Which will have better autofocus?

Hi all,

I posted this thread on the Fred Miranda forums, but multiple opinions are great too:First, thanks for reading and second, please read the entire post before simply saying that one option is better than the other.

My question: Which has better autofocus for shooting high school sports under both reasonable and sometimes professional sports lighting?

The choices: The 40D or a 1D Mark II WITH a 1.4x teleconverter. Either camera will have a 300 2.8, resulting in a similar field of view with either one. I do NEED the length created by 1.6 x 300 or 1.4+1.3x300 to get a tight shot at the XCEL Energy Center. If anyone can think of better choices, excluding the bank breaking Mark III, be my guest.

Past experience: I've used my 20D successfully for both college hockey and high school. The AF sometimes misses, but the most annoying part is that the 20D plus 300 2.8 is too tight for most Minnesota high school rinks, and the 20D doesn't reach a true 5 FPS while using autofocus.

The solution: That's why I posted here! I've been favoring the 40D simply because I don't really "need" 8.5 FPS and the autofocus would be center point only with the converter, per my understanding.

ng.

Believe it or not, 40d without extender will be faster, 1dmkii with extender will likely be more accurate. If you are shooting nighttime stuff/indoors, go for aperture, not focus speed, since that is what will improve your keeper rate more.

basroil wrote in post #7383166
Believe it or not, 40d without extender will be faster, 1dmkii with extender will likely be more accurate. If you are shooting nighttime stuff/indoors, go for aperture, not focus speed, since that is what will improve your keeper rate more.

Also noting, like you mentioned, that conditions at the professional arena will allow the 40D to be used at f/4 if I so choose, but that won't any effect on the aperture during focus.

My experiences disagree with Basroil's.
The MkII with that fast f/2.8 an a T-con will not drag the AF down to being slower than the 40D.
Likely he shot more sports than me though, so take my statement with appropriate salt. Out in th wild, it seems the MkII and T-con will definitely be the winner all around with that optic.


Agree that speed aside, you will get better more consistent results with the MkII combo as well.
Plus you get that advantage you mention, being able to remove the T-con for when you need less focal length.

CyberDyneSystems wrote in post #7383215
My experiences disagree with Basroil's.
The MkII with that fast f/2.8 an a T-con will not drag the AF down to being slower than the 40D.
Likely he shot more sports than me though, so take my statement with appropriate salt. Out in th wild, it seems the MkII and T-con will definitely be the winner all around with that optic.


Agree that speed aside, you will get better more consistent results with the MkII combo as well.
Plus you get that advantage you mention, being able to remove the T-con for when you need less focal length.

In most cases yea, the 1dmkii will be faster, especially with an IS lens with IS on (11.1V vs 7.4V, 11.1V wins hands down). In nighttime stuff though, I find that a 300 2.8+1.4 on my mkiii (which i have tried only once, since iso6400 is not pretty), the performance takes a huge hit. Daylight and even into sunset it's fine, but once you need to start pushing iso3200 to get 1/500 f4, then you run into problems. And overhead lights cause more ca with the extender, which will likely be an issue if the distance is large enough to justify a 420mm lens.

HuskiesD1 wrote in post #7382987
The AF sometimes misses, but the most annoying part is that the 20D plus 300 2.8 is too tight for most Minnesota high school rinksng.

If I read this right, you will have the same issue with the 40D having the same 1.6 crop factor as the 20D. If so, then the MKII would give you a little relief here and great AF performance.

The 300 2.8 with 1.4x TC will give you a 420mm f/4.0 lens. On the XXD series, the center AF has a special "high precision" mode that is enabled when using f/2.8 or faster lenses. If you use the 300 f/2.8 & 1.4x TC, then this high precision mode can't be used, as there is not enough light.

On the 1D series, they too have a "high precision" mode. However their high precision mode is activated with lenses f/4.0 or faster. That means that the 300 f/2.8 with 1.4X TC on the 1D MKII will be able to use the high precision sensors, and thus give you better AF.

The net result is that the 1D MKII should have much better AF with the 300 f/2.8 & 1.4x TC than the 40D.