[danrok]

A very wide lens is not necessary.

You need to make a panorama which does the full 180 degrees on the vertical, and 360 degrees horizontal.

That panorama must have a 1:2 aspect, e.g. 3200 x 1600 pixels.

Then you resize it to a square shape, e.g. 1600 x 1600. Squashed horizontally, in other words.

Then you can make it in to a sphere.