Unusual question about angle of view

Discussion in 'Beyond the Basics' started by nyhus, Apr 3, 2017.

  1. nyhus

    nyhus TPF Noob!

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    This might be an unusual and stupid question, and i am unsure if this is the right place to post.

    In a normal photo without fisheye lense, are the angles in the photograph evenly "distributed"? (in lack of better words)

    what i mean is, if the angle of view is 60 degrees (blue line), that means it is 30 degrees (red line) from the center to the right of the view.
    But is it also 30 degrees from the top middle to the top right of the view (yellow line)? also does it mean that it is 15 degrees from the right to halfway to the center of the view (green line)?

    Also, lets say the aspect ratio is 16/9. could you then say that its 60/ (16/9) = 33,75 degrees from top to bottom (purple line)? and could you use pythagoras ((60^2)+(33,75^2) = 68,841^2) and say that the diagonal is 68,851 degrees (pink line)?

    Are these assumptions right or am i missing a big point here?

    I hope someone can answer, and sorry if its a stupid question :)


     

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  2. astroNikon

    astroNikon 'ya all Bananas I tell 'ya Supporting Member

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    I'm not sure on the exact answer you are looking for, and there are a few more ppl here that are very technically savvy.

    But an image should be consistently spread across the sensor properly to represent the specific lens. There are distortions though which can deviate from what it should be, which you'll find more distortions (such as the sides leaning in on UWA lenses) on cheaper lens and less so on more expensive higher quality lenses. There are a variety of different types of distortion which can "skew" that perfectly distributed image. ==> What is Distortion?

    But Angle of View is specific for the lens, such as this article from Tokina and their public brochure.
    Tokina-AngleOfView-pg24.jpg

    Additionally, you'll want to look at the Perspective also which may also skew your understanding of how lenses and optics operate
    Tokina-Perspective-pg25.jpg
     
  3. snowbear

    snowbear fuzzy-wuzzy Supporting Member

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    Although the lens may be giving you 60 degrees both vertically and horizontally, because the sensor is a rectangle, you will not get a full 60 degrees in the short side.

    Additionally, aspect ratio can depend on what format is used: ASP-C and full frame still photography, like 35mm film, is 3:2, while a lot of point-and-shoot digital sensors are 4:3. I don't know about video - I don't use it.
     
  4. Alexr25

    Alexr25 No longer a newbie, moving up!

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    Angle of view (AoV) is generally specified across the diagonal of the frame so if the lens AoV is 60 degrees the angle between the center of the frame and any corner would be 30 degrees. Obviously if the image frame is rectangular the vertical AoV and the horizontal AoV would be different and would be less than the published AoV for the lens.
     
  5. Dave442

    Dave442 Been spending a lot of time on here!

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    There is a photography app (actually done for cinematography) that will give you the angles of view.
    pCAM film + Digital Pro.
     
  6. Gary A.

    Gary A. Been spending a lot of time on here!

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    Remember that the lens projects a spherical image. So if the lens and sensor are centered, all should be equal and symmetrical.
     
  7. Alexr25

    Alexr25 No longer a newbie, moving up!

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    Also you can't apply Pythagoras' Theorem to angles, it only works for lengths. You need to specify or calculate the lens focal length and sensor dimensions and then use trigonometry to obtain the angles you are interested in.
     
  8. Alexr25

    Alexr25 No longer a newbie, moving up!

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    The image circle will be symmetrical about the center but that tells you nothing about the image angle of view. You need to know the sensor dimensions and lens focal length to work that out.
     
  9. Derrel

    Derrel Mr. Rain Cloud

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  10. pgriz

    pgriz Been spending a lot of time on here!

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    It also depends on how much alcohol you're imbibed previously. There are some angles of view that absolutely have to be taken from about 3" above floor level. Pro-hint: don't do selfies under those circumstances.
     
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  11. nyhus

    nyhus TPF Noob!

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    Thanks for all the answers! Ill admit, some of them are quite hard for me to understand, hehe. ill try reading them again slowly! But from what i understand my assumptions were wrong, am i right?

    Basically what i want to know is that if one length, lets say 10mm, on the photograph covers 1 degree of view in the center, will the same 10mm length cover 1 degree anywhere in the photograph, and in any direction (up, down, diagonal)? Or will the same length cover different angles depending on where on the photograph and in what direction?
    Try going easy on me, i cant really grasp all of the tecnical camera terms.

    If it does not, does anyone have any good software or ideas on how to make the angles evenly spread across the image?
     
  12. WayneF

    WayneF No longer a newbie, moving up!

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    Yes, a regular camera lens will be linear that way. The property is called rectilinear. Regular lens may have tiny pincushion or barrel distortions, but they are designed to be rectilinear.

    This will happen on a fisheye lens, which is not rectilinear. Different design properties.
     
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