05-15-2011, 05:20 PM
Because of a recent problem with one of my lenses, I have been analyzing (probably over analyzing) the sharpness of my lenses. The one lens I have sent in for service definitely had a focus issue....probably due to it bouncing off of the concrete after falling from my camera bag when I tripped <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/rolleyes.gif' class='bbc_emoticon' alt='
' />. I am satisfied with two of my other lenses' performance, but my Sigma 15-30mm has gotten my attention. I very rarely use this lens as I have never been really happy with it's sharpness.
How can I easily determine what level of sharpness is acceptable for this lens and when it should be sent in for adjustment? I use it on a Canon 40D and the images do not look sharp at all away from the center. Is there a reliable at home test? I want to either verify that the lens is overly soft or that I am overly paranoid! <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/tongue.gif' class='bbc_emoticon' alt='
' />
' />. I am satisfied with two of my other lenses' performance, but my Sigma 15-30mm has gotten my attention. I very rarely use this lens as I have never been really happy with it's sharpness. How can I easily determine what level of sharpness is acceptable for this lens and when it should be sent in for adjustment? I use it on a Canon 40D and the images do not look sharp at all away from the center. Is there a reliable at home test? I want to either verify that the lens is overly soft or that I am overly paranoid! <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/tongue.gif' class='bbc_emoticon' alt='
' />