Back-focusing, camera or lens?

Started Sep 23, 2012 | Discussions thread
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PrebenR Veteran Member • Posts: 3,529
Back-focusing, camera or lens?


With my SD15 I have noticed that there seem to be some back focusing. One of my lenses a 50mm f1.4 has already been tested and found ok, but I feel that on my SD15 it isn't.

Today we had a lovely morning, cold, blueish colours and in the horizon very nice cloud formation in the sunlight. Our house is in the shadow of a mountain in the morning.

I wanted to get a photo of the nice horizon, but all my shots at 200mm where severely out of focus. Didn't matter where I focused on the horizon. Not I didn't focus on the clouds themselves. So I then did a photo (see below) where I focused on the closer chimney, but if you see the original sized photo, the roof and chimney furhter away is in focus. So it seems the problem is back focusing. I have also suspected this from other lenses I have, so I'm wondering if it is the camera that needs to be adjusted. Any hints much appreciated.

When I tried to manually focus (actually I did that yesterday) and I seem to nail the focus better.

My question is is it the camera or the lens(es) which is the problem?

Test photo with AF. Focusing on the nearest chimney. Actual focus is on the one behind if you see the original in the link

Original :

Manual focus

100% crop:

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AF takes away the Zen in photography

Sigma SD15
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