I want to know whether MTF curve of a lens can be tested.
The sharpness of a lens is a combination of resolution and contrast.
Subjectively a lens with great contrast but rather mediocre resolution looks more snappy, maybe even sharper than a low-contrast lens with a high resolution.
MTF50 is not a measurement for sharpness but a measurement for resolution. It cannot show contrast of a lens.
But MTF curve (not MTF50, they are two different concepts) can show the contrast of a lens. Some lens manufacturers offer MTF curve of their lenses, but some don't.
Can someone tell me whether MTF curve of a lens can be tested?
Le Kuai
You can test conventional MTFs on an optical bench. This is "just" a matter of costs. However, this is purely a lab test - it ignores the interoperability of lens and camera sensor. This is e.g. most obvious when testing symmetrical wide-angle lenses on mirrorless cameras. The real world result is very different from an optical bench. This is not just a mirrorless issue. The real world vignetting is much higher on a DSLR than on the lens alone just to mention an obvious effect.
We looked into providing contrast data in our test. However, the problem is that these results not overly stable so as of now we are feeling uneasy to publish this.
Klaus
[quote name='Le Kuai' timestamp='1331282472' post='16495']
...
Can someone tell me whether MTF curve of a lens can be tested?
Le Kuai
[/quote]
If you have one of these, yes <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/smile.gif' class='bbc_emoticon' alt='
' />...
http://www.zeiss.de/C1257569004B5D2C/Emb...ter_K8.pdf
OTOH, as Klaus already mentioned measuring system results has it pros... but maybe also has some cons...
I've been reading this article yesterday, and I think it's very informative (actually I copied the link above from that article). The content on that site is very rich and informative. And this specific article pulls attenion to various topics, which are not considered in system tests:
http://toothwalker.org/optics/lenstest.html
[quote name='Klaus' timestamp='1331285411' post='16496']
You can test conventional MTFs on an optical bench. This is "just" a matter of costs. However, this is purely a lab test - it ignores the interoperability of lens and camera sensor. This is e.g. most obvious when testing symmetrical wide-angle lenses on mirrorless cameras. The real world result is very different from an optical bench. This is not just a mirrorless issue. The real world vignetting is much higher on a DSLR than on the lens alone just to mention an obvious effect.
We looked into providing contrast data in our test. However, the problem is that these results not overly stable so as of now we are feeling uneasy to publish this.
Klaus
[/quote]
Thanks for your response! <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/smile.gif' class='bbc_emoticon' alt='
' />
[quote name='PuxaVida' timestamp='1331295473' post='16500']
If you have one of these, yes <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/smile.gif' class='bbc_emoticon' alt='
' />...
http://www.zeiss.de/C1257569004B5D2C/Emb...ter_K8.pdf
OTOH, as Klaus already mentioned measuring system results has it pros... but maybe also has some cons...
I've been reading this article yesterday, and I think it's very informative (actually I copied the link above from that article). The content on that site is very rich and informative. And this specific article pulls attenion to various topics, which are not considered in system tests:
http://toothwalker.org/optics/lenstest.html
[/quote]
Thanks for your response! I appreciate the website you provide. <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/smile.gif' class='bbc_emoticon' alt='
' />