NOTE: PLEASE SEE THE COMMENTS SECTION FOR THE LINK TO REVEAL THE AMAZON-HOSTED CUSTOMER IMAGES DISCUSSED IN THIS REVIEW.

This is the third model in Tamron's line of 90mm f/2.8 macro lenses and the first to offer image stabilization (called vibration correction or VC by Tamron). It's available for Canon, Nikon and Sony mounts--I purchased the Canon mount version. Tamron lenses have always been considered a low-cost alternative to the brand name lenses albeit with a reputation for lower build quality, quality control, and optical quality. This has started to change however, as they have been producing some real winners lately, in particular the 24-70mm Di VC that was released in the spring of 2012.

Happily, this new version of their 90mm Macro continues that trend. It's predecessor, the AF 90mm f/2.8 Di SP 1:1 Macro, was already a well-regarded contender in a somewhat crowded field of ~100mm macro lenses also occupied by Canon, Sigma, Tokina, and Zeiss. It remains the lightest most compact lens of the group at 400g and is optically excellent, however the lack of image stabilization leaves something to be desired.

The Canon EF 100mm f/2.8L IS is the standard bearer, but is also quite heavy at 625g. The new Tamron has gained an inch in length and is now nearly as long as the Canon, and the weight has increased to 550g, so it is no longer as compact. Still, the difference of 75g or 2.6 oz can matter if you're carrying it around all day, and it's still 50g lighter than the Canon non-IS 100mm Macro.

Here are some of my initial impressions: Auto focus has been greatly improved; the new ultrasonic silent drive motor lives up to its name and is quiet, snappy and accurate. Sharpness and contrast are superb wide open across the field. Ghosting, flare, distortion and chromatic aberration are almost non-existent. Light fall-off (vignetting) is typical at f/2.8, virtually gone at f/4 and completely gone by f/5.6. Bokeh is smooth and rounded at all apertures. Full-time manual focus override is seamless, simply turn the focus ring and shoot; no more fussing with that push-pull clutch mechanism. In short, Tamron has hit it out of the park with this lens and I really like it!

I compared this lens in several tests against the Canon EF 100mm f/2.8L IS and the Canon TS-E 90mm f/2.8 Tilt Shift Lens, two Canon lenses with a similar field of view that consistently rate at the top of the Canon line in terms of image quality. Here are the results:

Sharpness and contrast: It's a virtual tie with all three lenses. If I have to set them apart I would say that wide open the Canon 100L is a hair sharper than the other two, because the blacks are the deepest. But the Tamron really impresses with how sharp it is into the corners, and you have to zoom in to 1:1 magnification or higher to really see any difference. Canon 100L wins, but only by a hair. Stop them down a bit and there is no difference at all.

Light fall-off (peripheral illumination, or vignetting): The Canon 90mm TS-E wins by a landslide with no light fall-off even at f/2.8; as would be expected for a tilt-shift lens. The Canon and Tamron macros have similar amounts of vignetting wide open which is almost gone by f/4. The Canon 100L has an edge over the Tamron if you own a newer camera like the 5D Mark III with built-in lens aberration correction and you only shoot JPEG. Otherwise, if you shoot RAW, you can just correct this in post.

Brightness: Sometimes called the T-stop value in the motion picture industry, it's how much light the lens actually gathers at a particular f-stop. In my tests, the Tamron is 1/3 stop brighter than my Canon 100L which is 1/3 stop brighter than the 90 TS-E (tested at f/5.6).

Weight: Canon 100L. 625g; Canon 90 TS-E, 610g; Tamron 90 VC, 550g. Tamron is the winner.

Cost: The Tamron is the clear winner; the price is $200 more than the non-VC version but it's still a bargain compared to the Canon 100L. Check current pricing as the cost has dropped nicely since it was released.

Field of View: Just for reference, the Tamron 90mm actually falls right between the Canon 90mm TS-E and the Canon 100L.

The following apply to the Canon and Tamron Macro lenses only (The Canon TS-E is a manual focus lens with no IS):

Autofocus: Both the Canon and Tamron macros have a focus selector switch with Full, Normal limit, and Macro limit ranges. In focusing back and forth between a close and far subject, they performed equally well, even in low light. This is very impressive for the Tamron since auto-focus is one area where third party lenses tend to lag. They both hunt a bit in the true macro range, or if there is nothing contrasty to lock in on. After some practice, I was able to get the Tamron to auto-focus in the macro range, but many dedicated macro shooters shoot in manual and simply move the camera to focus. A tie.

Image Stabilization: With the Tamron I was able to get sharp results hand-holding down to 1/6 of a second before the keeper rate started to drop off, while with the Canon 100L, the keeper rate started to drop off at 1/10 second. Plus, the Canon IS motor constantly makes a high-pitched whine; it's not very loud but is a bit annoying compared to the Tamron which is virtually silent! I was pleasantly surprised that the Tamron won here.

In summary, the Tamron actually comes in with a slight edge in many respects and is the better value. I wouldn't hesitate to recommend this Tamron macro lens above any 100mm 1:1 macro lens, including the Canon 100L, which has until now held the top spot in this field. Check out some of the images I posted. Happy shooting!

UPDATE 3/21/2013: After having used this lens for nearly three months now, my opinion of it has only gotten better. It balances on my camera better than the front-heavy Canon 100L, and the virtually silent image stabilization (aka Vibration Correction) is a real dream. This has become my favorite macro lens. I also still really like the Sigma 150mm f/2.8 Macro OS for its great image quality, but the size and weight of the Tamron is so much easier to manage.

UPDATE 5/7/2013: I posted some photos shot at very small apertures (f/25 - f/32) with a macro flash. This lens holds up very well when stopped down. The image quality is very good all the way down to f/22 and surprisingly usable at smaller apertures; even the f/32 shot is OK, on the full res version you can make out the eye of an ant! The AF works at macro distances and there is clearly image stabilization steadying the viewfinder in the macro range, which helps take the shot. I don't understand why this lens hasn't caught on yet. (AS OF 2114, AMAZON HAS HIDDEN THE CUSTOMER IMAGES, SEE COMMENTS SECTION ON THE LINK TO BRING THEM BACK.)

UPDATE 1/25/2014: This has become my go-to lens for product photography. The focal length and macro ability gives the ideal framing and depth perspective for products ranging from jewelry to large TV studio video cameras. You never have to worry about running up against the close focusing distance of standard lenses. Though I have the Canon macro 100 L, I keep this Tamron on my camera 90% of the time. Note: I'm disappointed that Amazon has decided to hide the customer uploaded images from the site. It makes for a MUCH less useful buying experience not to have customer images for lenses and cameras. I encourage everyone to complain to Amazon to get the customer images back. SEE COMMENTS SECTION FOR THE LINK TO UN-HIDE THE CUSTOMER IMAGES.

This is a great lens and it is nicely built, too. I bought it partly because of some enthusiastic comments I had read by other reviewers. Generally seen, I agree that this lens is producing very sharp and crisp pictures. I like it a lot for that reason.
However, the AF does a lot of hunting in less-than-optimal light conditions, which is a general issue with AF in Tamron lenses. I had hoped, based on some of the reviews, that the problem was taken care of, but that does not seem to be the case. For instance, I compared it to the (cheaper) Canon EF 100 mm 1:2.0 USM AF and the Tamron lens does a lot more hunting in AF mode that the Canon, particularly when the light is not so bright. To be fair, this is partly due to the slightly different aperture, but the AF difference is big enough that it is bothersome. In dim light conditions, the Canon will still focus in, while the Tamron will not find a focus at all and you have to switch to manual. That's fine, just as it is fine to do macro pics in manual mode, but the point is, sometimes you want to be able to rely on a fast and precise AF because you're missing the shot otherwise.
So, all in all, a very nice lens with great utility, but because of the AF issues, not a 5 star lens.
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Update Dec. 20 2015: I corrected the 4 stars to 5. The more I use this lens, the more I am impressed with the sharpness of this lens. It is delivering at the level of the 200mm Canon L II lens -- amazingly clear and sharp images. The autofocus issue is really only noticeable in relatively low light. I can live with this, given the other qualities of this lens, including the fact that it shows very little vignetting and almost no ghosting and flaring. Compared to other lenses up and down between 50mm and 135, it has indeed extremely little flaring even at 2.8. The lenses I compared it to were a manual Pentacon 135mm 1:2.8 (M42 mount with EF adapter), a Canon 100mm EF 100 mm 1:2.0 USM AF, and a manual Rokinon 85mm 1:1.4. All had pretty serious flaring at 2.8, except the Pentacon (which is a cheap, fine East German lens from the late 60s) . The subject was our Christmas tree with some (challenging) LED lights, photographed with a tripod at 2.8, ISO 800 and Tv of 1/5.The first image (on the left) was taken with the Canon 100mm, the second (right) with the Tamron 90mm lens. Compare the left half of the two images. Amazing difference.

Notes:

* I'm no expert on the hardware side but this seems a very solidly constructed lens.

* Focus is soooo quiet. It's spooky. It's a bit slow on my Canon 60D but I think that's the camera's fault more than the lens.

* VC is solid; even when I'm up at 3am taking pictures and not so steady it keeps my photos sharp as a tack

* Before it was stolen, I had a 60mm Canon macro lens and I'm almost glad it was stolen as it allowed me to upgrade to this one. It's a great improvement in my opinion.

* Ignore the reviews about gray market lenses if you're planning to buy directly from Amazon as I did. If you buy used.... well, you were warned.

* See my example photos from the lens

* Filter size is 58mm. I wasn't entirely clear on that based on the product listing.

*** If you have any questions let me know; this has become my go-to macro

I am new to macro photography. I did some reading, and I decided that I wanted a 1:1 dedicated macro lens. I narrowed the field to this Tamron lens and the Canon 100mm lens. The scale was tilted in favor of Tamron due to the price difference and the current rebate of $100. This lens has vibration compensation (image stabilization) which is a must for macro photography without using a tripod. Depth of field is paper thin at close range. Therefore I find that I use manual focus together with slight movement of the camera in order to focus on the specific point that I want. The lens is very balanced on the camera. The results are great! I am glad that I bought it, and I highly recommend it.