1.4 x convertor versus a 2 x convertor

wegotitugetit

wegotitugetit

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i currenlty have a 2x convertor and on my 70-200 f4 it wont auto focus it just searches as it makes it F8

now in a previous thread something got mentioned that i could use a 1.4 convertor at 5.6 so is my theory correct in saying if i get a 1.4 convertor i can use the auto focus with it ?

instead of F8 with no auto focus
 
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wegotitugetit said:
i currenlty have a 2x convertor and on my 70-200 f4 it wont auto focus it just searches

now in a previous thread something got mentioned that i could use a 1.4 convertor at 5.6 so is my theory correct in saying if i get a 1.4 convertor i can use the auto focus with it ?
Click to expand...


Correct the 1.4x will give you a 98-280mm f5.6 lens with AF, the 2x gives you a 140-400mm f8 manual focus lens
 
Yes, the AF won't work on a XXD above f5.6, something to do with needing enough light (AF is done before the aperture closes down again)

the 1.4 works fine on my 70-200 f4L IS, sharp as a tack, I can't see any degradation of IQ.
 
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wegotitugetit said:
right so anything above f5.6 will not auto focus ?
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That's what they say, though I believe it isn't entirely correct, I think it won't with a Canon TC.

The f5.6 is the widest though, the lens will autofocus with the aperture wide open then shut down to the aperture setting.

If you have the 70-200 f2.8 then it will, but IQ isn't supposed to be so good with the x2
 
oops. missed the edit. Yes, have used manual on the 100-400 with the 1.4TC attached.
 
wegotitugetit said:
thanks looks like i may be looking at one now lol
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there are several kenko 1.4x teleconverters so make sure you get the right one (i.e.the best one).

Kenko 1.4x Pro 300 DG

^^^^ The designation might be in a different order but that's the one you want anyways.

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adsayer said:
there are several kenko 1.4x teleconverters so make sure you get the right one (i.e.the best one).

Kenko 1.4x Pro 300 DG

^^^^ The designation might be in a different order but that's the one you want anyways.

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Click to expand...

i currently have that in the 2x but will be looking to swap it now or sell it and get a 1.4

thanks for all you replys
 
TC's are really designed for the primes like the 300mm f2.8, however, they are also tending to be used with zooms nowadays. Personally, I think the performance is strictly average on the 70-200mm f4 or 70-200mm f2.8 (although apparently vastly improved on the new f2.8 version, although I'm not spending £2000 to try it out)

The canon TC's will only autofocus upto f5.6 (lens + TC combo) on canon XXXXD, XXXD, XXD and XD models. The only exceptions are the 1D series camera's where they will autofocus upto f8 (f5.6-f8 centre focus point only)

The Kenko and Sigma TC's are really the only other brands worth considering

F-stops are f2.8, f4, f5.6, f8, f11, f16 everything in-between is a 1/3 1/2 f-stop

You lose 1 f-stop of light with a 1.4x TC, slows the autofocus down, and my experience of the canon TC, no loss of IQs

You lose 2 f-stops of light with a 2x TC, slows autofocus even more, and you do lose IQs (detail)

What you need to remember is, performance of the lens and TC will be greatly effected by light conditions, don't expect miracle's in dull light.
 
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