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.
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.
Thanks. What is the size of the test chart?
The std chart is currently 130x90cm (see Lens Test FAQ for details).
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.
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.