I have always used center point focus, where it'll always focus on the center of the frame, using the *, set in the custom fuctions. that way i can recompose after center focusing.

However, with tonight's bball game, I spoke with another one of the photographers, who shoots for the hartford courant, and since I had been wondering about the tracking focus, by selecting all focus points.. i decided to ask him to explain it a little to me. He says it will initially focus in the center first, then as you continue to hold down the focus button, it will track the object around the other focal points in the frame.
I tried this tonight without too much luck. It did work, but I found a lot more photos out of focus than when using center weighted. He told me that center tends to be a bit quicker and sharper. However, I am using a 30D, vs their 1D's... and I have many less focus points...

Any input on this guys? TIA! =D

That's the way AI Servo works in Canon cameras. It always starts with center (unless you have a specific point selected) to acquire focus and then "hands" the subject to the other pints as the subject moves across the frame.

And of course a 1-series will track much better than a 30D. More focusing points, more sensitive points, better focusing algorithm, etc...

where the 30D and 40D likely do not.

Fast lenses track a lot better than slow ones. 30D's outer focus points are unfortunately not very sensitive and easily fail to lock on target in low light. I've gotten a lot more reliable results with just the center point.

One thing you might look at to improve the tracking...not sure if the Canon bodies have this.. With Nikon it's called <b>Focus Tracking with Lock-On</b> (used to be AF Lock-On). It allows you to set the time duration the AF delays reqcquiring a new subject that passes between you and your original subject. It's especially useful in team sports.. Say you lock on to one player traveling down court.. As the action moves, other players come between you and your first target. With AF Lock-On in the off position, the AF system will immediately lock on the new target that has entered (or just passed through) your AF point, loosing acquisition of the first, intended subject. If you set AF Lock-On to On, (Nikons have three delay settings) there is a slight delay applied before the AF system releases the first subject and locks on to the new.. I find this of tremendous value.

Also, does your body have an AF-On button?

Long ago I adopted the AF-On only for focus and decoupled the focus activation from the shutter release. When coupled with AF-C (continuous AF) you have best of all worlds of Auto-Focus.

Press the AF-On button and hold and you have continuous AF as though you half-pressed the shutter release in AF-C mode. Press and release the AF-On button and you have the same as in AF-S mode. You can lock focus without touching the shutter release.

I find this most useful for action/bif's/sports shooting where I want to have AF-C, but may, in an instance might need or want AF-S to be able lock and recompose. Also very useful with perched birds where a wind blown twig or branch would send AF haywire..when combined with the AF Lock-On feature above, focus becomes much more accurate.

Sometimes it worked and sometimes it didn't.

I recently went to the Denver Aquarium with my kids. I messed around with the focus tracking feature. Something I almost never use. But what the hey, I'll try it. It seemed to work better on the larger fish in these images. The small orange and purple fish gave it a hard time. As well as the multiple fish tank with the little boy in the background.

<a href="http://s274.photobucket.com/albums/jj277/ChasWG/?action=view&current=9lineGrouper.jpg" target="_blank"><img src="http://i274.photobucket.com/albums/jj277/ChasWG/9lineGrouper.jpg" border="0" alt="9 Line Grouper"></a>

<a href="http://s274.photobucket.com/albums/jj277/ChasWG/?action=view&current=9lineGrouperCU.jpg" target="_blank"><img src="http://i274.photobucket.com/albums/jj277/ChasWG/9lineGrouperCU.jpg" border="0" alt="9 Line Grouper CU"></a>

<a href="http://s274.photobucket.com/albums/jj277/ChasWG/?action=view&current=EyetoEye.jpg" target="_blank"><img src="http://i274.photobucket.com/albums/jj277/ChasWG/EyetoEye.jpg" border="0" alt="Eye to Eye"></a>

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<a href="http://s274.photobucket.com/albums/jj277/ChasWG/?action=view&current=Boyinthetank.jpg" target="_blank"><img src="http://i274.photobucket.com/albums/jj277/ChasWG/Boyinthetank.jpg" border="0" alt="Boy in the Tank"></a>

I'm thinking the focus sensor got really confused with all those fish darting about. Then I saw the boy walk behind the tank and I just reacted. And in the orange fish pic the glass was really scratched and all sorts of junk floating in the water didn't help. Plus it is only a couple of inches long. Maybe size goes matter. ;)

Fish usually move so erratically that it's practically impossible to track them with AI servo (esp. small fish darting around). AI servo works well with subjects that are moving towards you or away from you at constant speed. Fish are swimming back and forth - and usually without any predictability. Combine that with dirty&amp;scratched tank glass and it's pretty much mission impossible for AI servo, I'd say. It's very difficult to shoot fish in any focus mode :)

This is certainly a case where the Lock-On delay would be very useful.. as one fish passes between you and the intended target. Or, a child passes between you and the tank. As long as this rogue target passes between you and the active AF point, you are vulnerable to the release of the first target and acquisition of the new.

It's just another layer of "filtering" going on to add to the unsharpness of some of the images. In the images of the larger fish, they where moving slowly and basically right at me.
The last one the tank was round, so the curved glass was going to mess with anything at the edges no matter what. It was always going to be an artsy-fartsy shot anyhow.

instead of car mods! I'm all messed up now. What to do, get a 30D or RS6 exhaust? New lenses or turbos?

What's a boy to do???!!!

but yeah, it would lose track sometimes. but I do see it being an improvement when players run across the lens when i am focusing to say the 3pt perimeter. whereas with the center focus it would try to focus out and need to focus back in very quickly.

I also use the D200 when i need the 300mm 2.8
so I am aware of the AF-on, etc.
However I need to look to see if there is a re-focus delay, as this would definitely prove useful. Maybe someone here knows?

I do use the seperate AI-servo focus button away from the shutter release. And yes, I agree, it is very beneficial in single lock on focus and recomposing as well as continuous tracking of the focus. Thanks

lenses hold their value much better than cars do, and in my case, lenses will also probably last longer than my car is going to at this point =p.

My camera equipment now worth more than my car... =\

how my settings were set. But yes, my 70-200 2.8L focuses MUCH faster (and quieter) than my 50mm 1.8 =p USM FTW

<img src="http://pictureposter.audiworld.com/123384/jellyfish.jpg">

ive spent more on camera stuff than i did buying my A4 ($6500) lol

If there's enough light and contrast, the outer AF sensors work reasonably well, but in dark and "flat" conditions the 30D is struggling with the outer sensors. In these conditions I prefer to track with the center focus point only. Obviously then there's not much margin for user error like you said. Luckily the 70-200/2.8 is a very nice lens to work with. 200/1.8 would be pretty sweet, though :)

I also shot the Jellies at the Denver Aquarium, but I didn't have too much luck this time.

But I did catch this guy! He was "moving" but I had to use a hour glass to time him.

<a href="http://s274.photobucket.com/albums/jj277/ChasWG/?action=view¤t=StarfishlowtideOrcasIsland.jpg" target="_blank"><img src="http://i274.photobucket.com/albums/jj277/ChasWG/StarfishlowtideOrcasIsland.jpg" border="0" alt="Photobucket"></a>

Oh, obviously there was no glass, but an old PS camera.

This has turned into some sort of internet fish fry!

So obviously this isn't in the same arena as the 30d, 5d or 1DmkIII. I just thought I'd through in my experience with what I did recently.

I has happy with the results, but know there is more to be had with a much better body.

but inside wise... not so much =(
but still comes out with great photos

I gives it a verticle release button and control also. Deffinently wieghs it down, but I like it.

love it