The SP AF PRO-series teleconverters, with a re-designed optical construction (4-group/5-element for 1.4X and 4-group/7-element for 2X), are designed to be used with lenses that are F/2.8 and of focal lengths of 90mm or greater. This would make the use of the SP teleconverters ideal for the Tamron SP90mm F/2.8 macro, 70-210mm F/2.8 and 300mm F/2.8. Relative illumination is significantly improved resulting in better overall contrast and resolution across the entire image field. In addition, chromatic aberration and astigmatism are better compensated for by virtue of the use of higher-grade glass materials and more sophisticated design techniques than used in universal-type teleconverters. When used with lenses with smaller maximum apertures (F/4 and F/5.6, for example), there will be little difference in image quality as compared with the standard Tamron teleconverters. When used with lenses wider than 90mm, the SP teleconverters can actually comprise image quality.
Most Liked Positive Review
Works with Nikon 70-200 f/2.8 VR
Works with the Nikon 70-200 f/2.8 VR lens - the big $1600 one - even though Nikon will tell you only their TC will work with it. Make sure you get the grey Pro version (which I believe is made by Kenko but carries the Tamron label).
Reviewed by 18 customers
Makes a fast 50 mm into a great portrait lens. I use it mostly for wildlife and landscape, but have also used it to make a long tele into a VERY long tele for sports. Used carefully, it makes a remarkably sharp pairing with a quality lens. The photos have excellent central sharpness, and only a little falloff at the edges, but this is rather nice for closeups. It centers the eye on the subject. For use on Canon cameras, be sure to mount it to the lens first, then attach both to the camera. If attached to the camera first, the exposure results can be variable.
This is a very nice teleconverter, which is light, handy, and easy to use. It provides excellent results when used within its capabilities. Like all 1.4X teleconverters, it diminishes light transmission by 1 stop, but with today's digital cameras, that is no real problem. If the effective f-stop drops below 5.6, you may lose autofocus, but not autoexposure. Note! With Canon lenses, it is almost always necessary to add items to the lens stack before connecting the stack to the camera. If you attach the converter, then the lens to the camera, they may not work properly together. Though not quite the quality of the very expensive Canon dedicated converters, this does a great job for most purposes, and I think it will be a good value for use with the 100-400 Canon L Zoom.
After reading many reviews about the 2x and the 1.4x Tamaron Teleconverter, I tried both. As the review comments stated, the auto focusing on the 2x was quite slow and not acceptable for me. The auto focusing for the 1.4x was much faster and acceptable for me. I will only use the 1.4x Teleconverter for very specific long range photos, so the slower auto focusing will not be a problem.
The autofocus works perfectly with my Canon 600 , and 70-200 2.8 lenses. I also use it with a Sigma 500. I had 2 sets (and 2x) for Sigma and Canon, NONE of them worked for autofocus. These slow the focus down very slightly but tolerable. They work GREAT.
I was quite pleased by the quality of this teleconverter. The auto-focus did slow down a little bit but nothing to worry about. Good product for a good price!
I use it with the Tamron 70-300 VC, a VERY good lens. The teleconverter is equal to Canon's on my Canon 5D Mark II. I did find that the AF was a bit slow but not a real concern.
I used this Tamron 1.4 X extender with my Tamron 18 - 270 zoom on a Canon 60D, and the results were just what I would have expected - moderate but acceptable effect on sharpness. A good addition for occasional "long shots.." Yes an excellent 120 - 400 zoom would yield superior results at a cost of $1,000, but for less than $150, a great alternative for that once in a while need. Also, light and easy to carry. If you must have auto focus and image stabilization then go for the big bucks option - I come from the time when neither was available, but photos were still sharp.
Most teleconverters are not very good at retention of image quality. This one is. Compared to others I have used, it is remarkable.
To ensure proper function, as is true for most Canon lens focal length extenders, it is always best to attach the extender to the lens, then the pair to the camera. Attaching the extender to the camera, then adding the lens may result in improper function or focusing.
Easily attaches to my Canon 400 mm lens but cannot autofocus with my 50D. Still, provides clear pictures and is a great value compared to purchasing a 500 mm lens.