[Rollei] Lens charts

["Dan Kalish" <kaliushkin >]

 Where would I find a guide, preferably on-line, to understanding lens
charts?  Alternatively, if
 it could be put in a few words, please explain here?

 I've come across two types of charts:

 MTF: http://www.butzi.net/rodenstock/apo-sironar-n/180mm.htm

 Modulation:
http://www.schneideroptics.com/photography/large_format_lenses/apo-symmar-L/pdf/ApoSymmarL_56_180.pdf

 Thanks,

 Dan the K.

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