On Sat, 2021-08-14 at 11:29 -0700, Dave Stevens via users wrote:
Patrick, reading through the thread I wonder if you are not trying
to
solve digitally what might be an analog issue. Why not stop by an
opticians shop and see if a simple corrective lens would help. I
suppose you could rig an attachment somehow.
While that's essentially true, and I posted before about the reasons
why it happens (using an extremely wide-angle lens to try and get a
wide angle of view on a tiny sensor), trying to fix that optically
faces various hurdles.
To fix it externally, you'd need an accurately made and placed lens to
counteract the distortions of the camera's built-in lens.
To fix it properly, you'd really need one of:
* A camera with a less-wide-angle lens, and a larger image sensor,
which would mean a less miniaturised webcam on the whole (though not
really that much of a problem - it doesn't need to be huge).
* A wide-angle lens that's been built to avoid fish-eye distortions,
which would mean a more expensive webcam (most of them are knocked
up with cheap components and lenses).
* A camera that processes the image to change the fish-eye distortion,
again a more expensive camera. Many manufactures like to pass the
buck on improving their products, getting the computer to handle
their problems with software, and needing special drivers. You find
that kind of thing a pain when your computer software installation
has moved on since they created their webcam, but never updated
their own software.
Trying to get a very wide angle image on a tiny sensor is hard to do
well. Some special lens approaches can remove some of the distortions
in just one axis. If you were to look at the walls and roof of a room
shot through one of them, you might notice the ceiling looks straight,
but the walls are still bowed.
And then there's the issue of you might be able to make things look
fairly undistorted at one distance from the camera, but if you moved in
closer, the distortion comes back again.
I work in video production, and this issue has been a problem for
decades. Earlier cameras used large image sensors, and good lenses. As
the years went on, they kept shrinking the image sensors (yet the
studio and on-the-shoulder news cameras stayed virtually the same size,
so there was no real need to shrink the sensor). As the sensors got
smaller, it became harder and harder to take wide-angle shots indoors.
In small rooms you couldn't step back far enough to fit everything in,
so you had to use a wider-angle lens. Then when you went outdoors, a
wide-angle lens was very susceptible to lens flares getting into the
glass.
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