Just bought a used 5d Mk II off these forums.

It has 2 problems. It won't focus with the 1/2 shutter push except in [ ] (green, full auto) mode. In all other modes, it ignores the 1/2 shutter press. It's not a matter of lens or lighting because if I press the AF button it will instantaneously auto-focus and it happens on more than one lens.

I've tried resetting to factory to factory defaults with no change in behavior. Firmware rev is 2.07.

The other issue is that it's consistently underexposing by a stop when I use it with my 580EX flash. If I move the flash over to my rebel Xsi the exposure is perfect.

Please tell me this is user error of some type. Otherwise, I'm pretty distraught!

Is your custom function set for back button focus? probably is...

check your manual (I don't have one handy). If the "AF ON" button works for focusing in other modes, that's likely the problem.

edit:

here it is:
Custom Function Group IV – Operation/Others settings

C.Fn IV -1 – Shutter button/AF-ON button

This is one of the most used Custom Functions as it allows you to set back button focus, so you can shoot static and moving subjects without having to change the AF mode.

Setting 0 – by default the Shutter button and AF-ON button both activate metering and start AF functions.
Setting 1 – causes the shutter button to start metering and AF operation, while the AF-ON button acts as an AF Stop to pause AF operation.
Setting 2 – this is one of the most common choices. The shutter button will start exposure metering and the AF-ON button will start autofocus and metering.
Setting 3 – this is another common one, with the shutter button being used to activate AE lock and the AF-ON button starting metering and autofocus.
Setting 4 – this disables the AF-ON button and makes the shutter button start both metering and autofocus.

make sure C.Fn IV -1 is set to 0 if you want 1/2 shutter button press to start auto focus

I know you mentioned you reset factory defaults, but the focusing issue seems like C.Fn 4-1 is set to something other than 0.

Rob Whiting wrote:
Is your custom function set for back button focus? probably is...

check your manual (I don't have one handy). If the "AF ON" button works for focusing in other modes, that's likely the problem.

wouldn't that get cleared when I reset to factory defaults?

jzucker wrote:

wouldn't that get cleared when I reset to factory defaults?

I would think so.. you'll have to check.. is C.Fn IV -1 set to 0?

I just cleared custom functions and it started working again in all modes with the 1/2 press. Shouldn't the factory settings reset clear that?

jzucker wrote:
I just cleared custom functions and it started working again in all modes with the 1/2 press. Shouldn't the factory settings reset clear that?



page 45 of the manual tells you what "clear all camera settings" clears.. The very last thing on that page: "custom functions - no changes"

just did a test. Resetting to factory defaults does not clear custom functions!

What about the underexposure thing with the 580ex?

sorry, I don't have a manual with it though the PDF would actually be better. Guess I need to download it from canon.

thanks.

jzucker wrote:
just did a test. Resetting to factory defaults does not clear custom functions!

What about the underexposure thing with the 580ex?


Did you test before you cleared all camera settings & again after? You may have had FEC set. Clearing camera settings would reset that back to 0

yes, I just tried the flash again and it now seems to be exposing properly.

Thanks folks. Sorry for the newb questions.

Update your 5D2 with 2.1.1 F/W

mttran wrote:
Update your 5D2 with 2.1.1 F/W

Thanks. Will do after the charger arrives.