Auto Focus What to do??!! ahhh

Tristen, can you tell us your technique for gaining auto-focus ... step by step, what exactly are you doing?

Most often a focus problem is technique related and has nothing to do with the camera. For example, if the DOF is quite shallow I've seen people miss shots because they sway ever so slightly forward and backwards after focus lock but before they take the shot. Because of this I'd recommend taking some shots

1. using the center focus point only
2. of a stationary object
3. using a tripod

before coming to the conclusion that the camera is at fault.

Also remember that the actual area of the focus sensor is larger than the little red box in the viewfinder; the camera will AF on whatever has the most contrast in the area covered by the sensor, which may not be where you thought it was. When you eyeball the focus you know what you're looking at. There's a "standard" focussing test that's been discussed at length here. It uses a printed form with a discrete aiming point so there's no confusion about where you're focussing. If you think the camera's misfocussing, run that test and see what it looks like. You may just not be choosing a good-enough focussing target for your camera.

Yeah I am gonna take it back this week and see if they can they can also see the problem. If they cant I will send it to canon. Hopefully they can find something wrong if not I will most likely just cry lol. I made 3500 dollars last year spent 1400 on 20d LOL I was hoping it would perform like it should.

Forget about all these lip and ear crops. Use this test. It'll work for a 20D, just follow the instructions. The test will eliminate human error from the equation.

Here is another example from today I dont know why I keep testing it I guess I am hoping to be wrong.

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You aren't going to be able to get consistent results at 1/100 s. @ 300mm. Get a tripod and do a real focus test.

Ok ill be back later with tripod results.

Keep it simple, use this test setup: http://www.focustestch​art.com/chart.html

WELLLLLL>>>>>..

Turns out im an idiot. I finally figured out what I was doing wrong. Here it goes. I took a trip to the everglades couple weeks ago and came back with great shots of gators and birds and friends however they all were just a hair out of focus. Well what I was doing was focusing on the subject then waiting about half second or longer for the right pose or moment etc in that little time frame I could have leaned or something a tiny little bit causing my pics to be out of foucs.. Some above pointed that out to me THANKS! Any way I used a tripod and manually focused and auto focused and I didnt find any flaws.... Sorry guys LOL I was wayyyyyy wrong. O well Thank you so much for your advice!!! Now I need another trip to Florida!

The good news is there is nothing wrong with your gear.

Thanks for sharing. I will try to remember this lesson when in Yosemite in May and Alaska in June.

Tom_D; just remember mountains don't move much between focusing and composition

for Tristan; maybe you should try what others here on the board do and use the custom function to move focusing to the * button. This will enable you to focus independently of releasing the shutter.

My brain is hard wired for the half press full press thing; but others swear by it.

Good luck.

-TommyD

Mite give that a try too thx!

What is a good shutter speed for hand holding @ 300mm? I mean what if I get a nice chance at a hawk again and dont have a tripod in nice lighting conditons? Obivously 100 is to slow because I have gotten back soft shots.

1/(focal length * crop factor). Though that is just a general recommendation. Some "crop factor crazed lunatic" may post a different formula .

EDIT: Fixed bad brackets.

This is really most useful when you are locking exposure in Av/Tv/P modes or metering for highlights using partial metering. You can meter/AE lock, recompose, lock focus, release shutter. Sounds weird, but it worrks. In other situations with I like it all on one button, with the option to use AE lock on the * button.