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MTF comparison for AF-S 50mm F1.8 and AF-S 35mm f1.8
Hi everyone,

I am looking at below pages and I want to conclude which lens is sharper.




can I compare those MTF graphs (considering that they tests have been done using different bodies with different pixel density)? Are those graphs consistent?

If the graphs are consistent then I can conclude that 50mm F1.8G is much more sharper everywhere?


[quote name='wmac' timestamp='1312108166' post='10331']

can I compare those MTF graphs (considering that they tests have been done using different bodies with different pixel density)?



If you would compare the results from different cameras (different megapixels) but the same sensorsize,

you would see that the actual numbers on the charts differ (due to the different megapixels) but that

the tendecy of the graph is the same (and comparable).

But you compare the results from cameras with different sensorsizes ... this comparison is absoluely


Just my 2cts ... Rainer
The MTF numbers can only be compared directly between tests made with the same camera. The LW/PH scaling includes the maximum picture height in pixels, so a camera with a much higher resolution sensor will (usually) achieve much higher maximum LW/PH numbers.

However, the rating that we put next to the graphs can give you a rough guidance to compare lenses tested on different cameras. However, please note that some lenses can behave differently on different sensor (well, it's the sensor that behaves differently, of course) and the sensor size should be roughly the same.

The two tests you're mentioning here are done with two very different sensor sizes. That means that the border and corner measurement spots are a good deal further away from the image center in the FX test, in absolute terms. The relative position of course is the same.

-- Markus

Reiner, Thank you very much for your comment.

Markus, thank you very much for the time you put to clarify. It is very much appreciated.
Besides the difference in sensor sizes for the tests (one being APS-C and the other full frame), I am sort of wondering why you want to compare the sharpness of those two lenses?

The focal length, and therefore the field of view, is quite different... So much different that that is way more important a difference than which lens is sharpest...

Both lenses anyway are sufficiently sharp. The 50mm f1.8 is alround a good lens, I am a little bit less impressed by the 35mm one in terms of bokeh smoothness and CA performance.

Determine which focal length is most valuable for you (the 50mm being more a short almost portrait lens on APS-C, the 35mm more a normal shoot-everything lens), and base your choice on that.

Slight differences in sharpness are not noticeable in photos, but the big difference in field of view is very apparent.
I guess the intention was to find out which lens produces sharper images, the AF-S 50 on FX or the AF-S 35 on DX.

There's more to it than just the lens, though. And there's more to a lens than just sharpness.

-- Markus


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