, and hand-holdable for sunlit subjects. Though it had somewhat less contrast, less sharpness, and more purple fringing than the Sigma 50-500 and Canon 100-400, the differences were not huge, and were correctable in Photoshop. This lens is lighter and cheaper than either the Sigma 50-500 or Canon 100-400 IS. And of course, 500mm reach is awesome, and much cheaper than Canon's 500mm f/4 lens, which costs $5000.
The three main drawbacks of this lens are (1) autofocus speed, which isn't good enough for flying birds when used on the Rebel XT, (2) lack of image stabilization, which makes handholding hard in low light, and (3) the need to increase contrast in Photoshop for optimum results. So that's this lens in a nutshell. For more details, keep reading:
The good points:
500mm
500mm doesn't sound like much more than 400mm, but when I compared the Tamron and Canon 100-400L at maximum zoom, the Tamron clearly resolved more detail than the Canon. This is helpful for objects that are really small and distant, like wildlife.
Light weight
The Tamron is only slightly lighter than the Canon 100-400, but feels disproportionately easier to carry and use, due to the Tamron's smaller barrel diameter, which makes it easier to hold.
Pumpable zoom:
I like the Canon 100-400L's pump zoom, because of how fast I can change focal lengths. But at the same time, I'm annoyed by the pump zoom's ring-tightening mechanism, which requires two hands to operate. So I was pleasantly surprised to discover that the Tamron is one of those rare lenses that can be used as an ad-hoc push-pull lens. The front of the lens is can be yanked in and out much faster than you can twist the zoom barrel. The motion is surprisingly smooth, and free of major resistance.
The bad points:
Focus accuracy
Although compatibility is always a potential issue with non-Canon lenses, this Tamron focused reasonably well on my rebel XT. However, I did find a higher proportion of misfocused shots with this lens than the Canon 100-400. One reason may be the maximum aperture of only f/6.3 at 500mm. I did not count systematically, but my feeling is that about 10-20% of all shots with the Tamron were misfocused, versus maybe 5-10% for the Canon.
Not image stabilized.
It's widely recognized that the lack of image stabilization in this lens makes it harder to handhold than the Canon 100-400L. However, by pushing the ISO up to 400, I was able to get consistently good handheld shots at 500mm for sunlit objects. It helps that the lens is OK wide open, though it's also noticeably better at f/8 than f/6.3. Under cloudy conditions, or for shaded subjects, I could only get sharp results by pushing the ISO up to 800 or 1600, where things are a bit noisy, though acceptable if you use NeatImage or some other noise reduction software.
If you really want to handhold this lens, you should instead get the Minolta version and combine it with Minolta's built-in anti-shake. That is the route I eventually went for, and it works well. You can see my thoughts on that combo here:
Incidentally, Epinions' search engine does not find the Minolta/Tamron review I wrote above. Until they fix this, you HAVE to use the above link to get there. Strange.
Lack of focus limiter makes bird photography difficult on the Rebel XT.
The most bothersome thing about this lens was something I didn't even consider when I bought it: the lack of an autofocus limiter. The Tamron's focus motor takes about 1.5 seconds to go from nearest to farthest focus distance, or about 3 seconds for a round trip. This is only slightly slower than Canon's 100-400L (which takes about 2 seconds per round trip). However, the Canon lens has a focus limiter that cuts the round trip time in half for distant objects. This is essential for subjects like birds flying against sky, which can disappear entirely in the time it takes the lens to focus. And because flying birds are hard to track, it's easy to point the lens at the sky behind the bird, causing the lens to lose focus. The Tamron lens will take 3 seconds to recover, by which time the bird will be gone.
My autofocus experience applies to the Canon rebel 300D and XT. Obviously, autofocus speed is also dependent on the camera body. Better cameras with more focus points will track moving objects better, but the Canon rebel models don't fall into this category.
I don't do any aviation photography, but the focus limiter would probably have been helpful for that too.
I had to use manual focus whenever I wanted to capture flying birds, whereas the Canon 100-400's autofocus was able to handle those subjects easily. Unfortunately, manual focus is not easy on most digital SLRs.
The mixed:
Optics
This lens has more optical flaws than the Sigma 50-500 and Canon 100-400. Its sharpness is on par with those other two lenses, i.e. it is OK wide open, but noticeably better at f/8. However, the Tamron has a tendency toward slightly low contrast, and high levels of purple fringing when used wide open. Both of these are correctable in Photoshop, though if you don't want to have to do the corrections, you may be better off with a Sigma 50-500 or Canon 100-400L.
Purple fringing is removable with the free "PFree" Photoshop plugin by Thomas Fiddaman, available here:
http://www.sd3.info/pf828/PFree/PFree0-1.html
There is also some mild chromatic aberration at 500mm, but at normal print sizes, I can barely discern it. And it's correctable if you really want to get rid of it (see the CAfree plugin at Thomas Fiddaman's website that I linked to above).
Filters
This lens requires 86mm filters. They're somewhat expensive, although you can get some pretty cheap ones on e-bay that actually work fine, for my purposes.
Summary:
If you are on a budget, this is a pretty sharp, lightweight lens that will give you very good pictures if you stop down the lens somewhat, and do some post-processing in Photoshop. But if you are interested in flying birds or aircraft, the lack of an autofocus limiter may be very frustrating.
Other reviews
I have used quite a few lenses and cameras, and you can see all my reviews below:
Canon 100-400 - fast autofocus, good optics make very good wildlife lens. But loses some sharpness at 400mm, and becomes very difficult to use with 1.4x teleconverter.
http://www.epinions.com/content_171720740484
Sigma 18-200 - good optics, versatile range, but my copies misfocus near 200mm (though I can coax it into working with parfocal technique).
http://www.epinions.com/content_185158569604
Sigma 18-125. My first attempt to use a Sigma DC lens. Had front-focus problem at all focal lengths. Did not try a second copy as I switched to 18-200.
http://www.epinions.com/content_152606051972
Sigma 28-300. My first lens for my Canon 300D, purchased before Sigma released any DC lenses. It was pretty good considering its wide range, and focused quite accurately. But 28mm isn't very wide on a DSLR.
http://www.epinions.com/content_153463459460
Digital Cameras
I have also used a handful of small digicams, in my quest to find the perfect travel pocket camera. Here are my reviews:
Ricoh Caplio R3 - my favorite small camera, with its 7x optical zoom, 28mm wide angle, astonishingly small size, very good image color and detail, image stabilization, and voice recorder mode. But the camera doesn't do much in-camera noise-reduction, so you should get NeatImage or Noise Ninja along with this camera.
http://www.epinions.com/content_217558847108
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