40D AF Disappointment

[Lucio Gomes]

I finally had a chance to take the 40D down to the beach to do some shooting
with my 500mm f4L IS. I have to say it was disappointing at best, and I am definitely
not selling my 1D MkIIn for a while.

Canon's much touted "improved AF" did not deliver!
The AF was very "nervous" when I tried to follow a foraging sandpiper, much
like the 30D was; throwing the focus out a little too quickly whenever I wasn't dead-on centered on the bird. The MkII's AF tracking sensitivity can be set to react slower when focus tracking, thus minimizing the "nervous" reaction of the camera's AF, and you can expand the focusing points to help you "stay" with the subject longer. With the 40D, If you don't keep the AF rectangle right on the subject, the AF will immediately shift. Of course, a small sandpiper is not exactly an easy subject to follow, but the MkII would have done a much better job - I know because I have a MkII and have shot many a foraging shorebird with it - at keeping the subject in focus.
The worst part, though, was when I attached the 1.4x and tried shooting a green heron in flight, then
a belted kingfisher flying around against a blue sky. The lens would hunt, miss the subject, then
stay stuck at infinity and I would miss the opportunity altogether. It wouldn't even try to re-acquire focus when I lifted my finger off the shutter and then pressed it again; and yes, I did have CF III set at "0" to enable focus search. Even on occasions when I "knew" I had the rectangle ON the bird, it would shift focus to the background way too easily. Trying to activate all focusing points to shoot a bird in flight was a waste of time!

Maybe it's my particular 40D, but I am not impressed by the new AF. It is quick to acquire focus in one shot AF, but who needs that? They are all fast in One Shot!
The AF seems very fast and tracks much better with my old 300mm f2.8L and with the 70-200mm f2.8L, but I really bought this camera to use with the 500mm and the 1.4x tc (f4 and f5.6 respectively) to shoot mostly birds.
On the bright side the frame rate is great; I actually played with the Live View and had a blast; the shutter noise is awesomely quiet; and the image quality is impressive.
I guess I am comparing apples and oranges here, so I can't really blame Canon or bitch too much about the camera's AF; it is a "prosumer" after all.

I'm keeping my 1D MkII for now.

If anyone has had similar experiences, or hopefully better, please post a comment.


Lucio

 

[Brian Lowe]

Hi Lucio,

Sorry to hear you are disappointed with the 40D AF. So far, I am very happy with my 40D and the AF and I find it a perfect addition to my 1DMKIIn.

One thing you may want to try with a long lens, set CF III number 1 to 1: "Focus search off". This prevents the camera from becoming grossly out of focus as it attempts to focus again. Especially convenient with super telephoto lenses which can become extremely out of focus.

This weekend I was testing my 40D with my 100-400L and the AF was fast and tracked just fine.


Brian

 

[Nikolai Sklobovsky]

One thing you may want to try with a long lens, set CF III number 1 to 1: "Focus search off". This prevents the camera from becoming grossly out of focus as it attempts to focus again. Especially convenient with super telephoto lenses which can become extremely out of focus.

Totally. That was one of the first one I disabled

 

[Deleted member 55]

RE: AF hunting

Hi all.

You also need to remember that the AF sensors on the 40D are not contiguous and there are holes between them that are not there on the 1 series.

Also the ability to turn off AF hunting is a first on the 40D for a non 1 series cameras.

Turning off AF hunting is not just for long lenses. It is very helpful in extreme low light as well as in any low contrast shooting condition where the subjects will never have a large difference in focus distance.

 

[Nill Toulme]

Be careful with turning off focus hunting. IMO this is one of those "fad tips" that gained currency over the last year since AM first "discovered" it. I even vaguely suspect it might have a lot to do with many of the AF "problems" that get reported.

I tried it on a 1-series body for half a baseball game until it caused me to miss a home run shot because, well, the focus refused to hunt enough to AF on the player. I switched it back to the default and have left it there.

Nill
~~
www.toulme.net

 

[Nikolai Sklobovsky]

Be careful with turning off focus hunting. IMO this is one of those "fad tips" that gained currency over the last year since AM first "discovered" it. I even vaguely suspect it might have a lot to do with many of the AF "problems" that get reported.

I tried it on a 1-series body for half a baseball game until it caused me to miss a home run shot because, well, the focus refused to hunt enough to AF on the player. I switched it back to the default and have left it there.

Nill
~~
www.toulme.net

Nill, good point.
And the good news: that's what you can use your new User Settings are for. Have one with AF hunt ON, another one with it turned OFF, and switch in a flick

 

[ChrisDauer]

I guess I am comparing apples and oranges here, so I can't really blame Canon or bitch too much about the camera's AF; it is a "prosumer" after all.

I'm keeping my 1D MkII for now.

If anyone has had similar experiences, or hopefully better, please post a comment.

Yeah, I would think apples and oranges. Coming from the 20D, it's a HUGE improvement. About a 33% (maybe 25%, it's hard to say) improvement over the 20D. I would be shocked (and probably a little dismayed) if it surpassed a 1D2n; a professional camera, which when used sells for more than twice the cost of a brand new 40D.