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lens testing info?

S

Steve

Guest
Hi guys, I posted this in the canon forum but thought I would post it here also seems like a little more traffic here. What is the proper method for checking accuracy of lenses. I've heard to use a ruler at an angle. What distance is appropriate? Any info would be helpful. I am checking for front or back focus issues. Thanks Steve
 
S

Steve

Guest
I should probably posted this in only one forum. Thanks for the help I will check it out. Steve
 

Jack

Sr. Administrator
Staff member
Hi Steve:

I use to use fancy targets and rulers with tape on them, but now I simply shoot at lines in the sidewalk, focusing where two intersect at the distance I normally use the lens at, usually around 40x the lens focal length. With this method, it's really easy to see where your exact focus point was relative to where it should be... The 40x focal thing moves that point toward the usually more critical closer focusing distances where DoF will not always rescue slight mis-focuses.

Cheers,
 
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Steve

Guest
thanks Jack, I was wondering shooting some of the ruler tests at such a close distance how you could measure how far out you are at say 10 feet or so.
40x sounds like good advice. I'll give it a go.
 
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