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Joined on Nov 9, 2010

Antisthenes' recent activity

  • That would be an excellent "sanity check" of your optical bench measurement results re. the Sony SEL70200GM. Take the (apparently outstanding) new Nikkor 70-200/2.8 E-FL, the (possibly suspect) ...
  • Thanks for the very interesting actual test pictures ! The MTF chart published on the web site for the SEL55F18Z lens has curves for the 10, 20 and 40lpmm spatial requencies. OTOH, the MTF ...
  • A 5-axis IS system typically measures 3 angular velocities (using 3 gyroscopes) and 2 translational, orthogonal linear accelerations (using 2 accelerometers). The three orthogonal rotation axes ...
  • Leaving aside the quite high price, innumerate people like you probably don't understand that — as one bit of DR corresponds to about 6.0206 dB — the claimed 64dB of dynamic range is equivalent to...

  • Yup.

    Frustrated people will always find reasons to complain.

    The Sofort is quite historic, as it's Leica's timid, first foray into what could /actually/ be called "medium format".


  • Consider the two meanings for "visualization" listed by Merriam-Webster:

    1: formation of MENTAL [i.e. abstract] visual images
    2: the act [..] of PUTTING INTO [concrete] VISUAL FORM

    "Meaning 1" is...

  • @stefpix
    > I am wondering if Sony's new lenses are designed by cutting
    > corners and they all focus shift

    Focus shift is essentially caused by spherical aberration (SA). A lens subject to...

  • @Rishi
    > The lens also stopped down even for AF-S/initial acquisition
    > if you pointed it a bright-ish scene - as if the camera is
    > afraid of letting in too much light, which makes no sense


  • .
    > That's a 50mm lens, a standard, boring focal length. [..]
    > it's something that you can put on the camera and take
    > everywhwre with no high expectations.

    The kind of fashionably dismissive...

  • Replied in compl-E-ment
    Simple Definition of compliment : a remark that says something good about someone or something Simple Definition of complement : something that completes something else or makes it better As to ...
  • Note that discussions about the aperture bahaviour of this lens based on Rishi's interesting, but necessarily quick hands-on are fairly irrelevant.

    Sony explicitly states that the A7R2 must be...

  • ../..
    As light field photography demonstrates, imaging systems are becoming, more and more, computational systems.

    An important theoretical limit of such systems is that the mapping mechanism...

  • Your assertion:

    "there exist bijections form R^3 to R^2, you did not have to go to countable sets"

    My reply:

    Such bijections are theoretical constructs — e.g. fractal — that are not computable,...

  • Your assertion:

    "On a more mathematical note, R^2 and R^3 are not isometric, and there is nothing we can do about that."

    My reply:

    As explained above, nothing prevents a 2D surface from being...

  • Your assertion:

    "There is no projection that would preserve distances - it is a trivial thing to figure out. All points on any radial way, for example, will be projected to one, which means zero...

  • Your assertion:

    "The same "distortion free" lens makes your head look like a head of a Martian near the edges and does not preserve angles or ratios of angles/sides not parallel to the image...

  • ../..
    Note that, say, a 24MP full-frame sensor has a pixel pitch of about 6 microns — i.e. about six thousand nanometers. As explained above, there exist optical systems that can project a picture...

  • Nope. It's you who are a bit out of your depth, as demonstrated by your shallow, sweeping statements.

    Your assertion:

    "there is no such thing as a distortion free lens or a lens with...

  • On a more mathematical note, a projection is a mapping. Furthermore, it's far from established that the fabric of the Universe has the cardinality of the continuum.
    At a microscopic scale — e.g....

  • The angles and distances of 3D objects can be preserved by photographing them using a bi-telecentric lens, as used e.g. in machine vision applications.

    With such a lens, given that the entrance...

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