Relation between MTF and Magnification

  • 6 December 2022
  • 2 replies


Hello all,

According MTF definition, MTF describes the contrast in the image of a spatial frequency. Therefore, this is no magnification information in MTF graph directly, correct? In another word, if the value of MTF at 100c/mm is large than 20%, it doesn’t mean you can see object with 10 um resolution if the magnification is too small, right?

For example, the first MTF can’t see the USAF 1951 target 5.5 (50.8 l/mm) even MTF have real good performance. The second system with second MTF can see the USAF 1951 target 5.5 even MTF has bad performance compare to the first MTF. That’s why I think MTF doesn’t really show magnification information directly. Please correct me if I am wrong. Any thoughts are appreciated.

lens system with small magnification
lens system with large magnification




Best answer by Andrey.Pravdivtsev 12 December 2022, 10:08

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Userlevel 3

You need to scale object frequency to image side frequency based on your magnification to understand what object you can see. MTF shows only optical system performance.

Userlevel 1

可能把 像面MTF和物面MTF混在一起考虑了