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Thread: normal lenses

  1. #51

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    I don't think Nikon ever claimed 100% in all circumstances for the F or F2. It claimed 100% with a 50mm lens at inifnity.

  2. #52
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    Quote Originally Posted by gleaf View Post
    Normal essentially is what you normally see when you look. Or near when focal length equals the diagonal of the selected image size.
    interesting that our eyeballshave a focal length of about 17mm in average.the aperture ranges from f/2 to f/8 from dim to bright light but I don't know what the film format is
    Regards

    Ralph W. Lambrecht
    www.darkroomagic.comrorrlambrec@ymail.com[/URL]
    www.waybeyondmonochrome.com

  3. #53

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    An old thread but...

    Ralph, our eye vision is essentially ultra-wide. My peripheral vision used to be significantly greater than 180 degrees (now it's less) but that's just the way my eyeballs see, not the way my brain sees. Our human brains concentrate our attention on primarily the center few degrees of what our eyes see... almost like having long lenses rather than wide. However, we move our eyes in all directions and our brains "piece together" a fuller view of our surroundings. It's a far more complicated process than I care to study about.

    I'd say, for most folks, the age-old way of calculating lens normal focal length works fairly well. For me, I think I see wider than that but I do tend to look around a bit more than most folks so maybe that's why. I also tend to prefer wider horizontal images at 1:2 or 1:2.5 ratios moreso than other formats perhaps because in the real world I find it easier to turn my head right/left and move my eyes horizontally rather than move my head up/down and move my eyes vertically. So I guess I have a less tall and wider view of the world.

    At any rate, our "vision" is more of a brain thing than the actual view seen by our eyeballs.
    Last edited by Old-N-Feeble; 11-27-2014 at 08:52 AM. Click to view previous post history.

  4. #54
    KenS's Avatar
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    ‘bubble thinks’… wait a few…

    Was not the 35mm film frame of the day 24mm by X mm wide since it went through the ‘movie’ film gate in a different direction. The ‘diagonal’ of the frame is now ‘smaller’ that what we get with a 36 x 24mm image area and should we now ‘disregard’ that aspect ratio as a function of ‘normal’ field of view?

    Ken
    There are holes in the sky where the rain gets in,
    But they're ever so small that's why rain is thin.
    Spike Milligan.

  5. #55

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    ^^^ That's not what I wrote.

  6. #56
    Peltigera's Avatar
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    Movie film is 24 x 18 but still 35 mm format has usually been 24 x 36 (24 x 24 and 24 x 32 not uncommon).

  7. #57

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    Wooooa Batman another old thread resurrection.

    Cost is the big driver 6x6 cameras have similar focal length rule sets, 6x7, 6x9, etc.

    Technology has improved optical glass with

    refractive index 1.9, wide range of dispersions
    multi coating
    high refractive index glass fluid at very low melting temperatures, high precision ceramic molds
    poly carbonate
    CNC machines

    Only a few design innovations, (like Konicas 40mm Pancake patent)

    Ive no problems with OM1s with the x0.9 finder magnification eye relief and eye glasses, in dim light I need to wind the variable dioptre of OM4s to one extreme to use matt/micro focusing, with my current spec prescription.

    Nikon F and F2 were expensive for the additional tolerances needed (and materials for motor drive use).

    Robin

  8. #58
    ic-racer's Avatar
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    Quote Originally Posted by RalphLambrecht View Post
    a 'normal focal lengthlens is typically defined as havinga focal length equal to the film-format diagonal. in case of 35mm film that is close to 43mm. so, why, I ask don't we see lenses with that focal length?; we have many close to it; 35 or 50mm,but I've never seen 43 or ;let's say 45mm.why do you think that is?I use 35 and 50mm a lot and can see 43 or 45 having an advantagein viewing angle and weight over the typical 500mm normal.confused:
    If you look at the long dimension of the contemporary 35mm format frame opening, it forms a square with a diagonal of 50mm. This is just an observation and it does not answer your question.

  9. #59
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    Quote Originally Posted by Xmas View Post
    Wooooa Batman another old thread resurrection.

    Cost is the big driver 6x6 cameras have similar focal length rule sets, 6x7, 6x9, etc.

    Technology has improved optical glass with

    refractive index 1.9, wide range of dispersions
    multi coating
    high refractive index glass fluid at very low melting temperatures, high precision ceramic molds
    poly carbonate
    CNC machines

    Only a few design innovations, (like Konicas 40mm Pancake patent)
    +1

    Add to your list:

    Extra low dispersion glass comparable to Fluorite
    Anomalous dispersion glass
    Injection-Molded non-glass aspherical lenses (Canon)
    Molded glass aspherical lenses (Canon)

    Design innovations since the 60s:
    Extreme ultra-wide-angle lenses like the 220° fisheye (Nikon)
    Floating elements (Nikon)

    Design innovations since the 80s:
    Diffractive optics (Canon)
    Image stabilization (Canon)
    Designs with Inner element focusing, particularly for AF use... for example the Canon FD 85/1.8 is very different from the following EF 85/1.8; the former is unit focusing while the latter moves an internal group for focusing.
    This Nikkor lens is so good... that it should be labeled as a Canon lens!

  10. #60
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    Quote Originally Posted by ic-racer View Post
    If you look at the long dimension of the contemporary 35mm format frame opening, it forms a square with a diagonal of 50mm. This is just an observation and it does not answer your question.
    Huh?...opening the back of my Olympus OM-4 I measure 43mm diagonal opening.

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