How to choose AF elements in EOS

[Swimmer]

I was trying to choose the center AF element and temporarily disable the others. I don't have the manual with me, but by following the instructions given, I wasn't able to accomplish this. Any advice?

Also, when you accomplished DSLRer's go into the woods, with out a set subject in mind, what are your typical initial camera settings? Do you use "Av", with the two f-stop brackets? I've been experimenting with the "P" and manualy setting the f-stop for DOF and manualy setting ISO.

[mcary]

For the first question, I'm assuming it depends on which EOS camera you have. I have the Rebel XT and my focal point button is in the upper right hand corner on the rear of the camera. The symbol above it looks like the arrangment of the seven focal points inside a box. Push this button and then use the scroll wheel near the shutter button to select between focal points(indicated by red dot). When finished selecting just hit the button again or push the shutter button half way and it will exit with the AF point you chose.

As for walking the woods. I usually use the AV mode and set the lowest f-stop possible (largest aperture) for the lens in hand (because I am trying to be ready in the instance of sudden fast moving wildlife). This leaves you with the fastest shutter speed possible under current light conditions in order to "stop" the action. If the camera's highest shutter speed can be acheived at a higher f-stop (really bright day), then I will adjust up to that f-stop to allow for more DOF. This is just my personal preference.

Almost forgot! I also choose the AI servo autofocus function in order to track the critter as it moves. Also tend to use the 400 iso setting to gain a compromise between shutter speed and image quality.

[Steve Foss]

Swimmer, here's how to select focus point with the 20D/30D. Make sure the camera is on and awake. Press the button on the upper right of the camera back. There are two buttons there, so pick the right-hand one. Then, while looking through the viewfinder, spin the control wheel on the camera back until the AF point you want is lit, and then just press the shutter half-way down to enable it. To change it back, repeat the process.

Here are my kick-around settings. Some are those mcary uses, some are different.

1. Av mode (aperature priority) — Like mike, I want my aperature as wide open as possbile to give myself the best chance at capturing a grab shot when something unexpected happens. Widest aperature means fastest shutter speed. And my lens is slow at f5.6 at 400mm, so I always want the aperature wide open unless I'm in a setting where I can slow down and make adjustments.

2. Iso400 — Because my sensor and image processor are so good at controlling noise, 400 is the best settting for all-around shooting, offering me the greatest chance I'll have a fast shutter speed when I need it while preserving image quality. I have made 20x30 prints at iso400 with the 20D, and they are sharp and full of color subtlety. Most of my grab shots come from the truck along the Echo Trail, which usually involves looking into the woods, so even on a bright day I leave it at iso400 because I can't be sure my grab shot won't involve deep shade. If I'm out in a boat on a lake on a bright day or some such thing, only then will I drop iso to 200 or 100 for off-the-cuff shooting. Again, if the situation allows me to slow down and work for some time with a subject, I'll adjust iso as low as possible. If I had the 400 f2.8 on all the time, I'd still leave it at iso400 but would be far more willing to drop iso than with the f5.6.

3. One-shot focus mode — Because I almost always lock focus on the subject and then recompose before hitting the shutter, I avoid the Al servo mode unless the critter is on the move toward or away from me. I find Al servo sometimes causes the lens to hunt for focus on a fairly still subject, even with prime glass occasionally, and I can miss the shot I want because the lens is hunting.

[Dbl]

Another quick tip from the sports guy, you select your focus on the back right button and then PUSH down on the joystick button. This will select center point only focus, if you PUSH again on the joystick you are back to all points focus. This is faster and easier then the scroll wheel, you don't have to remember which way to turn the wheel. I use this all the time to get better focus lock with changing conditions. If you want something other than center or all, then use the method Steve describes. I use the exact same settings Steve does on the other features (AV, ISO 400, etc).

[mcary]

I have also noticed the focus "hunting" in the AI servo mode that Steve mentioned. The Rebel XT is the "bottom of the line" dSLR so to speak and I wasn't sure if that was a function of the camera or if it was normal throughout Canon's line. On that note, a side question for you guys out there. Have any of you had the opportunity to use the 20D or 30D vs. the Rebel XT in AI servo mode? I would be interested to know if there is a noticeable difference in the capability of the autofocus.

[Steve Foss]

The 20D/30D autofocus is somewhat better than the XT. The "1" series cameras have phenomenal autofocus. It's also a function of the lens. Inexpensive lenses generally don't operate as fast as Canon's USM lenses. And then there are differences within Canon. The non L lenses tend to be a bit slower, in my experience, and there's some variation within the L series. My 100-400L on the 20D is fast, but is noticeably slower than the lightning fast combo of the monster and hugely expensive 400mm L IS f2.8 I shot on the 1D MarkIIn for awhile last winter.

While I'm confident in the 20D autofocus, the 20D/30D offers a higher-precision autofocus capability when using lenses that open to f2.8 or wider.

The XT is a vast improvement over the original Digital Rebel's autofocus system. It looks like Canon will announce later this year a 400D Rebel XT upgrade (the Rebel XT's designation is 350D). The word is it'll be about as incremental an upgrade as the 20D to the 30D was. Word is Canon won't announce a new "1" series body this year, but is planning to offer an upgraded 1Ds MarkII next year with a 22 Mp sensor and increased burst rate of 5 to 8 fps (the current rate is only 3 fps on that camera), among other improvements.

[Swimmer]

Thanks guys. Dbl, that does sound handy...using the joystick button for quick center focus and back...I knew there was a quicky somewhere for that function. On a side note, I read the horrible reviews for the outfit that I ordered the camera from...of course, AFTER, I ordered the camera (and here I am thinking I'm a savy consumer!). I guess I was somewhat lucky in that I ordered enough bait and switch items that I received everything promptly and in A-1 shape...others who refused any ad-ons were then told the camera was out of stock and subsequently had difficulties canceling their orders. In hindsight I would use B&H, although searching their prices and compairing with the ad-ons I did want/order the price was about equal. That being said, customer service and reputation certainly count for something...especially when this outfit that I ordered from gets shut down by the NY Attorny General (a possibility)! I also called USAA VISA and informed them of a fraud concern, so we will be watching...

Steve, I ordered an 18ma battery from SterlingTek...very good value and fantastic service/shipping.