300 f2.8 + 2x II TC or 1.4x Canon + Kenko Pro 1.4x

[CCRII]

I heard a rumor that you could get faster AF from a 300 f2.8 and 1.4x canon along with a Kenko Pro 1.4x tc. I just wonder about the image quality of this combo? I am pretty sure my Canon 2x TC is rubbish (bought second hand) and that I have to purchase a new one. But I am considering the afore mentioned combo. Anyone have experience with it?

[Roy C]

I have not got this lens but have tried stacked 1.4 tc's (Canon and Kenko Pro) with a couple of my lenses and I reckon IQ is just as good if not slightly better than a single 2x tc. When you use stacked tc's the camera will only see one of them so in your case will show f4 and not f5.6 as with a 2x - this could effect AF speed.

[CCRII]

I have not got this lens but have tried stacked 1.4 tc's (Canon and Kenko Pro) with a couple of my lenses and I reckon IQ is just as good if not slightly better than a single 2x tc. When you use stacked tc's the camera will only see one of them so in your case will show f4 and not f5.6 as with a 2x - this could effect AF speed.

Thanks Roy. Yeah as I understand it, it would give the 300 f2.8 588mm focal length with the faster focus of just a single 1.4x teleconverter and also giving you f4 instead of f5.6. I am not sure how well this works, but have had am definitely interested in faster focus and a lower f stop although I have found I can never use the lower f stop anyway with a tc unless the subject is absolutely static. I am just wondering which kenko pro works this way?

[hollis_f]

Thanks Roy. Yeah as I understand it, it would give the 300 f2.8 588mm focal length with the faster focus of just a single 1.4x teleconverter and also giving you f4 instead of f5.6.
Nope, two stacked 1.4s will give you f5.6, exactly the same as a 2x converter. So AF should have the same performance. The camera will only know about one of the TCs so it will think that it's f4 (that's what'll appear in the Exif).

I'd go for two 1.4x rather than a single 2x as it gives increased versatility - you can always just use one of them when speed is more important than reach.

[timp55]

Whats the feeling about comparing a 300 F2.8 + 2 x 1.4 with a 500 F4? Cost wise the 300 is cheaper but loses a stop at approx 600mm against the 500. I'm currently saving for the 500 but am wondering if a 300 + TC is a better way to go, more flexible, slightly cheaper but some loss of absolute quality.

[Roy C]

Whats the feeling about comparing a 300 F2.8 + 2 x 1.4 with a 500 F4? Cost wise the 300 is cheaper but loses a stop at approx 600mm against the 500. I'm currently saving for the 500 but am wondering if a 300 + TC is a better way to go, more flexible, slightly cheaper but some loss of absolute quality.
From what I have seen and read the 500 would be much better than the 300 with a 2x. I suspect that the 500 with a 1.4 would still be better than the 300 + 2x.

[timp55]

Roy, by 'much better' I assume you're talking image quality. How about the fact that I'd be getting close on 600mm but with the ability to drop back to 300 or 420 if reqd. I was only thinking of the TCs in respect of the 300 2.8.

[Roy C]

Roy, by 'much better' I assume you're talking image quality. How about the fact that I'd be getting close on 600mm but with the ability to drop back to 300 or 420 if reqd. I was only thinking of the TCs in respect of the 300 2.8.
Yep, I was talking about IQ 'timp' .

[chrisli]

I think the difference between the 500mm f/4.0 with 1.4TC and the 300mm with 2.0TC is the 300mm you can still handhold the combo, but not with the 500mm, I find the IQ quite acceptable, since I am using both combo. Attached here is a pic taken with the 300mm combo handheld.
http://i176.photobucket.com/albums/w195/chrisli023/_MG_6600.jpg