20D Bad Back Focus - During a Shoot - Any Fix

[taygull]

So I was shooting...uh going to shoot a pretty big act tonight. I noticed 3/4 of the way through shooting the first band my focus seems a touch off. I thought maybe it was just me.

So while the crew was doing the tear down and setup I started trying to AF...and guess what NO CHANCE. I tried everything, switched glass, took the batteries out for awhile and nope. I'm not talking about a slight OOF I'm talking about complete blur no chance of saving the shots.

All of a sudden it is back focusing, in order to get the subject in focus I'd have to focus at least a foot or two in front of it.

I'm wondering how this all of sudden starts to happen and is there a reset of some sort that might fix this. If not I guess I'll have to send it to Cannon.

[taygull]

I'm suprised that there has not been anyone else with this problem?

[adas]

Have you tried with another lens?
Although there isn't a particular focus reset, you could remove the main battery and the long-term button cell for about 5 min. That will reset pretty much everything.

[taygull]

Now what is crazy is the dang thing is front focusing this morning.

Yes I tried all lenses, I did remove the main batteries and the long term battery last night. Maybe that is why it is front focusing today instead of back focusing....

Very crazy. It is not as bad today but it is very clear that it is front focusing when I shoot text and look at it in the EOS viewer utility and add the AF points to the view.

I'll post a couple of shots in a bit.

It may be close enough I can get the two shoots I have this week and then send it in for calibration.

[taygull]

Here are some shots...

I'm not sure what the heck is going on...

If I look at a comparitive shot from last night it looks like it was front focusing very bad not back focusing......Here you will see two shots 100 frames apart. Unfortunatly I can not determine the exact point because I moved back stage and did not adjust a setting so even though there was a series of about 50 frames that are OOF is could be due to a slow shutter speed.

The pics below are at f/2.8 and at least 1/250 with the 24-70mm @ ISO 1600.

You can see in the first shot it is pretty sharp, these are 100% crops.

I was using center focus point and I picked shots where I did not recompose after focus. The focus points are on the face.

http://i100.photobucket.com/albums/m16/taygull/testIMG_8544-01.jpg

In this shot the focus point was on the nose. In the full size image there is a mic stand that was about 4' closer to me and it was close to be in focus, this is telling me it was front focusing.
http://i100.photobucket.com/albums/m16/taygull/testIMG_8644-01.jpg

Here is a shot from this morning, 100% crop. F/5.6 1/800 ISO 100

http://i100.photobucket.com/albums/m16/taygull/100_crop.jpg

[taygull]

My latest test after I removed all batteries, even the permanent one.

It seemed to work OK for a couple of shots and then all of a sudden it was back to OOF shots. It seems worse the further I am from the subject.

Looks like it is off to Canon.

[adas]

Sounds like the focus unit got loose or something. It might be time for Canon to look at it.
But in the mean time, try cleaning the contacts in the camera mount and lens, maybe the camera's having a hard time communicating with the lens?

[taygull]

Sounds like the focus unit got loose or something. It might be time for Canon to look at it.
But in the mean time, try cleaning the contacts in the camera mount and lens, maybe the camera's having a hard time communicating with the lens?

I'll try that but I don't think that is the problem. The camera focuses fast as it always has, it just focuses wrong.....

It is now 100% a back focus issue, when I shot some leaves on a a bush the leaf the AF point was OOF but the leaves behind it were in focus.

I've got a very important shoot Tuesday so I'll have to go manual and then send it off. I'm guess I'll send the glass as well so they can calibrate it.

The body is out of warranty but the 24-70 and the 70-200 are in warranty.