Thread: MTF is unimportant; I still want to understand it

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  1. #1 MTF is unimportant; I still want to understand it 
    I know that MTF is a highly technical metric that does not easily translate to day-to-day usage, but I still want to understand how to calculate MTF50. I've ready the Zeiss explainer and Norm Koren websites (personal and Imatest).

    What I'm not sure about is whether to measure min and max values using gamma-corrected numbers or linear? Seems that linear makes my lenses really high MTF whereas gamma makes them look pretty marginal. Which may also be why MTF numbers are just a tech reference and not so meaningful in more subjective evaluations.

    Still, I'm curious.
    Michael Tiemann, Chapel Hill NC

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  2. #2  
    Senior Member Blair S. Paulsen's Avatar
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    Same boat as Micheal, I understand MTF to a point, but would love to know more.

    Cheers - #19
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  4. #4  
    The Lensrentals blog postlings lead to a What is an MTF pdf, which says that Image Intensity should be based on light reflectance in linear space. When I shoot a chart and convert it to linear space, the non-white parts get very dark, which creates the appearance that the MTF is high, flattering my lenses. When I look at chart shots in gamma space, the dark parts of the chart are much more lifted, creating an unflattering appearance of a lousy MTF. I guess I'll take the good news of the linear light space?
    Michael Tiemann, Chapel Hill NC

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  5. #5  
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    https://www.edmundoptics.com/knowled...sfer-function/

    I used to spend hours wandering around the retail store for Edmund Scientific as a kid, they had a periscope in the store, and you could touch any number of prisms, lenses, and optical wizardry. It probably contributed greatly to my interest in optical science to this day.

    Oh, and MTF is quite important, maybe the most important thing to understand about optical fidelity.
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  6. #6  
    Senior Member Blair S. Paulsen's Avatar
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    Quote Originally Posted by Jon Dishler View Post
    (snip) I used to spend hours wandering around the retail store for Edmund Scientific as a kid, they had a periscope in the store, and you could touch any number of prisms, lenses, and optical wizardry. It probably contributed greatly to my interest in optical science to this day. (snip)
    I spend hours with the Edmunds catalogs, would be sweet to actually interact with the optics. Kind of like putting down the magazine and going to the mansion in person. RIP Hef.

    Cheers - #19
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