Recent content by jt7747

  1. J

    Optics question - eyes and cameras, and the mythical 50mm lens

    I'm afraid it's not a claim, it's basic science. Have you checked out those introductory textbooks I cited earlier? If not send me your email address because I have a few pages scanned which will help you understand a little better. You are almost there. When you 'get it' you're going to kick...
  2. J

    Optics question - eyes and cameras, and the mythical 50mm lens

    It is fortunate that you do understand the concepts. But surely you must appreciate how many photographers latch onto the 'focal length changes perspective' bandwagon without out actually understanding why? Surely it would be better for people to actually understand that perspective changes due...
  3. J

    Optics question - eyes and cameras, and the mythical 50mm lens

    Correct. Only a fool would embark upon a portrait shoot with a wide angle lens. That's why most will use something like an 85 or 135 mm equivalent. Of that there is no doubt. But it would be twice the fool to claim that wide angle lenses are unflattering, or the oft-cited corollary that...
  4. J

    Optics question - eyes and cameras, and the mythical 50mm lens

    Exactly. I agree. Now you can see why it's nonsense when people confound focal length with 'flatteringness'. Experienced photographers (who really should know better) will swear blind that you simply can't shoot a portrait with a wide angle lens, no matter what. They attribute some mysterious...
  5. J

    Optics question - eyes and cameras, and the mythical 50mm lens

    Hmmm. And what is double confusing is that viewfinder magnification is expressed in terms of a 50mm lens. So 1x doesn't mean 'neutral mag' it just means it matches a 50mm lens. Manufacturers tend not to scale this is for 1.6 x crop bodies, so take any specification with a large grain of salt.
  6. J

    Optics question - eyes and cameras, and the mythical 50mm lens

    Other good books for the perspectivally unenlightened are "The Camera" by Anselm Adams and "Amphoto guide to lenses" by Keith Bancroft. Both spell out very clearly that the compelling idea of perspective distortion is a myth, and highlight the importance of a picture's centre of perspective...
  7. J

    Optics question - eyes and cameras, and the mythical 50mm lens

    There is no such thing as variable depth perspective due to a lens. All standard rectilinear lenses record perspective in exactly the same way a human eye does. Telephoto lenses do not 'warp' perspective. This is not a form of distortion. It is basic geometry and angles that define why near...
  8. J

    Optics question - eyes and cameras, and the mythical 50mm lens

    But how? The reason this confusion is so widespread is because people misattribute perspective effects to the focal length of the lens. If people were to realize that camera-subject-distance affects perspective, not focal length, then the world would be a better place. It is 100% to do with...
  9. J

    Optics question - eyes and cameras, and the mythical 50mm lens

    But if your D200 had different viewfinder prism with different magnification, this experiment would be worthless wouldn't it? Viewfinders come in different shapes and sizes, some have different coverage and magnification. I submit that matching the real world to the viewfinder tells you more...
  10. J

    Optics question - eyes and cameras, and the mythical 50mm lens

    I'm afraid I am totally right, and my position is backed up by all the reputable photography books. Unfortunately there are 100s of less reputable photography manuals that give advice such as "use a 135mm for portraits because it will make noses look more flattering" That is 100% wrong. The...
  11. J

    Optics question - eyes and cameras, and the mythical 50mm lens

    Thanks for your input, but I confess I'm a little confused. The 'depth perspective' is governed by the camera position, not focal length. Changing focal length while standing in the same spot does not alter the perspective: angles to objects in the scene are identical, as are relative sizes...
  12. J

    Optics question - eyes and cameras, and the mythical 50mm lens

    Hmmm, thanks folks. I'm getting conflicting messages. One thing is absolutely clear. Focal length doesn't impact perspective. Not one bit. The reason people tend not to use wide angles for portraits is that, to fill the frame with the subject's head and shoulders, a wide angle would force you...
  13. J

    Optics question - eyes and cameras, and the mythical 50mm lens

    Oh yes - one more thing, thank you schip for pointing out the normal lens. This is a useful measure, but since it's based on a diagonal it doesn't account for aspect ratio. The diagonal of a 4:3 sensor is rather different to that of a 16:9 sensor, even though all lenses cast image circles, not...
  14. J

    Optics question - eyes and cameras, and the mythical 50mm lens

    Thanks folks. Yes - people will swear blind that telephotos compress perspective, and wide angles distort it. It's easy to confuse the so called properties of a lens with the camera-to-subject distance, which is the root of perspective. Also significant is the need to view prints from the...
  15. J

    Optics question - eyes and cameras, and the mythical 50mm lens

    Eyes and cameras - a topic that has been troubling me Hi all. This is my first post. I'm seriously thinking about applying to optometric college in the fall. I'm trying to improve my knowledge as much as possible of the area, and one question that keeps coming up (I'm a hobby photographer...)...
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