Canon or Tamron SP, Teleconverter

[Ben]

I just got a Canon 40D and a Canon 100-400 f5.6 IS L lens and I would like to get a 2x converter for it, I can get a Tamron sp for about $100 less than the Canon 2x type II do you have any idea if the Tamron will work as good as the canon I am not sure if the Tamron will work OK with the IS but I know the Canon says it will, also I hope to get a Tamron 70-200mm f 2.8 lens and my understanding is that the Canon converter will not work with Tamron lens so that is another reason I am looking at the Tamron SP. Anyone know if the Canon type II is that much better that the older ones because I know they can be found a lot cheaper.
Any input would be helpful.

Thanks Ben
p.s. I have heard that the 1.4x works a lot better than the 2x anyone know anything about that

[dculp]

Ben,
I shoot with a Canon Xsi and also have the Canon 100 - 400 IS that I purchased with advice from the forum. I originally purchased the 1.4x and tried it out a bit. I ended up sending it back and ordering the 2x. My main reason had to do with the fact that neither will work in the autofocus mode and I was struggling to get tack sharp images in manual focus. I found that the additional magnification of the 2x allowed me to focus better and as they are the exact same price, I could see no down side.

This photo was taken with the 2x in place and in cloudy conditions, but it gives you the general idea.
http://s267.photobucket.com/albums/ii31 ... P_0001.jpg

Sorry, all I can offer is the link as I do not have the photos on this computer. I can't help much with the Tamron question, but I can say that the Canon does a really nice job and if you go Canon, go 2x in my opinion.

David
http://s267.photobucket.com/albums/ii314/dculp/

[bob_r]

You might want to consider a Kenko teleconverter rather than a Tamron. They seem to get a lot of good reviews and I believe certain models will continue to AF even with the 100-400 (the Pro model I believe). I haven't tried either of the ones you listed or the Kenko, but do have Sigma's 1.4X and 2X. I rarely use the 2X since I think it degrades the images too much. I use the 1.4X quite a bit with my macro lens and sometimes with the 100-400 and find the images to be very acceptable. I also stack them on rare occasions, but don't recommend it.

Here's a 100% crop taken with a 30D, a 100-400 and a Sigma 1.4x with no processing other than croppping and reducing the file size for the web.



Bob R