AF Problems....

Jay42

macrumors 65816
Original poster
Jul 14, 2005
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I took a bunch of pictures at Saturday's Red Sox game with my Canon Rebel XT and a 80-200 f/2.8L. I would say a majority of my pics were out of focus and basically worthless. It seemed that the camera wanted to focus behind the players. Is this because of the bright white uniforms? Would MF have helped.

Settings: f/2.8 on Av, ISO 800-1600, Servo AF and One Shot AF.

One decent picture:
 

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Abstract

macrumors Penryn
Dec 27, 2002
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I don't understand the question, really.:confused: I can't even see whether the batters are in focus because it's difficult when looking at small photos.

Did you have a monopod or tripod? Are the players out of focus because they're moving? When looking at the full sized photo,are the batter's shoes or the catcher behind the batter out of focus? THey don't really move nearly as much as a batter.

If I were to focus, I'd probably just focus on the catcher or on the ground where the player is standing, then just do a focus lock. If I knew I wasn't getting out of my seat, I'd switch my lens to manual focus so that my camera never has to focus on the batter again. If focusing on the ground or shoes doesn't work, then the catcher is probably around the same distance away from you as the batter (ie: at infinity). After that, you'd still need a monopod or something.
 

Jay42

macrumors 65816
Original poster
Jul 14, 2005
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The unforgiving depth of field at f/2.8 was certainly part of the problem. I did not have a monopod or tripod with me. Would this have helped at shutter speeds of 1/1000 and above?

EDIT: OK, maybe not
 

ChrisA

macrumors G4
Jan 5, 2006
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Redondo Beach, California
Jay42 said:
The unforgiving depth of field at f/2.8 was certainly part of the problem. I did not have a monopod or tripod with me. Would this have helped at shutter speeds of 1/1000 and above?
If you are shooting at 1/1000 camera shake would not be that much of a problem at 200mm. At f/2.8 and 200mm the depth of field is quite is reasonable if we assume the subject is 100 or 300 feet away. (you have 10 to 30 feet of depth)

It is hard to say what is wrong without seeing the images. One guess is that you are leting the camera pick the auto focus spot and it is picking some foreground object like grass in the outfield or a fan in the stnds. That is the major problem with autofocus the camera can't know what it is you want in focus. You should be able to select the focus bracket.

One idea would be to lock the focus on home plate.
 

ChrisA

macrumors G4
Jan 5, 2006
11,609
408
Redondo Beach, California
Jay42 said:
The unforgiving depth of field at f/2.8 was certainly part of the problem. I did not have a monopod or tripod with me. Would this have helped at shutter speeds of 1/1000 and above?
Is DOF really that unforgiving? I think you should have at least 10 feet of depth if you were 100 feet from the subject. More depth if you were farther away.
 

Mike Teezie

macrumors 68020
Nov 20, 2002
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Depth of field isn't your main problem here. You can get sharp images with 2.8 at that focal length all day long.

Are using a weighted focus point? My hit rate is much, much higher when I force the camera to focus where I want it to, rather than let it guess what I want. For these shots, with an XT, I'd weight it to right most point:



That way, when you turn the camera into portrait orientation, your focus point should be right around the player's head. I would focus wherever you wanted on the the player before the pitch, recompose, and when he swung, press the shutter button. You'll get a much higher successful hit rate using this method.

Or, set it to the far left point, focus on the player before the pitch, then recompose to where the player is in the bottom right corner, and you can see the massive crowd of people watching in the background.
 

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extraextra

macrumors 68000
Jun 29, 2006
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f/2.8 isn't that unforgiving. I can get accurate focus with f/1.4 with things pretty far away.

I'm with the poster above. (btw, your website and photographs are amazing!) If you didn't choose a specific focus point and had all 7 enabled, then the camera will just pick whatever one it thinks is best.
 

Abstract

macrumors Penryn
Dec 27, 2002
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Jay42 said:
The unforgiving depth of field at f/2.8 was certainly part of the problem. I did not have a monopod or tripod with me. Would this have helped at shutter speeds of 1/1000 and above?

EDIT: OK, maybe not
Ok, nevermind. I didn't know the shutter time was set so quick. :eek:

It's really just how you focused then. If you can't focus on the player, then focus on the catcher. They're close enough together that you don't need to worry about one being in focus and the other being out of focus (depthwise).

I don't think f/2.8 is an issue at 200 mm, so again, if you focus to home plate, or even to the catcher, just switch to manual focus after AF has done it's thing correctly, and just never let AF refocus. You'll have a higher success rate if you focused correctly once and kept that constant. Or manual focus and don't refocus.
 

sjl

macrumors 6502
Sep 15, 2004
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Melbourne, Australia
extraextra said:
f/2.8 isn't that unforgiving. I can get accurate focus with f/1.4 with things pretty far away.
(Emphasis mine.) I don't think that that's particularly hard. f/1.4 implies a relatively short lens (Canon only makes lenses that fast at up to 85mm; longer than that, and you're looking at a smaller relative aperture). In turn, that suggests that the infinity focusing distance is not all that far away - my 17-85, for example, has the infinity mark just past 10 metres.

So if the object is, say, 20 metres away, and you're shooting at f/1.4, I'd suggest that the lens is more likely than not focusing to infinity ...