k-hawinkler
Well-known member
I did. Clearly, both are better, for color transparency, contrast, corner sharpness and, obviously they are 2,8. In particular, as you know having it, the 28 from full open eoutresolves
the
sensor of the a7r on a large part of the image,and, at F8, generates moirè till extreme corners.(probably the sharpest 28 ever built)
But... quality advantage is less than one could think. The 16-35 considering also all other
advantages, is very near. As you do, I am also wandering..
Sergio
Is that a correct statement?
I thought a better lens gives a better image on a given sensor.
And vice versa a better sensor gives a better image with a given lens.
So it's the combination that counts.
Therefore my question. TIA.
Many, many thanks Sergio. Please could you show how you proceed.K-H, the reply to your question, to avoid to be generic, is neither simple nor short, and requires to cite Nyqvist's theorem, spatial frequency etc.
In practice, let's put the thing this way, if you agree.
A sensor has a resolution that is strictly related the number of pixels in a
defined surface, (pixel density). That resolution can be measured in Line pairs per mm, and in the case of a7r this value is approx. 100 for vertical and horizontal lines. (a little less for oblique)
If the lens has a resolution greater than 100, the part exceeding 100 cannot be
correctly recorded by the sensor, and creates aliasing, better known by photographer as moirè. everytime you see aliasing on a digital image, you know that the lens has more resolution than the sensor. When the sensor reaches its limit, it can no more cooperate with the lens to produce a better image.
I do this measurement with every new lens I get.
If you want, (I esitate to show resolution targets in this forum :sleep006
I can show how I proceed.
Sergio
If you don't want to show resolution targets in this forum could you please post them on dropbox and post the url here so that I can have a look at them. TIA.
So please let me ask you, if I understood your explanation on examples, if I may.
Let's assume a sensor can resolve 100 line pairs per mm (lppm).
Let's also assume the first lens can resolve 100 lppm.
Now if one uses another lens with 200 lppm on that sensor with 100 lppm resolution one doesn't get a better image.
Is that correct?
However, in case of the A7R, if one starts with a lens that resolves less than 100 lppm and then changes to a lens that resolves more lppm that would resolve in a technically better image.
Correct?
I also would appreciate if you could comment on this thread
MTF Curves ~ Sensor Resolution - Leica User Forum
and in particular this post, quote:
"Quote:
Originally Posted by k-hawinkler View Post
I am interested in quantitatively comparing the resolution of Leica lenses with the resolution of digital sensors. So, I would like to know how one can determine whether a given lens outresolves a given sensor and vice versa ...
01af: I wrote so many articles in this topic here in the recent two years ... obviously it was entirely futile.
So let me repeat it once again: Lenses don't outresolve sensors, and sensors don't outresolve lenses. Better lenses are better on any sensor and better sensors are better behind any lens.
Quote:
Originally Posted by k-hawinkler View Post
... or whether the resolution of lens and sensor are comparable.
01af: No, they are not.
Quote:
Originally Posted by k-hawinkler View Post
Do Sensors “Outresolve” Lenses? by Rubén Osuna and Efraín García on Luminous Landscape.
01af: This useless article is full of layman's errors and misconceptions. The maximum useful sensor resolution is not a matter of absolute limits but of return on investment. How much are you willing to spend for further (small) improvement if your current system already is very good?"
Thanks again for your help.