mark_goldsmith1 Posted December 15, 2006 Share Posted December 15, 2006 I hope I can ask this question right. Does a MTF figure of 2113 (for nikkor 28-70/2.8 taken at 28mm) necessarily sharper than a figure of 2028 (for a nikkor 17-55/2.8 taken at 24mm), both at the center. Please note that the spirit of this question is not to compare the lenses, I just want to know how much we can rely on this measurements. Thanks Link to comment Share on other sites More sharing options...
tommyinca Posted December 15, 2006 Share Posted December 15, 2006 You may be referring to other types of resolution measurement system. MTF results are normally listed as a floating point number between 1 to 0 associated with a line pairs per milmeter (e.g.: 40lp/mm) parameters. In chart form, the x-axis is typically distant to the center of lens. Link to comment Share on other sites More sharing options...
alex_lofquist Posted December 15, 2006 Share Posted December 15, 2006 MTF also means Mean Time to Failure. Link to comment Share on other sites More sharing options...
andy a. Posted December 15, 2006 Share Posted December 15, 2006 I'm guessing those numbers are line pairs per picture height, and the two are very close to each other, maybe even within the standard of error for that type of test. Link to comment Share on other sites More sharing options...
yeux tortu Posted December 15, 2006 Share Posted December 15, 2006 Yes, it is sharper, the measurement is independent of focal length. Link to comment Share on other sites More sharing options...
yeux tortu Posted December 15, 2006 Share Posted December 15, 2006 Read Mr Atkins article; http://www.bobatkins.com/photography/technical/mtf/mtf1.html Link to comment Share on other sites More sharing options...
yeux tortu Posted December 15, 2006 Share Posted December 15, 2006 Looks like photozone MTF ratings. I think they do a good job but they test a limited amount of samples. Directionally the results are right, but degree of difference is probably not as precise as the numbers would seem to indicate. Their quantitative rating of the Nikkor 85 1.4 and 70-200 2.8 is probably inconsistent with my field impressions (I think they are sharper than measured). But perhaps the mythical status of these lenses clouds my perception of results.Or maybe I have better samples than the loaners which they tested. Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now