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  1. #11

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    Quote Originally Posted by dpurdy View Post
    To be absolutely absolutely correct, the image is upside down but not backwards.
    Wrong. The image on the ground glass is upside down and backwards. It's the laws of physics. Look up how a lens projects an image.
    Bruce Watson
    AchromaticArts.com

  2. #12
    Paul Cocklin's Avatar
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    Bruce, not that it's any of my business, but I think you're flipping the image and then reversing it, and dpurdy is rotating the image. In both cases, left is right and up is down. What a crazy world we live in.

  3. #13
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    If you stand on your head and look at the image it isn't reversed. It isn't backwards. However it does feel backwards just to look at the image. Because things pointing "left" in right side up orientation will be pointing "right" when upside down. Actually it might be easier if the image was both upside down and backwards because in standing there composing the upside down image I quite often reverse it in my mind as if I could lift the image from the bottom straight up to the top. But it must be rotated.

    The reason an image in a WLF is right side up and backwards is because it is bounced off a mirror. You could do the same thing with your view camera. Hold a mirror under the image angled so that you can see it, it will be right side up and backwards.

    If the image on a ground glass were actually upside down and backwards, you could hold a mirror under the ground glass angled for you to see and it would be right side up and oriented correctly.

  4. #14
    Paul Cocklin's Avatar
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    Quote Originally Posted by dpurdy View Post

    If the image on a ground glass were actually upside down and backwards, you could hold a mirror under the ground glass angled for you to see and it would be right side up and oriented correctly.
    Incorrect. The mirror would not reverse side to side, it would only reverse up and down.

  5. #15

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    Quote Originally Posted by Paul Cocklin View Post
    Bruce, not that it's any of my business, but I think you're flipping the image and then reversing it, and dpurdy is rotating the image. In both cases, left is right and up is down. What a crazy world we live in.
    I'm not flipping anything. The lens projects an image that is both upside down and backwards. This is just simple physics. All lens systems do this, from the human eye to cameras.

    The reason DSLR camera use a pentaprism is that to "correct" the image in the viewfinder they have to flip it twice -- once vertically, then again horizontally.
    Bruce Watson
    AchromaticArts.com

  6. #16
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    Well this is all good fun right? Perhaps just a different way of thinking of the same thing. But if you aim your view camera at a word that of course reads left to right, when it gets projected onto your ground glass it is upside down. If you stand on a chair and turn your head upside down, the word will still read correctly. It won't look like a mirror image because it is only upside down and not both upside down and reversed. IF you hold a mirror under the ground glass while you stand behind the camera and angle the mirror up so you can see the image as if it is right side up, it will be reversed and the word will read backwards.

    This is all humorous and a bit difficult to explain, but I am sitting 10 feet from an 8x10 camera on a still life set and there is no question that what I am saying is correct. My flowers which point to the left in reality are upside down and thus pointing right in the camera. If they were both upside down and reversed they would point to the left in reality and still point to the left when upside down.

    I think we are just stating the same thing differently
    Dennis

  7. #17

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    Quote Originally Posted by dpurdy View Post
    If the image on a ground glass were actually upside down and backwards, you could hold a mirror under the ground glass angled for you to see and it would be right side up and oriented correctly.
    Nope. You'd have to flip it twice. Once vertically, once horizontally. Which is why there are pentaprisms in DSLRs. They have to flip it twice because the image is both upside down and backwards.

    This is clearly beyond my ability to explain to you. Such is life; I'm not a teacher. Find someone near who uses a view camera and they can give you a demonstration maybe. Or a local physics teacher can show you maybe.

    BTW, if you are standing on your head looking at the ground glass, it's you who have flipped twice. Once horizontally (which puts you on your head looking away from the ground glass) and once vertically (flips you 180 degrees so you are looking at the ground glass).
    Bruce Watson
    AchromaticArts.com

  8. #18
    dpurdy's Avatar
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    Quote Originally Posted by Bruce Watson View Post
    BTW, if you are standing on your head looking at the ground glass, it's you who have flipped twice. Once horizontally (which puts you on your head looking away from the ground glass) and once vertically (flips you 180 degrees so you are looking at the ground glass).
    What if I just do a cartwheel and stand on my hands. I am only rotated and not flopped. Just once.
    Dennis

  9. #19
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    If I could do cartwheels, I wouldn't care what the image looked like.
    WYSIWYG - At least that's my goal.

    Portfolio-http://apug.org/forums/portfolios.php?u=25518

  10. #20

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    I will attest that the Cambo reflex mirror will end up with a right side up but backwards image.
    "There are a great many things I am in doubt about at the moment, and I should consider myself favoured if you would kindly enlighten me. Signed, Doubtful, off to Canada." (BJP 1914).

    Regards
    Bill

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