Luminous Landscape Forum

Equipment & Techniques => Cameras, Lenses and Shooting gear => Topic started by: Jeremy Roussak on February 23, 2009, 04:33:45 am

Title: 5DII autofocus
Post by: Jeremy Roussak on February 23, 2009, 04:33:45 am

This is probably written down somewhere, but I can't find it.

Will the 5DII autofocus work with a 100-400L and a 1.4TC?

Jeremy

Title: 5DII autofocus
Post by: francois on February 23, 2009, 04:43:05 am

Quote from: kikashi

This is probably written down somewhere, but I can't find it.

Will the 5DII autofocus work with a 100-400L and a 1.4TC?

Jeremy

I believe that only 1Ds/1D bodies will focus (AF) with the 100-400 + 1.4x extender. It would give you a f/8 and 5D can only autofocus up to f/5.6.

Edit: it might be possible to autofocus if you tape the contact pins on the lens but AF will be really slow.

Title: 5DII autofocus
Post by: Ronny Nilsen on February 23, 2009, 07:04:55 am

Quote from: francois

I believe that only 1Ds/1D bodies will focus (AF) with the 100-400 + 1.4x extender. It would give you a f/8 and 5D can only autofocus up to f/5.6.

Edit: it might be possible to autofocus if you tape the contact pins on the lens but AF will be really slow.

Taping the pins will not solve the fundamental problem that at least part of the AF senors will not be able to "see"
out of the lens because the spacing of the sensors demands at least a f/5.6 opening. The AF of the 1D cameras
have better sensors that are closer spaced (and compensate by being more accurate) to be able to give AF with
only a f/8 opening.

See the Phase detection (http://en.wikipedia.org/wiki/Autofocus) section to understand why taping the pins will not work reliably.

Ronny

Title: 5DII autofocus
Post by: francois on February 23, 2009, 07:19:32 am

Quote from: ronnynil

Taping the pins will not solve the fundamental problem that at least part of the AF senors will not be able to "see"
out of the lens because the spacing of the sensors demands at least a f/5.6 opening. The AF of the 1D cameras
have better sensors that are closer spaced (and compensate by being more accurate) to be able to give AF with
only a f/8 opening.

See the Phase detection (http://en.wikipedia.org/wiki/Autofocus) section to understand why taping the pins will not work reliably.

Ronny

Ronny,
I didn't say that taping the pins would produce reliable AF performance. Even on my EOS-1 bodies, a 100-400 + 1.4x extender produces slow AF and the accuracy is average at best. On top of that, I'm not sure that mounting a 1.4x extender on the 100-400 is really useful (speaking of IQ).

Title: 5DII autofocus
Post by: Jeremy Roussak on February 25, 2009, 03:45:40 am

Thanks. I think I shan't bother with the extender.

Jeremy

Title: 5DII autofocus
Post by: francois on February 25, 2009, 04:12:03 am

Quote from: kikashi

Thanks. I think I shan't bother with the extender.

Jeremy

Jeremy,
The 1.4x extender works fine with the 70-200 (f/4 or f2.8) but I wouldn't buy it as "companion" for the 100-400 only.

Title: 5DII autofocus
Post by: Jeremy Roussak on February 25, 2009, 01:07:19 pm

Quote from: francois

Jeremy,
The 1.4x extender works fine with the 70-200 (f/4 or f2.8) but I wouldn't buy it as "companion" for the 100-400 only.

Thanks - I'll think about that, as the 70-200/4 is on my list of lenses to buy (along with the 85/1.8; I have the 24-105/4). I'm hiring the 100-400 for a holiday on which I hope to see some tigers and I was just wondering if I'd get decent performance with the 1.4x. It seems not, and I think in reality I probably don't need it, given the resolution of the 5d2.

Jeremy

Title: 5DII autofocus
Post by: mahleu on February 25, 2009, 02:10:27 pm

Quote from: kikashi

This is probably written down somewhere, but I can't find it.

Will the 5DII autofocus work with a 100-400L and a 1.4TC?

Jeremy

According to Canon it will (in one of their brochures)

Title: 5DII autofocus
Post by: scubastu on February 25, 2009, 04:44:56 pm

Quote from: mahleu

According to Canon it will (in one of their brochures)

No it won't. It will only AF with an f5.6 or faster lens, you'll need a 1 series body to AF with an F8 equivalent.

Title: 5DII autofocus
Post by: francois on February 26, 2009, 02:43:48 am

Quote from: scubastu

… you'll need a 1 series body to AF with an F8 equivalent.

And AF will only use the center point.