Depth of field appears "irrelevant" to you because you don't understand the notion of "Circle of Confusion" used in DoF calculations.
You make me laugh... Seriously. I perfectly understand circle of confusion and depth of field calculation. They are irrelevant here because you will never EVER see any modification of DoF because of ray inclination.
The intersection of the lens' light cone and the image plane is a disc. The light rays near the periphery of the cone are more tilted than the central light ray (the chief ray).
Which cone ? In fact it's a lot more complicated than that. A point in object field send a light cone which intersect sensor=image plane in a disc (provided there is no mechanical vignetting, thing you seem unable to understand), yes.
But, as I already said, the chief ray is the less inclined of the disc ONLY in the middle of the sensor. At the border, the chief ray is MORE tilted than some of the border rays.
If the tilt exceeds a critical angle, the rays cannot reach, and therefore are not recorded by the photodiodes.
That's utterly wrong. The transition is PROGRESSIVE (I said that earlier, you did not understand ?), there's no "critical angle after which NO light is recorded".
Ergo, the recorded diameter of that disc is affected by the sensel's acceptance angle, and that recorded diameter can therefore be smaller than the geometric diameter of the light cone at the imaging plane intersection.
Again, this would only be true right at the middle of the sensor, if there was such an "acceptance angle" (which is NOT the case at any angle we're speaking of).
The CoC is also a disc, and is conceptually and physically identical to the disc formed by the intersection — discussed above — of the light cone and the imaging plane.
Not true. CoC is the diameter a disc can have on the sensor and yet be considered ponctual by an observer placed at the right distance of the printing. When the light cone of an object point intersect the sensor in a circle which is smaller than CoC, then it is in focus.
Ergo, a sensel with a limited acceptance angle will record a disc that is smaller than the disc recorded by a medium like film that hasn't any acceptance angle limits.
Not true. At most you'll have more vignetting, but appearently this "pixel/sensor vignetting" is always weaker than the cos4 law.
A smaller disc, in CoC terms, is a sharper, less blurred disc. If the constitutive points of an image are sharper, it means that the sharpness zone in the object field, i.e. the DoF, must be deeper. Ergo, a sensel with a limited acceptance angle necessarily results — as Mark Dubovoy correctly points out — in a deeper DoF than you'd get with film.
Not true. You're totally confused here, it makes absolutely no sense.
The photozone.de OOF disc samples, while not ideal as they haven't been taken at the center of the imaging field, provide a good measure of the plateauing of the disc's dimensions at a dimension corresponding to about f/1.5
Wrong. Their vertical size is approximately the same than at f/1.5, BECAUSE OF LENS MECHANICAL VIGNETTING AND NOTHING ELSE, but if you were honest, you would point out that their horizontal size is really what's expected for f/1.2 lens. And it proves you're wrong.
And had this crop been taken at center of the frame, you'd see a perfezct circle, the size you except to have for f/1.2 (unless ther is mechanical vignetting due to the chamber, it sometimes happens as I said earlier).
Considering the typical price, size and weight differentials between a f/1.2 and a f/1.4 lens, the fact that — when used on a DSLR like the Canon 5D2 — the effective speed of an f/1.2 lens, as well as its DoF and bokeh might be equivalent only to that of a f/1.5 lens is a quite relevant observation on a photo forum.
Except this "might be" is in fact a "is not".
The apparent deformation affecting the exit pupil at larger image heights — that is, at points far from the image center — is essentially an elliptical one on photozone.de's pictures. Elliptical deformations affect the dimensions of a circular exit pupil only along one axis, and quite valid dimensional measurements can thus be made along the axis unaffected by the elliptical squeezing.
Yes, and had you been honest you would have seen only vertical size is smaller than expected. Horizontal size is fine.
These photozone.de measurements are tangible and totally consistent with the physics of light cone propagation and microlens acceptance angle limitation models.
Yes, and measuring these disks along horizontal axis prove that it's really a f/1.2 bokeh.
I'm laughing at you saying things about "physics of light cone propagation" when in fact you fail to understand even the simplier arguments. "microlens acceptance angle limitation models" is just b***s*** when you talk of 30° angles. It's an issue only for a lot higher angles, and even so, cos4 law is a waaaay bigger issue.
All your assertions, OTOH, are unsubstantiated, including the one that a test with the NEX-5 and a 40mm lens of unknown exit pupil distance is somehow relevant to judge a DSLR's sensel's response to a f/1.2 cone of light.
I'm laughing. Really. "unsubstantiated" describes very well your own posts. Mine consist of facts I've checked, or when it's not I say it.
The exit pupil is not unkown, you failed to read it was between 35 and 45mm ? Yes, I measured it, because I know how to do...
The diagonal of an APS-C sensor like the one used in the NEX-5 is 28mm. If we assume, as you do, that the lens' exit pupil distance from the imaging plane is 40mm, the chief ray's angle in the corner has a tilt of arctan(14mm/40mm) — i.e. corresponding to the tilt of the marginal rays of a light cone of a 40mm/28mm = f/1.4 lens.
Yes, you're right, for once ! But I'm not "assuming", I don't "assume" things or I say I do. I measured it.
So, even if the NEX-5 had no offset microlenses — something that is impossible for me and you to know, — your assertion that your f/1.4 NEX-5 thought experiment "proves" that ray tilt cannot be a vignetting factor with a f/1.2 lens is totally irrelevant.
The fact you don't know that doesn't mean nobody knoes. I do know Nex has no offset microlenses. And I proved that tilted rays are a totally irrelevant issue for f/1.4 lenses with that lens/sensor combination.
And read one of my above post again : I also measured a 50~55mm exit pupil for m 50/2.8 macro Sony lens, and on FF sensor (Alpha 850/900) it has no vignetting. Meaning for f/1.2 lenses (the angle is almost the same), this issue is irrelevant too.
Obviously, if the NEX-5 had offset microlenses, your thought experiment would be even more irrelevant, as the corner sensels' sensitivity to the chief ray's tilt angle would be even less observable.
Except it doesn't have. And I'm not guessing, it's a fact.