I won't go into the properties because to be honest, many here don't care and they don't understand. That's what DPReview and DXOMark are for. I shoot 6A high school sports like football, basketball, baseball and lacrosse and bought this lens shortly after it was released on the recommendation of my local Tamron Midwest rep (whom I met at one of the games I was shooting). I used to rent a Canon 70-200 f/2.8 Mk I and then II. While they produced amazing results (the Mark II version in particular), they were absolute TANKS. After a three-hour soccer game, when I wasn't using my Manfrotto monopod, my neck and shoulder felt like a concrete block dangling from me. NOT SO with this Tamron. In fact, after the first two games, I stopped taking Manfrotto at all. Not having a monopod allows me to be very mobile with the EOS 7D (and now the 7D Mark II) with the Grip. I do feel a little tired towards the end of the shoot, but that wasn't what Canon's beasts were asking for. Tamron got it when they designed this lens - both optically and in terms of physical mechanics. I find the results to be better than the outdated Canon Mark I and on par with the Mark II version, apart from a bit more chromatic aberration at times (okay, I had to add a technical term - sometimes very slight magenta fringing in areas). photo if you know what you're looking for) and it's very well made (Canon's all-metal body is an overstatement - unless maybe you're shooting in combat). The ultrasonic motor focuses very quickly and the VC image stabilization is EXCELLENT. Some have given this lens a lower rating, complaining that it's "too heavy". WHICH TYPE?! It's the smallest and lightest lens in its class, and overall it's optically on par with Canon's latest lens and certainly better than the current SIGMA 70-200 f/2.8 offering (although a new SIGMA 'Global Vision' lens is on the horizon , and these are fantastic lenses). , I have two). It is VERY SOLIDLY built, as good as it SHOULD be. Can it withstand extreme conditions like Canon? Probably not, but I don't make a living from photography and would most likely go the canon route if I had. The lens has a moisture-resistant design which I'd say works very well - I've been caught on more than one occasion at a soccer game with a backpack at the opposite end of the field in the rain (my EOS 7D is weatherproof too). This design also prevents dust from getting in between the lens elements. I use this lens almost exclusively outdoors in the windy and dusty Midwest (except basketball) and have taken over 10,000 photos with it. I have other lenses from both Tamron and Sigma and this lens performs better on my camera more than 90% of the time. Before that, my favorite was my Tamron 60th Anniversary 70-300mm f/4-5.6 (still the best value for money). ANY lens - although this one offers a bang for the buck) and although it's significantly lighter (with longer range) I prefer this one. It's just a PLEASURE to use with AMAZING results. Don't be intimidated by the weight of this lens, especially if you're using a Rebel T-series and the body is significantly lighter than mine. Get your Rebel and you'll look like a SERIOUS photographer with this lens. By the way, many people make the mistake of getting a very capable body and then throwing cheap lenses at it. Cheap glass will give you relevant results. While this lens is a definite investment, Tamron most often offers a $100 discount, making it the best value on the market today at $1400 (SIGMA will respond with a new offer shortly) . I sent the lenses to Tamron for warranty repair and they are very quick with the job. After 6 years the best product in its class. Yes, this lens works with ALL CANON EOS DIGITAL SLR CAMERAS EVER MADE - both full frame and APS-C (if you're interested). Seriously folks, I can't say enough good things about this lens. I've been taking photography seriously for over 30 years and this is the best photography gear I've ever used. I'm also a serious amateur astronomer with quality optics and some very expensive eyepieces and this lens is on par. Third-party lens manufacturers, namely Tamron and SIGMA, used to be the economical choice for those who couldn't afford it and couldn't afford the extra burden of owning Canon or Nikon glass. No longer. They compete against each other and in some cases outperform the big players at a more affordable (and reasonable) price. You can't go wrong.