Lens Calibration? DAMN IT!

[savona]

I did a fun shoot with a friend of mine today. After downloading all the photos I noticed the focus was missed on a lot of them when shot at 2.8. The problem is I know for a fact that I didnt miss all these shots. I mean sometimes my head gets out of the game and I miss, im human. But out of nearly 100 shots all shot at 2.8 are back focused. I think I need a calibration on my lens??? I just had the lens and camera calibrated at a canon service center here in NJ about 8 months ago. Is this normal to need it so often?? Or is there something I can do to make the calibration last longer? Or is this another case of user error?? I noticed on this particular shot I could have put the AF point on here eye (which I should have done) and maybe the more contrasty (is that a word?) area of her eye would have proved to be a better focus point? Any ideas??


As you can see it is back focused almost a good 4 feet or so, this is odd...

[LuisV]

There's a great deal more to it than that. It depends on the setup of the camera's AF and other factors. I am not familiar enough with Canon's system, but I would gather that the camera selected an area with better contrast to focus on. For example, in this case, the place where the window blinds meet the wall.

It's more than likely settings related.

[Hikariphoto]

This problem is twofold here. First, you're using a 24-70 2.8 lens. This lens is known to be a problem child for Canon. I know people who have returned or repaired theirs multiple times and still they get backfocusing (which really isn't backfocusing, BTW. Backfocusing is where the focus point of the lens is behind the film plane, resulting in an image that is entirely out of focus.). In this case, look at your active focus point. It's on an area of her face that has absolutely no contrast, so the camera (not the lens) told the lens to focus on anything that has contrast, and you ended up with the blinds in focus and her out. I'd say get rid of the lens and get a 24-105. Now that's a beautiful lens.

There are a couple of ways to deal with this. You can put a 580EX on your camera and use the flash's focusing beam to lock focus, and set your custom function 07 in the camera to "does not fire" -- the camera will use the focusing beam but not fire the flash, leaving you free to use studio lights. Another way would be to use the peripheral focus points to grab something with more contrast. You could also pick up an ST-E2 transmitter (not cheap) because it emits the beam but doesn't have a flash to fire.