T1i AutoFocus Question: Viewfinder vs. Liveview

Ok so I've been trying to narrow down why some pictures can come out soft on my camera and others are crisp and whether or not it is user error, the camera or both.

Here are some samples of my trials with my T1i and Nifty Fifty.

All photos are tripod mounted, two second timer on camera, and used the built in flash. Focus point is the second piece from the left of the guitar's bridge, manual focus point, set to middle, AI Focus.

Narrower stops produced better results so I'm wondering if this is inherent of the nifty fifty being wide open vs. say f5.6+. Regardless I found it interesting that the camera doesn't focus as well using just the view finder vs. live view and zooming in on the same focus point.

Nifty Fifty
f1.8 1/60 ISO400 View Finder Focus

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Oh, and these are 100% crops

Focusing is incorrect.

It could be that the AF point you are using is picking up something else than you think. We need to see the whole image to have any clue about if that's possible.
Then it could be the lens and/or camera that requires calibration.

I have an EF 50 mm f/1.4 USM that's literally worthless on those of my cameras that lack microadjust. Had I not mainly used it on the 7D, then I would have been forced to send it back for calibration. The microadjust frequently just changes the characteristics of the problem, but in this case, it does actually handle this issue well, so I let it stay with that.
But the 500D does not support such adjustments, so the only thing you can do is to request calibration at a service center.

instead of AI focus, try one shot focus and see it the situation has improved.

live view AF (contrast based) will almost always be sharper than regular view finder focusing especially with nifty fifty... my 50 1.8 is definitely a hit or miss AF thru view finder but awesome thru live view especially at f/2.5 where its tack sharp

onick wrote in post #12374425
instead of AI focus, try one shot focus and see it the situation has improved.

AI Focus uses One Shot AF to begin with, and doesn't change from that unless the subject distinctively moves, which does not seem to be the case here, so I can't see that there's any difference in the method at all.

same first picture

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Where was the AF point?

I'll have to get it out of Lightroom tonight, I'm guessing you need more specifics than "Focus point is the second piece from the left of the guitar's bridge, manual focus point, set to middle, AI Focus.
"

My nifty-fifty is soft on my 500D at 1.8 but at f4 it is very sharp.
For pictures like yours I would't use tripod.
I'll switch to live view on MF, select x10, prefocus with lens ring and fine tune with my body.

AF point added to larger picture

To mix this up some more, here's the "battery" test, here it came out perfect... Middle battery is the focus point

F1.8 1/10 ISO100

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I am going to side with my countryman here, it's either a back/front focusing lens or the AF-Point is picking up something else. Did you manual focus the liveview one?

FastGT94 wrote in post #12378520
AF point added to larger picture

OK. There is no problem with your camera. The AF points are effectively larger than their representation in the viewfinder and in the viewing software. The camera have found the string to the left of the AF point to be a nice target, and focused on that.
You need to be aware of this fact, and act accordingly in the situations where it may cause a problem. Like when aiming at a slanted subject, as in the picture of the Fender.

I guess where I get a little confused is that when utilizing auto focus when in live view, zoomed in, the picture became more focused. Is this somewhat of a design intention? Live view zoomed in does take its sweet time focusing when compared to the viewfinder, so my assumption is yes.