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At what distance are the Imatest charts tested? - Printable Version

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At what distance are the Imatest charts tested? - Canuck - 11-05-2015

At what distance are the Imatest charts tested for various focal lengths? I am particularly interested in prime lenses for the wide angle, normal, and short telephoto ranges (35mm equivalent). Thanks for a great and very informative site.


At what distance are the Imatest charts tested? - Klaus - 11-05-2015

The object magnification is what counts - the focus distance derives from there.

 

Generally we are using:

- Full format: 1:34

- APS-C: 1:52

- Four-Thirds: 1:63

 

As an exception to the rule, we are sometimes using less or more depending on the lens type.

 

Out of curiosity I once tested an full format ultra-wide lens at 1:80 but that didn't really make a substantial difference. Vice versa, a test at 1:10 had a much high impact but then print quality is certainly also a limiting factor.




At what distance are the Imatest charts tested? - Canuck - 11-06-2015

Thanks. What is the size of the test chart?


At what distance are the Imatest charts tested? - Klaus - 11-06-2015

The std chart is currently 130x90cm (see Lens Test FAQ for details).




At what distance are the Imatest charts tested? - joachim - 11-06-2015

Quote:The std chart is currently 130x90cm (see Lens Test FAQ for details).
If my algebra is correct, that is about 2m for a standard lens.



At what distance are the Imatest charts tested? - Canuck - 11-06-2015

This subject is new to me so forgive me if I am incorrect in saying that I calculated 1.65 meters for a 50mm lens on a full-frame body.


At what distance are the Imatest charts tested? - Klaus - 11-07-2015

Quote:If my algebra is correct, that is about 2m for a standard lens.
 

That is correct.

 

http://www.giangrandi.ch/optics/focalcalc/focalcalc.shtml

 

Just enter 900mm (Object size), 24mm (image height), 1.93m (distance) into the form.