## ilza's recent activity

• The only way to refute or support “your expectations” is to (1) Stop trying to bully me (won’t work anyway!); (2) Analyse the geometry, estimate the ...
• How one should be able to see this? Remember that for the central sensor, I predict that there is no difference. For far-from-center sensors on not-mid-telecentric lenses: (1) the external (circular) ...
• I have no clue.  All I know that a lot of people discuss telecentricity in meaningless terms (so many that they swamp the whole ecosystem; therefore, I do not know any reasonable discussion), AND ...
• Replied in Whoosh!
Of course one CAN. This is the whole idea of geometric optic of (approximately) aberration-free systems. Optical elements may be freely moved between different “spaces” (corresponding to real — or ...
• For the people who love to put quotes about the word FUNDAMENTAL, it may be useful to go and see how the graph of sine looks like.  While google’s calculator cannot do sin(120°), google itself ...
• Thanks for the correction! ??? What is the difference? To calculate f/D, one must know f. (D is the easy part.)  And different zones of the lens would have different f. But the whole topic of this ...
• Hmm, this means you do not know the definition of f for an optical system. f = distance_on_focal_plane/angular_unit Take images of two stars separated by 0.001°.  If their images are separated by ...
• First of all, I cannot parse “taking the convolution frequency domain response to zero”. Second, I never tried to think in terms of “visual ugliness of noise”.  Moreover, I do not think it is ...
• Jim, first, my apologies for the delay: I’m still pulling myself from under the rumble… I hope to somehow manage better in a week! Second, the “divergence” in my graphs is not between the 3 curves ...
• … The moment you have a significant coma, any discussion of f AS A NUMBER ceases to make sense: COMA means that different paths through your optical system have different magnification — hence ...
• The sensor IS the imaging medium. No, the Abbe’s theorem does not say anything about what happens IN BETWEEN. You are right that it ALSO does not say that the limit is REACHABLE — but I did not say ...
• I repeat: there cannot be image-forming system with D/f > 2.  Try this: take a long exposure, and during the expose, gradually change your zoom 2x.  The image would show what a 2x-coma looks ...
• Again, there is NO TRUNCATION in this context. Just proportions. Since we KNOW that 0xFF corresponds to 0.FFFFFFF…, we KNOW that 0xE3 MUST represent .E3E3E3E3…. There is no “assumption” in our ...
• One addition/correction: above, “some other point” means “some other point INSIDE THE SAME GROUP”.  (This is due to different groups using different separation windows in the separation mask.) Hmm, ...
• Thinking about this more, what this shows is that Marianne’s analysis is 100% correct in ONE MORE case: in addition to the mid-telecentric lenses, it is also applicable to the center focus point. ...
• Judging by your puzzlement, you are not miopic. I am — and your image MATCHES EXACTLY how I would SEE back-lighted things when I’m not in my for-far eyeglasses. Ilya
• Depends on what problem you are solving. In your opinion, the 8-bit value 0x01 represents which brightness (on the floating-point scale from 0 to 1)?  If you think it is 1/256, think again. One ...
• As I said, the only aspect of telecentricity important in this context is the position of the plane of the exit pupil (in other words, of the “virtual diaphragm” — the diaphragm mapped to the ...
• Then we read what Marianne wrote in completely different ways. How I read it: analyse how the AF system works — up to the point that one can PREDICT its behaviour in different situations. To the ...
• The limit is a fundamental mathematical phenomenon. It does not depend on the design of the optical system at all. If you want to GET AN IMAGE, you need to satisfy the Abbe’s law, so the NA < ...
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