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What is minimum lens aperture for autofocus with 5D / 5D Mk II?

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Tommy Williams

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I know that the center focus point on the 1-series cameras can work at minimum apertures as small f8 (as happens when using the 2x teleconverter on an f4 lens) but will the 5D or 5D MkII autofocus at f8 or does it only work at f5.6 or wider?

I'm asking because I have a 70-200 f4 (not IS--I got it long before that one was available) that I use occasionally with my 20D. I'm upgrading to a 5D MkII and I know that there will be a few times that I will miss that extra reach at the long end. Those times are rare and that's why I'm willing to sacrifice a bit of quality with the 2x extender rather than trying to buy a longer lens.

But then I remembered that you lose two stops of aperture with the 2x extender.

--
Tommy
 
Tommy Williams said:
I know that the center focus point on the 1-series cameras can work
at minimum apertures as small f8 (as happens when using the 2x
teleconverter on an f4 lens) but will the 5D or 5D MkII autofocus at
f8 or does it only work at f5.6 or wider?

I'm asking because I have a 70-200 f4 (not IS--I got it long before
that one was available) that I use occasionally with my 20D. I'm
upgrading to a 5D MkII and I know that there will be a few times that
I will miss that extra reach at the long end. Those times are rare
and that's why I'm willing to sacrifice a bit of quality with the 2x
extender rather than trying to buy a longer lens.

But then I remembered that you lose two stops of aperture with the 2x
extender.

--
Tommy
Click to expand...
i don't know but my new 5d mk2 doesn't autofocus with my tamron SP 1.4x TC and it autofocuses fine on my 1d mk2 and 100-400L lens. so if i have a faster lens, the 5d mk2 will autofocus with a TC?
--
Darrin Lingle
 
Its f/5.6
Tommy Williams said:
I know that the center focus point on the 1-series cameras can work
at minimum apertures as small f8 (as happens when using the 2x
teleconverter on an f4 lens) but will the 5D or 5D MkII autofocus at
f8 or does it only work at f5.6 or wider?

I'm asking because I have a 70-200 f4 (not IS--I got it long before
that one was available) that I use occasionally with my 20D. I'm
upgrading to a 5D MkII and I know that there will be a few times that
I will miss that extra reach at the long end. Those times are rare
and that's why I'm willing to sacrifice a bit of quality with the 2x
extender rather than trying to buy a longer lens.

But then I remembered that you lose two stops of aperture with the 2x
extender.

--
Tommy
Click to expand...
 
As said above, if you use the 5DMkII the minimum aperture is f/5.6 however if you stack a 1.4TC and a 2TC the reported aperture will only jump by the 2TC's 2 stops. Obviously image quality will suffer, but I've tried it with a 300mm f/2.8L IS stacked with both the 2TC and the 1.4TC and autofocus works and the reported aperture is only f/5.6 when it should be f/8. In very bright sunlight I was actually able to get a couple of useable shots with this combination.
 
LeviBuzolic said:
As said above, if you use the 5DMkII the minimum aperture is f/5.6
however if you stack a 1.4TC and a 2TC the reported aperture will
only jump by the 2TC's 2 stops. Obviously image quality will suffer,
but I've tried it with a 300mm f/2.8L IS stacked with both the 2TC
and the 1.4TC and autofocus works and the reported aperture is only
f/5.6 when it should be f/8. In very bright sunlight I was actually
able to get a couple of useable shots with this combination.
Click to expand...
Did you see if the "order" of stacking mattered by any chance?

For instance:

camera> 1.4x> 2x> 300

vs

camera> 2x> 1.4x> 300

I could go out and test it, but figured I'd ask if you had already tried it.

Also wonder if you noticed that one configuration yielded better results than another.
--

Website: http://mikebrum.com/
Photoblog: http://submagination.com/
Filckr: http://www.flickr.com/photos/mikebrum/
 
submagination said:
Did you see if the "order" of stacking mattered by any chance?

For instance:

camera> 1.4x> 2x> 300

vs

camera> 2x> 1.4x> 300

I could go out and test it, but figured I'd ask if you had already
tried it.
Click to expand...
--

They only stack one way. I also noticed that stacking the TC's allows autofocus with a F: 2.8 lens. The images are not very sharp, and I really don't ever plan to use them that way.
 
If auto focus at narrower apertures, or AF in general, is a concern to you - why not skip the 5D line and go directly to the 1D series? Even a used 1D body that is a generation or two back will out do the 5D2 in focusing ability, and with their level of build quality will probably outlast it too.
Tommy Williams said:
I know that the center focus point on the 1-series cameras can work
at minimum apertures as small f8 (as happens when using the 2x
teleconverter on an f4 lens) but will the 5D or 5D MkII autofocus at
f8 or does it only work at f5.6 or wider?

I'm asking because I have a 70-200 f4 (not IS--I got it long before
that one was available) that I use occasionally with my 20D. I'm
upgrading to a 5D MkII and I know that there will be a few times that
I will miss that extra reach at the long end. Those times are rare
and that's why I'm willing to sacrifice a bit of quality with the 2x
extender rather than trying to buy a longer lens.

But then I remembered that you lose two stops of aperture with the 2x
extender.

--
Tommy
Click to expand...
 
Tommy Williams said:
I'm asking because I have a 70-200 f4 (not IS--I got it long before
that one was available) that I use occasionally with my 20D. I'm
upgrading to a 5D MkII and I know that there will be a few times that
I will miss that extra reach at the long end.
Click to expand...
The 20D and 5D2 have the same size pixels so if you crop your 5D2 images to 8 megapixels, you are going to end up with exactly the same image as with your old 20D, although perhaps with less noise. The 20D doesn't have any "reach" advantage over the 5D2 whatsoever.

Kind regards,
  • Henrik
--
And if a million more agree there ain't no great society
My obligatory gallery: http://www.iki.fi/leopold/Photo/Galleria/
 
The Bigma at 500mm is a f6.3 lens though it somehow tells the camera it is f5.6 allowing autofocus!
 
My 5D2 easily focuses at f8 and sometimes higher in bright sunlight.
 
wkay said:
My 5D2 easily focuses at f8 and sometimes higher in bright sunlight.
Click to expand...
If you are just talking about setting it to f8 then that means nothing since the camera opens the lens wide open while focusing.

--
When the going gets weird, the weird turn pro. - Hunter S. Thompson.
 
Get the 1.4x TC instead. Works great with the 5d2 and 70-200 f4. I used this setup at the zoo a few weeks ago and loved the results.
 
Argh,

I fell into the "someone answers a question being made a year ago" trap. So, recommendation to all: before using your time for replying, please check the age of this thread first.

Kind regards,
  • Henrik
--
And if a million more agree there ain't no great society
My obligatory gallery: http://www.iki.fi/leopold/Photo/Galleria/
 
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