What's the best aperture to use with my Canon 18-200mm lens and 50D?

Question

I am using 50D comes with 18-200mm lens. I wonder what will be the best aperture to use; I mean whatever range (focal length) I am shooting?

Answer

Depends on available light and how much DOF you want. But as an overall recommendation you can use f/8.0 to f/11.0. Aperture faster than f/8.0 produces soft corners and also aperture beyond f/11.0 start to produce soft images due to diffraction.

I guess you're shooting in Aperture Proirity (Av) mode, try getting used to other modes like Shutter Priority (Tv) and Manual (M) as well.

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