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<blockquote data-quote="Fred Kingston_RIP" data-source="post: 121727" data-attributes="member: 10742">I bought a SpyderLensCal to calibrate my lenses... there are YouTube videos that suggest less expensive targets... I was shocked at the amount of fine tune I had to apply to some of my lenses to get &quot;sharp&quot;...Most of my lenses back-focus (without adjustments)... My 35mm F1.8G needed a -13 to get &quot;sharp&quot;... and my 18-105mm needs -10Using test shots is sort of hit and miss... because you can't tell which way the lens is going and by how much... You need a good black/white high contrast target to focus... and you need a ruler zero'd out at the black/white focus point set at 45º... The target gets a solid focus, and the values on the ruler (in front of, and behind the zero point) show which way the lens is focusing and relatively by how much... Then you can adjust the fine tune until values on the ruler are equally in/out of focus...</blockquote>

[QUOTE="Fred Kingston_RIP, post: 121727, member: 10742"] I bought a SpyderLensCal to calibrate my lenses... there are YouTube videos that suggest less expensive targets... I was shocked at the amount of fine tune I had to apply to some of my lenses to get "sharp"... Most of my lenses back-focus (without adjustments)... My 35mm F1.8G needed a -13 to get "sharp"... and my 18-105mm needs -10 Using test shots is sort of hit and miss... because you can't tell which way the lens is going and by how much... You need a good black/white high contrast target to focus... and you need a ruler zero'd out at the black/white focus point set at 45º... The target gets a solid focus, and the values on the ruler (in front of, and behind the zero point) show which way the lens is focusing and relatively by how much... Then you can adjust the fine tune until values on the ruler are equally in/out of focus... [/QUOTE]

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