Canon 24-105 Calibration needed?

I just picked up a Refurbed 24-105 from Adorama and I am concerned with sharpness at F4. I have read that a lot of people praise this lens for being sharp across the entire range and have also read people complaining about softness at F4. Stopping down to 5.6 makes a lot of difference, so much that I am questioning why F4 isn't as sharp as 5.6.

This this screenshot image from DPP, the left shot is at F4 and the right shot is at 5.6. Would this difference warrant a calibration? Or a return? Really soft on the eyelid at F4. IS was on, handheld at 200, ISO 400 with direct ETTL flash.

I shoot wide open all the time so it is a concern for me. Similar results throughout the focal range. I tested at 24, 50 and 105. I applied -3 MA to it because it was back focusing during testing. On a 5D2 body.

Thanks

http://fixedfocus.us/i​mages/Canon24-105Test.png

the left shot is also focuses on an area with very little contrast, while the shot on the right, the focus point is sitting on an area with a lot of contrast.

va_rider wrote in post #14363624
the left shot is also focuses on an area with very little contrast, while the shot on the right, the focus point is sitting on an area with a lot of contrast.

It had no problem locking on though. If there wasn't enough contrast, wouldn't it hunt until there was? I need to be able to trust the AF. When it says locked, it needs to be sharp.

there are too many variables there... you're shooting a person that moves... maybe you're on a tripod, maybe not... using "One Shot" focus, if the person moves at all from the time you lock focus, to the time the button is all of the way down, you're left with a OOF shot....

If you're really concerned, and really want to check.... put the camera on a tripod. find something with high contrast to shoot at. use 2 sec delay to eliminate shake.

va_rider wrote in post #14363722
there are too many variables there... you're shooting a person that moves... maybe you're on a tripod, maybe not... using "One Shot" focus, if the person moves at all from the time you lock focus, to the time the button is all of the way down, you're left with a OOF shot....

+1

Too many variables. No exif info. Test the lens on tripod and if it's ok then there's no one to blame but yourself.