Daytime all-sky camera?

[Maury Markowitz]

Hello everyone, first-timer here. Forgive me if this is a dup, something odd happened while positing.

I have a non-astronomy project but I think the people here are the best to ask. I want to put a camera at the top of the mast of sailboat and take all-sky images onto my iPad in the cockpit. The electronics I can do, Arduino makes these sorts of things so easy!

My question is about the optics, which is why I am here. I have seen many threads about making high-end all-sky cameras. Most of these use a lens attachment and a dome. My question is whether the lens is needed? Some of the small XVGA-level cameras have the sensor exposed, and I'm wondering if the dome alone would focus properly onto such a sensor?

Or am I missing something here, optically speaking?

[Gina]

Hello and welcome to SGL ?

The dome is only for protection it doesn't focus the light.  It might bend it very slightly which means the focus of a fish-eye lens changes very slightly when the dome is added.  For the lens, you need a very short focal length, called a "fish-eye".