AF question? Just when I think I have it figured out.

Hey everyone,
I shoot with a 40D, 24-70L and an 85 f/1.8 (for the portraits that I'm talking about here.) I'm trying to figure out why I'm continually having soft pictures. I think exposure it part of the problem. I just can seem to get consistently sharp images. I've been trying to figure out what I'm doing wrong. I got thinking about my AF setting and wondering if that could be part of the problem. I've been shooting in one shot mode. I set focus and meter on the eyes of the kid closest to the middle of the pic, and then recompose the shot. Of course kids are always moving a little bit, but I'm never below 125th and try to stay above 6.3 on my aperture. And I feel like I can't trust my camera's light meter. It just seems like things that should be consistant aren't. Does anyone have any insight for me? This is a link to my blog where you can see what I'm talking about. www.federkeil.blogspot​.com

I can't see anything on the blog that you are talking about here.

Focus recompose can create problems with wide apertures at closer shooting distances. You can use the nearest focus point instead.

OK, I see some of the pictures on your blog are not sharp. Could be lens, camera or the technique. You should be getting quite sharp shots with 85mm f1.8. I have one and it is very sharp. Are you softening some of these shots? I was looking at a shot of a kid in snow and his face looks like softened in pp.

Post some of the pics you are talking about so we can help.
I don't want to have to go to YOUR blog and them come back here to give you my help.
My guess is that no one else does as well.
Make it easy for us - you do the work, not us.

Well Michelle, FWIW I have the same frustrations. Although I'm often pushing the wide aperture, which exacerbates the issue. An experienced shooter I know is giving up Canon and going to the dark side because Nikon's AF capability is apparently much better.

Have you tried testing your lenses for front focus/back focus? You might want to check out www.focustestchart.com. It's a pretty simple test and you can benchmark all your lenses in a half hour or less.

Your photos are great, by the way. Holy cow, those Barnsons are productive.

I'm going to butt in here and ask a stupid question that I can't figure out on my own. I have a 5D, when I focus, little red square shows up, and I keep the shutter button half pressed and recompose? After I take the shot, the little red square does NOT show where I first focused, but on the new spot I recomposed to. Am I saying that right? Why wouldn't that little square stay where I first focused it? I do One Shot, I read that AI Servo doesn't let you recompose with half press. Anyone know? I've been practicing on a mannequin head, and with her plastic painted on eyes and plastic skin, its really hard to know if I've nailed the focus for sure or not.

BeckyMax wrote in post #9753835
After I take the shot, the little red square does NOT show where I first focused, but on the new spot I recomposed to.

The position of the 9 red squares (Auto focus points) are fixed relative to your camera's sensor. You only have 9 of them, and you can only auto focus on something that's behind one of those 9 targets. If your camera moves (relative to the subject, or vice versa) between the moment you trigger AF and the moment you trigger the shutter, then the AF highlighted in the captured image is not going to be in the same place. Your camera has no way to track the actual object that you targeted and chase it around with a floating AF target - that is, unless you're in AI Servo and the subject moves from one AF target to another (this works better when your camera has a bazillion AF targets, like the 1Ds Mark IV). Even then, the individual AF targets are not moving, the camera is just jumping from one to another.

Advice I always get, if you want the best autofocus performance, is to avoid recomposing - just take the picture a little wide, keep the AF target on the subject, and crop to taste later.

Hi. The shots look like they have been worked on. convert a negative to jpeg to show what we are up against, and take a shot of an adult above the age of 35. light looks nicely diffused on the softer shots but to harsh on some of the others. either way the shots are still sellable.

BeckyMax wrote in post #9753835
when I focus, little red square shows up, and I keep the shutter button half pressed and recompose? After I take the shot, the little red square does NOT show where I first focused, but on the new spot I recomposed to. Am I saying that right? Why wouldn't that little square stay where I first focused it?

Because it is simply showing which focus point was used, not where you actually focused. As the focus point moved with the camera, it will be where you recomposed. The actual point focused on should still be where you set it it, but the camera has no mark in that place to light up.

BeckyMax wrote in post #9753835
I read that AI Servo doesn't let you recompose with half press. Anyone know?

That's correct. AI servo is constantly refocusing, so if you move the point over something else, it will focus on that instead. You can only lock focus and recompose in one shot mode.

Got it, thanks. Actually makes perfect sense that the camera couldn't know where I was thinking about recomposing. But if I tried BBF, then I would go into AI Servo, correct? Altho unless I was shooting small children, and I'm usually in the studio for portraits, I don't really see any need for tracking.

JimmyNeutron wrote in post #9738075
Well Michelle, FWIW I have the same frustrations. Although I'm often pushing the wide aperture, which exacerbates the issue. An experienced shooter I know is giving up Canon and going to the dark side because Nikon's AF capability is apparently much better.

Have you tried testing your lenses for front focus/back focus? You might want to check out www.focustestchart.com. It's a pretty simple test and you can benchmark all your lenses in a half hour or less.

Your photos are great, by the way. Holy cow, those Barnsons are productive.

Does the focus test work for Canon?

Michelle Brooks Photography wrote in post #9914122
Does the focus test work for Canon?

Do you mean just because it's a Nikon site?

JimmyNeutron wrote in post #9914518
Do you mean just because it's a Nikon site?

Ok it was apparently a dumb question but, yeah, I don't know if there's a diff between testing a Nikon lens & a Canon.....run, Forest!

Are you shooting RAW?

Raw is soft by nature and needs some sharpening in PP.

Also 6.3 would be a little slow for a single subject, which may cause some blur. Try shooting wide open or 1 or 2 stops down. You can also up your ISO.

Canonymous-you meant that when you shoot JPEG the processor applies some level of sharpening before you see your picture whereas with RAW no sharpening is applied.