Canon 50mm f/1.4 focus and sharpen problem

Plane of focus in both pics appears to me to be the pink ball in front.  The green ball is out of focus in the first because it is beyond the shallow depth of field at f/1.4, but is sharper in the second because it is well within the depth of field at f/8.

The lens (and/or the camera) may be front-focussing a bit and need calibration if it was actually autofocussing on the green ball.

Or ...

Did you select the single center focus point to be active?   The individual sensors are a bit larger than the boxex in the viewfinder and may have covered the pink ball.  If you used the default setting of Auto Focus Point Selection, that will AF on the closest subject covered by any of the sensors.

kusser wrote:

Hi. I'm new at the forum, so please forgive me if I'm asking something you already answer. I have searched around the forum (and all Internet!) and, although I found similar cases, I didn't found an answer.

The problem is: I'm unable to get sharp images with my 50mm lens on high apertures. For example, if I try at f/1.4, with 1/500 and 10 feet from the subject, I only get blurry images of my subject and I get focus on other points of the image.

I have made some tests with a tripod and different distances, with no better result.

I will show you two examples (I have a lot). The first one is at f/1.4 with 1/500 and 10 feet from the subject (the green ball). You can see that I don't get a sharp image.

The green ball is the subject and where my focus point is.

The second one is with the same conditions, but f/8.0 with 1/80. And here I get good result.

The green ball is now sharp.

Both were taken at the same moment, with a tripod.

My camera is a Canon T3i.

If you can help me, will be great.

Thanks a lot in advanced.