Product Description

A Teleconverter is a great way to extend the focal length of your lens. This Teleconverter will extend the focal length of your lens by 2x giving more magnification. The Tamron Pro series Teleconverter offer superior optical construction for improved image quality.

Product Details

• Color: White
• Brand: Tamron
• Model: AF20PC-700
• Dimensions: .55 pounds

Features

• Increases focal length from same camera position by 2x
• Superior performance for unsurpassed image quality and ease of use
• Fits easily between lens and camera body
• Includes carry case
• For use with Canon SLR cameras

From the Manufacturer
Simply fit a Tamron teleconverter between the lens and the camera body to increase a lens focal length, giving you extended telephoto capabilities so you can take photos with greater magnification from the same camera position. Tamron's AF teleconverters are compatible with most AF (autofocus) and autoexposure cameras.

SP for "Super Performance"
Tamron's SP-series lenses are designed to achieve top optical performance. Ground breaking design concepts give these lenses unsurpassed image quality and ease of use while setting new standards for future generations of lenses.

Customer Reviews

Double your focal length
I realize now that I probably would have been fine with the non-PRO version of the teleconverter -- I'm not certain whether the differences between the PRO and standard actually justify the extra cost (unless you use Canon L lenses perhaps). But that is neither here nor there.

The Tamron SP Autofocus 2x Pro Teleconverter doubles your lens' focal length and adds two f-stops (meaning you'll be getting 1/4 the light with the teleconverter). This is the same for all 2X teleconverters. The addition 2 f-stops will make it difficult to use autofocus unless you have a fast lens and lots of light to work with. You'll also want to use the teleconverter with a long telephoto lens.

The Tamron SP Autofocus 2x Pro Teleconverter works as advertised with 35mm and digital cameras. I've had no problems using a Tamron 70-300mm lens with this teleconverter on a Rebel XT aside from the expected auto-focus issues. There are a few issues I noticed though beyond the typical problems found with any 2X teleconverter:

(1) The teleconverter causes autofocus to misbehave with some lenses. The only lens I've ever had this happen with is a Sigma High Speed 28-70mm f2.8-4 zoom. It wasn't just that the autofocus couldn't achieve a lock but seemed to be more of an incompatibility issue with the lens focusing in and out nonstop.

(2) The Canon Rebel XT kit lens - and probably all EF-S lenses - will not phyically FIT into this teleconverter. The EOS digital-only EF-S mount lenses won't physically fit in standard 35mm cameras either so this isn't a total surprise.

(3) Using this teleconverter with a non-auto-focus manual-only lens (or a telescope) will stop the shutter release button from functioning. I understand this is a fairly common problem with teleconverters. The solution is, when attaching the teleconverter to the camera, to avoid rotating the teleconverter completely so that it does not lock in place. This ensures that the camera and teleconverter electrical contacts are not engaged.

I find the Tamron SP Autofocus 2x Pro Teleconverter quite useful though perhaps a bit overpriced for those of us without premium lenses.

Tamron vs Canon SP Autofocus 2x Pro
I am a professional that uses Canon L lens only and was using Canon Teleconverters both 14x and 2x that I use extensively without a Problem. But, I have decided to go with the Tamron SP Autofocus 2x & 14x Pros.

Why? I have done extensive testing on the four teleconverters and have found that there is no noticeable difference beween like teleconverter. The only exception is the Canon's are heavier and longer and protrude into the lens but are not any better than Tamrons. Another professional friend of mine also looked at the results and was equally surpised.

Tamron's will work on more lens as they do not protrude into the lens like the Canon's do. Remember that lens will only auto focus if you are f8 or less (bigger)lens f-stop. If you add a 2x to an f4 lens it will not autofocus. I manually focus when I have a long telephoto lens on to get out to 800mm but this means with my f4 lens it is really now f8 so requires manual focus. Tamron has a very good little manual that explains all of this. Good luck, Howard

poor performance on full frame
I put this on a 135 f/2L lens on a full-frame Canon, and the result is pretty mediocre. There is a huge amount of vignetting, even stopped down to f/8. Looks like the vignetting might not show up much at f/8 if cropped to match a smaller sensor. Exposure is off by 1.5ev or so, and images have a soft look with a fair amount of chromic aberration.

In the box was a little warning from Tamron that says "This teleconverter is not designed for digital use."