Instruction: Given a question and the related document, and generate the answer to the question based on the information provided in the document.

Input:
Question: Will this work with a Canon T3i, using a Tamron 70-300mm Di VC SP USD lens?
Document: The front [glass] element of the converter protrudes into a space that is too close to the rear element of most lenses when mounted, including zooms and primes, especially EF-S lenses, to the point where they can come into contact. If you've ever used a 70-200mm f/2.8 or f/4 lens, you'll notice that the rear element is recessed somewhat, by at least a quarter inch on my SP Tamron 70-200mm f/2.8.
I'm using the Canon version and I've had nothing but a positive experience with it. I've used it on the following lenses AND retain the ability to use auto-focus, unlike the Canon 1.4x model, which costs twice as muchCanon 300mm f/4LCanon 400mm f/5.6LCanon 40mm f/2.8 (Pancake)Canon 50mm f/1.4This is an excellent TC as long as you understand it's limits with the type of lenses it will work with.
The already excellent macro capability of the Tamron 70-200 is improved using this converter as well. I am pleased to own it.Why haven't you bought it yet?
I got the Tamron 70-200 for portraits. I added the Tamron 1.4x teleconverter for birding and other nature stuff. And I use both on my canon 60D and 5D. There isn't much I can say that others haven't about it, it just works. It doesn't change the dynamic of the lens at all, only reducing it to an f/4 lens, at which it's still sharp. Stopped down to f/5.6, it is amazing. The price is right too.
I have had the white versions of this Tamron SP Pro 1.4 and 2X Teleconverters for years. They are a perfect addition to your wildlife setup. This is a review of the 1.4X so I shall concentrate on it.I have no problem spending the money necessary for the best so why the Tamron over the Canon? Because the Canon teleconverters have a protruding element into their lenses, this does not.
It can work with other lens types, as I wrote earlier, it's a roll of the dice. Fortunately, this converter is not priced for pros, and neither is Tamron's 70-200 2.8, but the combination is what this teleconverter was made for.And that combination is what I would now like to talk about.
With a combo of my Nikon D300s+Nikon 80-200mm 2.8 and this Tamron SP AF 1.4x, I was able to get great up-close soccer photos! I can only speak for my lens combo, make sure you get the "SP" version of this TC. At 2.8, it will drop you a step to f/4.0, which is great during the morning/daytime games.
This is excellent. Right price and decent quality. I can use it with both the T2i and 6D with no problems. Using 18-250 Sigma on T2i and 70-300 Canon on 6D. AF is pretty good if there is enough light, otherwise manually focus.
Both were same price. The converter is pristine and the front and read caps protect it sufficiently. Wonder how the 2x converter would fare? If you use the converter on a fast lens, you will be happy with the purchase. My Tamron 200-400mm zoomed all the way out is a f5.6 lens, and the converter will only work at f8.0 min. Should be sufficient for daylight.
I have only used the 1.4x converter for night photography. I bought it specifically to photograph the moon. Used it with a Tamron 200-400mm and on a Canon 100mm. I was amazed at what the converter did for the 100mm. Got nice twilight shots of the waxing crescent moon the day after Christmas. Included in the shot were Venus and about 20 other stars. This was a bonus, and I am using this shot as my current screen saver.
Answer: yes, i'm using a canon 60D and this teleconverter with this 70_300 lens. Perfectly fine.