Introduction:
As a working professional, the hunt for the perfect capture is a never ending process. As much as I hate reviewing and searching for equipment (I would rather be out shooting), it's a part of life when the quality of your images matter to you. Normally, I shoot with Canon L glass, and have been very satisfied with the results so far, but when I recently acquired a Canon 5D, the search ensued for a good walking lens that was light in weight and fast. I had two options available to me at the time, and one was to go with the tried and true route with the Canon 24-70L or try the Tamron 28-75 f2.8 Di. Having used the 24-70L extensively in the past, I knew what it was capable off, but also knew that it was a heavy lens. So, keeping that in mind I purchased the Tamron in hopes of dispelling my personal belief that all 3rd party lenses were junk. Did taking that risk payoff? Read on...
Lens Description
When I first received the lens from Amazon, I was quite surprised at how small and light the box was. Being used to carrying heavy L glass, my first assumptions weren't positive, as I equated quality with weight. Upon opening the box, I found a nicely packaged black lens complete with hood and end caps. Filter size is 67mm, and there is no aperture ring on the base.
Build quality from an aesthetic standpoint though is rather good, with the plastic bearing a textured finish. There are no creaks or groans while handling the lens, and the zoom ring has enough friction. Turning the focus selector to MF allows the user to manually turn the focus ring. This also has enough friction in it to provide an accurate focus. On the other side of the barrel is a small switch which locks the zoom at 28mm to prevent lens creep.
The included lens cap is of the center-pinch design which I like much better than the Canon offerings. It's a lot easier to remove the cap with the included lens hood attached. Speaking of hoods, the included one is rather flimsy, and probably the worst part of the package. There is no interior surface flocking, and the surface of the plastic is a mix between matte and shiny. Attaching the hood is in typical bayonet fashion and locks in place.
The base of the lens has no aperture ring as I mentioned earlier, so the use of this lens would only be suitable for EOS cameras that can control aperture via the camera's body. The mounting ring is made of metal which is nice considering the cheap price. Generally, the lens is put together quite well, and my assumptions where starting to turn positive. However, the most important aspect is image quality and without further ado, I'll move on towards my observations with this lens and the Canon 5D.
Image Quality and Performance:
One thing that really attracted me to this lens was the fact that it maintained a constant aperture of f2.8 at all focal lengths. However, most lenses don't do a very good job of maintain sharpness wide open or completely stopped down. I'm more interested in f2.8 performance though, as a lot of my work is done in lower light. The fact that the 5D is a full frame sensor camera, also strains a lens design by showing flaws at the edges of the image circle.
All of my tests were performed using a tripod, and having the camera set to ISO 100, RAW, and mirror lockup.
*F2.8: Center of the image was sharp with minor softness at the edges.
*F4: Center of the image was sharp with no corner softness
*F5.6: Center of the image was very sharp with no softness at the edges.
*F8: Center of the image was tack sharp with no softness at the edges.
I only tested to F8 as these where the most commonly used f/stops that I used in my particular style of photography. However, the results were very pleasing, with only minor corner and edge softness at f2.8. The lenses sweet spot begins at F4 which is also a very useable aperture. Color rendition and contrast where also surprisingly good, and while I didn't have a Canon 24-70L next to me to compare with, I did have a few photos taken with that lens that I used to get an "eyeball" impression. Contrast and color where very similar, with no lens being worse than the other.
Autofocus performance of the lens was also pretty good, although nowhere near as fast as Canon's USM offerings. The focus ring does turn when the camera is focusing though, and does take a bit of getting used too. Sometimes my finger rubs up against the focus ring while it's turning, which can be a distraction. Motor noise since it's not USM is also louder than Canon's offerings, but nothing that I would consider a detriment.
Conclusion:
The Tamron AF 28.75 f2.8 DI lens is an excellent value. It's well built, very light, and quite fast. At f2.8, image quality is good enough for most portraiture work, although some corner softness is evident. Stopped down to f4 or smaller, this lens would make an excellent landscape tool, with center and corner sharpness being excellent, even on a full frame sensor. Color rendition and contrast is also superb, and honestly in my eyes rivals that of the venerable Canon 24-70L, at 1/3 the weight and 1/3 the price. Overall, I am very pleased with my decision, and have rethought my original assumptions regarding 3rd party lens manufacturers.
