Canon 1.4 teleconverter...version II or III...please help...

Dear Good Folks

I am writing with a pesky question that may be of interest to many of the folks around here...I am looking for information about the Canon 1.4x teleconverter...this would be used with the 70-200 f4 and the 300 f4 only, in my case. Is there a noticeable difference between version II and version III of the same teleconverter? Either in AF speed or IQ?
At the moment I'm using the Kenko Pro 300 teleconverter, and I assume (perhaps incorrectly) that the Canon model will be a step up?
Any information you might have would be so helpful...please bear in mind that I've already read countless reviews online, and am looking instead for HANDS-ON EXPERIENTIAL information...

Thank you so much for your help!

it makes no difference on the lenses you mention. Canon TCs are much better than 3rd party.

Thank you, Arash, I appreciate your taking the time...you've saved me $100...expect a cheque in the mail...

Jack,
I've used both the Kenko and the Canon 1.4xTCII. I did some head to head testing with the two and found virtually no difference. The Kenko may have even been a tad bit sharper. The Kenko did cause my images to "jump" during capture when used with my 40D and 1-400L while the Canon did not. It didn't happen when used with a prime lens.

Thanks a lot Steve, it's much appreciated. I opted for the Kenko b/c all reviews indicated that the IQ was identical...any thoughts on difference in AF speed? I assume they're roughly the same. I love the 1.4 on my 200mm f2.8...

Jack,

You should keep in mind that the 1.4x III is supposed to have improved performance when used with the new Canon telephoto lenses. If you plan to buy one of these or sell your 1.4x some day, you may wish to get the 1.4x III instead of the 1.4x II. I own both of them and as Arash said, there is no real difference with the current lenses. Another thing to note is that unlike the 1.4x, the 2x III has a noticible improvement over the 2x II.

Thanks Jim. Most helpful.

Agree with Steve....Neither myself nor any reviews that I found saw much if any difference in the 1.4x II Canon vs Kenko. I don't know what the Canon 1.4x III TC brings to the table. No comment on AF either, as much as I would like to, I have no objective way to test that and say what's better. All I can say is that they "feel" the same to me.

I own a soligor 1.4x and the sharpness is as good as Canon. The AF is faster then Canon but not as accurate because the Canon converter slows down to get better AF. That's my opinion with my canon 40d and 300/2.8L is.

Hi guys,

I have recently got a 2nd hand 500mm f4 MKI and already have the 1.4x and 2x MKII canon teleconverters. Is is worth an upgrade to the MKIII for better IQ or AF for this lens or are the improvements mostly for the newer versions of the lens?

Regards

Craig