You use different lenses underwater because the speed of light is different

Discussion in '35mm Cameras' started by Dave Hillstrom, Apr 24, 2006.

  1. You can't use regular lenses underwater, that's why you always see
    special cameras on ocean documentaries and such. People think it's
    because they need to be waterproof but the real reason is the speed of
    light underwater is different than in air and it makes the light bend
    at different angles through the lenses.
    Einstein proved it.
     
    Dave Hillstrom, Apr 24, 2006
    #1
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  2. Brilliant.
    groups adjusted.
     
    John McWilliams, Apr 24, 2006
    #2
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  3. Dave Hillstrom

    Mark² Guest

    Uhhhh.....

    Thanks(???)
     
    Mark², Apr 24, 2006
    #3
  4. Dave Hillstrom

    Scott W Guest

    So your thinking is that before Einstein people did not know about
    this?

    Scott
     
    Scott W, Apr 24, 2006
    #4
  5. Dave Hillstrom

    Roger Guest

    You should really be posting this sort of material in

    This stuff will go down a treat.
     
    Roger, Apr 24, 2006
    #5
  6. As if he needed encouragement!

    groups adjusted.
     
    John McWilliams, Apr 24, 2006
    #6
  7. Dave Hillstrom

    dweeb Guest

    Another moron in the diving world.
    Thanks PADI!
     
    dweeb, Apr 24, 2006
    #7
  8. Dave Hillstrom

    cjcampbell Guest

    So, I suppose that is also the reason you need different lenses to take
    telephoto pictures than the lenses you would use for wide angle. Light
    from different distances travels at different speeds? No doubt this is
    due to the fact that light traveling from farther away has to go
    through more haze, so it passes through more water on the way to the
    camera. It would explain depth of field, too. A lens set at a
    particular focal length can only bend light traveling at a particular
    speed at the correct angle. Light that is going too fast or too slow
    would, of course, bend at the wrong angle and thus the foreground and
    background are out of focus. That being the case, you would also need
    special lenses in space, where light does not travel through any water
    at all.

    Or maybe it is just wrong to encourage this nut.
     
    cjcampbell, Apr 24, 2006
    #8
  9. Dave Hillstrom

    Benoit T Guest

    dweeb a écrit :
    No, No. PADI have specific courses for each model of lens ...
    that's why ... ;-)

    Benoit.
     
    Benoit T, Apr 24, 2006
    #9
  10. Dave Hillstrom

    Prometheus Guest

    No, it is you who is wrong. Light DOES travel at a lower speed through
    water than air The refraction at the water/glass interface of the front
    element when immersed in water is very different to the air/glass
    interface when in air. The effect of water vapour in air is much, much
    less; although droplets will cause random refractions and make objects
    blurred.
     
    Prometheus, Apr 24, 2006
    #10
  11. Einstein gets blamed for everything.......
     
    William Graham, Apr 24, 2006
    #11
  12. Dave Hillstrom

    Lionel Guest

    **** off Bowtie.
     
    Lionel, Apr 24, 2006
    #12
  13. At last someone has mentioned the word "refraction". We learned it at
    school, 65 years ago! What DO they teach kids nowadays?

    Dennis.
     
    Dennis Pogson, Apr 24, 2006
    #13
  14. Dave Hillstrom

    cjcampbell Guest

    Okay, seriously, I know that the speed of light changes slightly as it
    travels through water, glass, and just about anything else. That said,
    the lenses used in underwater photography work perfectly well on dry
    ground, in space, or just about anywhere else.

    I should have known that attempting any humor at all on Usenet is
    dangerous...
     
    cjcampbell, Apr 24, 2006
    #14
  15. cjcampbell wrote in part:
    YOU'VE GOT PEOPLE SKILLS, DAMMIT!
     
    Unclaimed Mysteries, Apr 24, 2006
    #15
  16. Dave Hillstrom

    Celcius Guest

    Hi Dave!

    Please explain why on my Nikonos camera, I had a 35mm lens which could
    photograph both underwater and and land? Just curious. There was also a
    28mm for underwater only as well as others. The only other factors that
    I know of is that underwater, things seem closer than on land and warm
    colours disappear as you go deeper.

    Marcel
     
    Celcius, Apr 24, 2006
    #16
  17. Dave Hillstrom

    Lee Bell Guest

    Yes you can.
    Nikon proved it.

    You should not cross post like this.
    You proved it.
     
    Lee Bell, Apr 24, 2006
    #17
  18. Funny thing. You are about half right, almost.

    Yea, light travels at different speeds. It even is different in glass,
    or different kinds of glass. That has been known for a long time.

    It does means that the focusing scale marked on the lens is not going to
    be correct, but it does not mean the lens needs to be changed.
     
    Joseph Meehan, Apr 24, 2006
    #18
  19. Dave Hillstrom

    Mike Guest

    This is the very first worthy answer in this thread.
    And most probably the last.

    Mike
     
    Mike, Apr 24, 2006
    #19
  20. Dave Hillstrom

    Lionel Guest

    Yes it is, because he has zero interest in the topic & is posting only
    to generate as many responses as possible. Please don't encourage him.
     
    Lionel, Apr 24, 2006
    #20
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