Canon 70-200 f/4 L IS with 1.4x or Canon 70-300 f/4-5.6 L IS or 300 f/4 L IS over Tamron 70-300 VC?

dheerc wrote:

So, if I understood it correct, according to you the 70-300mm L is better than the 70-200mm L with 1.4x ?
I am very curious now. Did you use a Full frame or an APS-C sensor camera in your test? The reason I ask that is because I do not plan to go full frame anytime soon and I own a Canon EOS Rebel T3. I would most possible upgrade to a 70D at the best so, on a cropped sensor, at least with my T3, the 70-200L seems to do better with the 1.4x.
As far as TDP reviews are concerned, I have seen them all and yes, that is what prompted me this question int he first place. I saw a lot of people researching on the 70-200 with 1.4x vs the 70-300 L and I thought it would be equally good if not better.
As I said, I am more worried about the longer end since that is where most of my shots come in. So in that aspect, would you even consider the 300 L as a fair comparison or just between the 70-300L and the 70-200L?

Yeah my 70-300L definitely did better from around 175mm-300mm (very slightly near the 175mm end and quite noticeable so at the 280/300mm end).

It doesn't seem surprising to me that the bare lens would do better than the other plus a TC.

Also note that the AF is 50% faster using bare lenses than with 1.4x TC III.

I used a 5D3 for that test, but as I said, the optical differences between them appeared to be largest center frame area wide open so the same should apply to aps-c. At the FF edges the performances was actually more similar than in the center. At f/8 the performance became more similar.

I've never used the 300 f/4 IS but I did use the 300 f/4 non-IS once upon a time. I never got to directly compare the 300 f/4 non-IS since that had been sold by the time I got the 70-200 and way before I later got the 70-300L.

I'd imagine that the 300 f/4 primes are a bit better at 300mm and I'm pretty sure they take the 1.4x TC better (getting you to 420mm) and provide AF for sure and f/4 does give you a full stop speed benefit and option for less DOF for sports. The 70-300L can take a Kenko DGX 1.4x TC to get to 420mm and it is better than upscaling (at least on 5D3 density not sure about 70D) and it allows AF on 5D3 (not sure about 70D).