Angle of View for a photographic lens based on image circle and focal length

Result is presented in degrees.

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  • Thanks for the great explanation about lenses I’m looking at your image angle of view for a photographic image circle.
    Quick thing, Focal lengtn: question is misspelled.

    Secondly when I measure my 3010mm Schmidt cassegrain with 301mm aperture, I get a reasonable 6 degrees, but that doesn’t count for the optics of the eyepiece. I would imagine the largest one that uses the whole cone of light, over 50mm?
    I was originally inputting the sensor size, 25mm, which is what I understood from the article that links to this calculator page.
    I am switching between various camera sensors on this and a 1/3 F1 sensor and trying to verify and rationalize the results, for FOV, F, and aperture.

    • Hello, I am not sure if I understood your question. What I can say is that if you use a 3010mm objective capable of projecting an image 25mm in size (be it diagonal of a rectangle or diameter of a circle) the angle of view will be given by the formula featured in this link: Angle of View for a photographic lens based on image circle and focal length But the actual angle of view of your lens (or catadioptric system) is something that depends on its design alone. Whether its image is fully or partially captured by a sensor, film or ocular or secondary system, that is another and independent story. Normally camera and telescope designers make the image making and image capturing part of an optical system coherent, without lack or surplus of image to be handled by the capturing part. Finally, the aperture is yet another theme and has to do with the question of how much light is captured by the lens in relation to how far it travels until an image is formed. I don’t know if this helps but these are concepts that are always valid and should always be considered.

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