Which 1.4x TC for the EF 70-300 IS?

I understand that the Canon 1.4x TC does not work with the 70-300 IS. But it appears that both Kenko and Tamron 1.4x TCs may work (with some limitations in AF?). My questions are:

1. Has anyone tested the Tamron, Kenko or both TCs with this lens? How do they compare?
2. Any other TC that is compatible with this lens?

Many thanks.

Kenko Pro and Tamron SP TCs will work but I doubt you'll like the results IQ wise.

gasrocks wrote in post #8071071
Kenko Pro and Tamron SP TCs will work but I doubt you'll like the results IQ wise.

Thanks, I realize IQ won't be great. I just thought that it would allow me to get a feel for the longer FL (while spending less than $200!) and see whether I'd like a 100-400L in the future.

I can see a cheap chance to try longer but whether the 100-400 is the right lens for you is a whole 'nother matter IMO.

I own the Kenko Pro TC and used to own the 70-300IS. While the TC did technically work with the lens, auto focus was slow and would hunt under anything less than ideal lighting. Also, image quality was not very impressive, so I gave up on using the TC with that lens. This was with a Digital Rebel XT body.

The Kenko does work very well with my 70-200 f/4 L IS and 40D combination, though.

Just crop a third of the way into your image to see if 400mm is right for you. You already admitted IQ and AF are going to suck, so why pay $150 to confirm it?

Rent a 100-400 for a weekend. Cheaper than buying a TC that won't give you good results with the lens you have.

Used the 70-300 and Kenko in Africa a few years back...before I realized the 100-400 would be purchased eventually anyway. But if you cannot afford a 1-4 it is a decent option IMO....I tested the 70-300 with tc against the Tokina 80-400 and the IQ of the Canon was BETTER!

Here are a few edited shots, they are not 100-400 sharp but stop down to f9 or 10 and they are fine....AF will work if you tape the pins of the TC. I only sed it when really necessary but did come in handy!!

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DOn't forget to read this thread:
https://photography-on-the.net/forum/showthre​ad.php?t=41922

Neilyb wrote in post #8071620
Used the 70-300 and Kenko in Africa a few years back...before I realized the 100-400 would be purchased eventually anyway. But if you cannot afford a 1-4 it is a decent option IMO....I tested the 70-300 with tc against the Tokina 80-400 and the IQ of the Canon was BETTER!]

Those are awsome shots, thank you!

MPCman wrote in post #8071711
DOn't forget to read this thread:
https://photography-on-the.net/forum/showthre​ad.php?t=41922

Yes, thanks. I saw the entry on the Kenko 1.4X but this was the 70-300 DO, which is a bit different.

I agree with Scott M. I have the 70-300 ISM and the Kenko 300 Pro and have the same issues. The 70-300 is already soft at 300 and the Kenko compounds the problem slightly. Auto-focus is just OK even in very good light at the long end. As a result, I hardly use the two together unless I feel like its absolutely necessary. I'm still on a 30D so I'm a bit wary of over-cropping but I'll try to post some comparison shots (non-TC cropped vs. uncropped TC) if I get a chance. As it stands, I'll probably hold on to the Kenko for when (hopefully) I get one of the 70-200 L's...

swampass2 wrote in post #8072381
I agree with Scott M. I have the 70-300 ISM and the Kenko 300 Pro and have the same issues. The 70-300 is already soft at 300 and the Kenko compounds the problem slightly. Auto-focus is just OK even in very good light at the long end. As a result, I hardly use the two together unless I feel like its absolutely necessary. I'm still on a 30D so I'm a bit wary of over-cropping but I'll try to post some comparison shots (non-TC cropped vs. uncropped TC) if I get a chance. As it stands, I'll probably hold on to the Kenko for when (hopefully) I get one of the 70-200 L's...

My 70-300 IS is as sharp in the centre as my 100-400, edges are not so sharp but respectable considering the price range of the lens.

here's a couple quick shots that were the first i took with the lens, and my kenko 1.4X...i think image quality doesn't suffer as much at all when the subject is still somewhat close...auto-focus is interesting...if you back it off a bit center point works fine...if you're maxed out the lens will hunt...using the other focus points though works better

DreDaze wrote in post #8073944
here's a couple quick shots that were the first i took with the lens, and my kenko 1.4X...i think image quality doesn't suffer as much at all when the subject is still somewhat close...auto-focus is interesting...if you back it off a bit center point works fine...if you're maxed out the lens will hunt...using the other focus points though works better

i know the exposure is off on these...but i've since discovered that the lens needs to be adjusted to about -2/3 a stop when using the TC

Pretty good, thank you!