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  1. M

    Focussing: Just Do It!

    It would be an interesting experiment to put astrographic plates of the same field, taken six months apart, under a stereo comparator. I suspect that except only a very few stars are so close enough to “pop out” and appear to be in front of the rest of the field. I’m not sure our eyes would...
  2. M

    Focussing: Just Do It!

    1. No, you have to refocus because the binocular cannot accommodate at all. Its lenses cannot change shape. 2. They work the same as for anyone else. The focus wheel “accommodates” the binocular to your vision. (in the absence of astigmatism, etc)
  3. M

    Focussing: Just Do It!

    I never did that with binoculars or telescopes. I focus on a star, then move to the moon. It works every time, and fiddling the focus never did improve it. Add me to the “If it’s at infinity, it’s at infinity.“ crowd.
  4. M

    Focussing: Just Do It!

    Any idea why?
  5. M

    Focussing: Just Do It!

    Is there fluorescent lighting in the room?
  6. M

    Focussing: Just Do It!

    We had one of those at work, he drove everyone crazy complaining that his computer screen was “flickering” but no one else saw it.
  7. M

    Focussing: Just Do It!

    Don’t birds have four color receptors, instead of our three, or am I confused?
  8. M

    Focussing: Just Do It!

    To be perhaps pedantic, the eye does none of that it is the image-combining and signal-processing center in the brain which “makes” the image out of pulses(?) from the retina via the optic nerve. The eye, like many lens systems, performs better when it is stopped down. In bright sunlight I...
  9. M

    Focussing: Just Do It!

    I seem to recall reading many years ago, that infinity was defined as fifty (50) focal lengths. Perhaps I remember incorrectly. Unfortunately, about the time these discussions get really interesting, they go beyond my ability to understand and follow. :(
  10. M

    Focussing: Just Do It!

    Thank you, Henry. That helped, and I’m going to move on to something else while I still think I understand it. Richard
  11. M

    Focussing: Just Do It!

    Where does that leave observing the sun by projection? What am I not understanding here?
  12. M

    Focussing: Just Do It!

    Alas, you are right. Off to edit. (I could blame auto-correct, but that would be bad form) Thanks for the references. ETA: Fascinating. I got pretty well lost in the first one, which was way over my head, and the second one was easier for me to follow. I like the experiment at the end, which...
  13. M

    Focussing: Just Do It!

    All of the hand-waving and speculation aside, is there any objective measurement of the distance at which a “relaxed” human eye is focused? It strains my credulity that it is 1-2 meters, and I would like to see a citation from the peer-reviewed literature In support of that figure. As for when...
  14. M

    Focussing: Just Do It!

    How?
  15. M

    Focussing: Just Do It!

    When the ophthalmologist dilates your eyes, the drops paralyze the muscles of the iris …… do those drops also paralyze the muscles which change the focal length of the (OEM) lens? If so, at what distance is the eye then focused?
  16. M

    Focussing: Just Do It!

    When you mentioned your son’s (implied) wide range of accommodation together with his visual acuity, I assumed you saw some sort of correlation. I think I must have read too much into the statement, and assumed something which was not there. Richard
  17. M

    Focussing: Just Do It!

    Are we confusing visual acuity with range of accommodation?
  18. M

    Focussing: Just Do It!

    I’d like to see some literature citations on the business of the effects of accommodation on focusing of optics. Has this been investigated systematically? My ability to accommodate is exactly zero, since my lenses are both implants. I, therefor, attribute any differential diopter setting to...
  19. M

    Focussing: Just Do It!

    This stuff is fascinating.
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