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Recent content by Omid

  1. Omid

    blackouts at AFOV of greater than 60 degrees- why

    No problem, and you are welcome :)
  2. Omid

    blackouts at AFOV of greater than 60 degrees- why

    Hi Kimmik, Thank you for the clarification. OK, so you experienced blackouts on the smaller size NL models. Your experience could be due to the small exit pupil size and, in addition, spherical aberration of the exit pupil and, further due to vignetting of the field rays. I am afraid your...
  3. Omid

    blackouts at AFOV of greater than 60 degrees- why

    As I said, I have no opinion on whether NL binoculars have black-out problems or not. I don't own these models and I don't follow their reviews or user opinions. So, have you experienced blackouts while looking through Swarovski NL binoculars? And then you have tested their eyepieces for...
  4. Omid

    blackouts at AFOV of greater than 60 degrees- why

    I didn't say anything about Swarovski NL binoculars; what I mentioned are general facts of visual optics :)
  5. Omid

    blackouts at AFOV of greater than 60 degrees- why

    Spherical aberration of the exit pupil is the main cause. Yet, another cause is vignetting of the field beams coming from the edges of field of view. Up to 50% vignetting is considered OK in designing visual instruments: your binoculus might create a nice 5mm circular exit pupil for the central...
  6. Omid

    blackouts at AFOV of greater than 60 degrees- why

    Ed (Elkcub) gave the accurate technical answer in post # 11. I will add one more point: The eye does not see a wide angle field of view all at once as in a wide-angle camera. It rotates and scans the field (the sharp field of view of human eye is about 1 degree). The entrance pupil of the eye...
  7. Omid

    Focussing: Just Do It!

    Hi Lee! Excessive field of view is when the eye doesn't positively see the field stop as a "frame" surrounding the "magnified view". @Binastro: Very nice story! It proves my point ;)
  8. Omid

    Focussing: Just Do It!

    An excessively large field of view will interfere with your perception of horizon. In the natural world, your peripheral vision constantly monitors the position of ground relative to your body. If you look at the world under magnification, your peripheral vision will see (more correctly, sense)...
  9. Omid

    Is "3-D" More Natural in Porros or Roofs?

    Thank you Binastro, Binocularbirdfreak and wdc for your contributions. I am studying effect of magnification on perspective and on stereoscopic vision. Very complex yet interesting topic...
  10. Omid

    Focussing: Just Do It!

    Thank you and sorry for late reply. Yes, that's what it means. The sharp field of view of human vision is only 0.5 to 1 degree wide depending how strictly you define sharpness. This means, in your typical binoculars with 60-degree apparent field of view, only 1/3600 of the visible area is seen...
  11. Omid

    Focussing: Just Do It!

    Less than two months ago, I was invited to a prominent optical manufacturing company in Europe. During my visit, I gave a 3-hour talk on Visual Perception for the company's executives and R&D engineers. I organized my talk in two parts. During part one, I considered the human eye as a camera and...
  12. Omid

    Focussing: Just Do It!

    Thanks! I had not seen this one ;) Here is my current understanding based on all that I have read and learned: As a biological creature who needs to see to function and survive, much of our "world" is outside the radius of 3m for which no accommodation is required. Accommodation is required to...
  13. Omid

    Focussing: Just Do It!

    No. Lag of accommodation refers to the fact that human eye doesn't accommodate enough on objects which are too close and accommodates too much on objects which are far. At some intermediate distance (called the resting point of accommodation, about 80cm to 1.5m), the eye accommodates accurately...
  14. Omid

    Is "3-D" More Natural in Porros or Roofs?

    Hi Henry, First, let me thank you for your extremely valuable post (#1). This is the only kind of content that interests me these days: how looking through magnifying optics affects our perception of space. The exact technical answer to your question is that both models provide diminished...
  15. Omid

    Focussing: Just Do It!

    You are underestimating yourself! The human eye is not a camera. You eye likely has about 1D residual accommodation! French vision scientist Yves Le Grand associates this capability to the retina/brain adaptation to the really high chromatic aberration of the eye's natural lens (which is more...
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