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| Measuring lenses objectively – Part 2 |
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In the first part of this article - published in issue 30 of the Camera
Lens News - Dr. Hubert Nasse, Senior Scientist of the Carl Zeiss AG, gave an answer to the question “Why do we need MTF curves?”
We have already seen how the shape of the point images as determined by the aberrations and diffraction on the one hand correlates with the modulation transfer on the other. We also encountered the various graphical depictions of the MTF, and I showed you four different basic types of transfer functions in the chapter on contour sharpness and image contrast.
Basically, we have learned the basics of how to read MTF curves, but all this is a bit theoretical considering that images are what really matters. In this article, we will therefore be examining MTF curves within the actual image.
To do this, we will look at different motifs each of which were
imaged using twelve different transfer functions. Obviously, these images must be available at sufficiently high resolution, so instead of including them in this text they are available for you to download from our server. The PDF includes the MTF curves relating to the images as well as additional explanations.
Please read on here in order to disclose more secrets around MTF curves.
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March 2009 |
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