50 mm 1.4 USM canon lens

By: romenshah 5601 days ago
I am rather new to the 50 mm 1.4 canon lens on my " not so new " canon 350D camera.

Not quite satisfied with the results, because it tends to autofocus on the nearest object and create an out of focus image for the objet just behind.

Example is a picture of a boy with extended arms, wherein the auto focus selects the hands and the face of the boy is burred.

This happens even if the image is shot at f2.

The same shot focuses the entire picture very clearly with a 18-55 lens.

Any guidance as to how to deal with such situatins.
By: johnriley 5601 days ago
It's all a matter of depth of field. DOF is the distance between the nearest and furthest points that are sgarp in a picture.

There is very little DOF at wide (large) apertures such as f1.4 and f2. There is maximum DOF at the smallest apertures such as F16, f22, f32, etc. And of course a gradual increase in DOF as we go through the middle apertures.

So you basically need to use a smaller aperture to get more in focus. Your 18-55mm lens has a smaller maxium aperture of probably only f3.5, and maybe f5.6 at the telephoto end, so you will have been using it at smaller apertures and getting more DOF.

The other factor is the point of focus and it is generally better to select the "centre spot only" as the focusing point. Focus on the place you want sharpest and then hold and recompose.

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