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Lecture 16: Cameras and Lenses (14)

How are iPhones today able to switch from "normal" angle to various degrees of "wide angle"? Do they have different focal lengths or sensor sizes that they switch between?


It looks like 104 degrees is more like 180 degrees in this diagram. Is this just not drawn to scale, or is there another way to interpret that?


I did a bit of google-ing and it seems like the wide-angle mode on iPhones is possible because the three cameras on the back all have different focal lengths. The wide-angle one has a 13 mm focal length, which can capture a 120 degree field of view. The normal camera has a 26 mm focal length.


I agree with ecorriere that this diagram doesn't draw 104-degree FoV correctly. If a lens has 180-degree FoV, it has to be a fisheye lens. Some fisheye lenses feature a really wide FoV. For example, Nikon's 6 mm circular fisheye lens actually has 220-degree FoV.


@kristinechen8 For iPhone models with multiple lenses, those lenses do have different focal lengths. For models with just one camera, the same effect is simulated via digital zoom.


I think it's very interesting to think about a camera view in these terms, I wonder what adding attachments to you iphone camera add that changing the view on your phone can't do


Based on the diagram, it seems like a longer focal length also corresponds to being able to capture things from a much larger distance away. What's the math behind this?


A larger focal length narrows the field of view. So objects that are smaller (farther objects) in an image shot with a smaller focal length are magnified when shot with a larger focal length because that object now occupies the entire field of view.

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