Converters on a canon crop body?

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I have a 450D and am thinking of getting a converter in the future. Would the 2x or 1.4x converter allow AF on my body? Would the two converters work together or would this really ruin image quality? Is there any difference between the Canon or Sigma converters?
 
footman said:
The important thing is what lens will you be using.

I really think you need to read up on this:

http://www.bobatkins.com/photography/tutorials/tc3.html
Click to expand...

Thank you very much for that article :), it was very useful.

So the converters only cost you 1 stop (1.4x) or 2 (2x) stops respectively? I thought it was a multiplier of the stop you lost too :nuts:.

I heard someone say that the AF would work with the 1.4x converter on a crop body but that the 2x wouldn't? Is this true? According to that article though the 700-200 F/2.8 L would work?

Are the Canon converters much better with the specific lenses it mentions compared to 3rd party lenses? What lenses would still have AF with a third party lens?
 
A f/2.8 lens will AF on any Canon body with either the 1.4x or 2x extender. But not stacked. Crop or not, doesn't make a difference. The limit is f/5.6 always so that means f/4 lenses will AF with the 1.4x extender only.

The pro bodies allow AF up to f/8 so you could in theory stack the extenders on a f/2.8 lens.. but the IQ is wanting to say the least.
 
vaizki said:
A f/2.8 lens will AF on any Canon body with either the 1.4x or 2x extender. But not stacked. Crop or not, doesn't make a difference. The limit is f/5.6 always so that means f/4 lenses will AF with the 1.4x extender only.

The pro bodies allow AF up to f/8 so you could in theory stack the extenders on a f/2.8 lens.. but the IQ is wanting to say the least.
Click to expand...

Thanks :).
 
vaizki said:
A f/2.8 lens will AF on any Canon body with either the 1.4x or 2x extender. But not stacked. Crop or not, doesn't make a difference. The limit is f/5.6 always so that means f/4 lenses will AF with the 1.4x extender only.

The pro bodies allow AF up to f/8 so you could in theory stack the extenders on a f/2.8 lens.. but the IQ is wanting to say the least.
Click to expand...

I think an f/2.8 lens will try and AF on any body as the camera only picks up the 2x TC. But as you say the image quality wont be great unless your using high end primes e.g 300mm 2.8 IS L. see here
 
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I sometimes use stacked 1.4x + 2x tc's with my 300/2.8 on a 7D body. When you stack Canon converters the Camera only sees the converter nearest the lens (the 2x in this case) so will report f5.6 (when it is effectively f8). Auto focus is therefore possible and actually quite good in good light and contrast.
Yesterday I shot exclusively with stacked converters and got some reasonable results.
As has already been said you will need a fast prime for best results.

tufty2.jpg
 
vaizki said:
A f/2.8 lens will AF on any Canon body with either the 1.4x or 2x extender. But not stacked. Crop or not, doesn't make a difference. The limit is f/5.6 always so that means f/4 lenses will AF with the 1.4x extender only.
Click to expand...
Not actually true because when you stack Canon converters the Camera only sees the 2x so will attempt to AF with a f2.8 lens - I took over 300 shots with stacked 1.4x and 2x yesterday on a 7D body and they were all Auto focussed. See my post above.
 
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