The shoemaker's ball

Your assumption is wrong.

Basically the shoemaker's ball could be used that way, but it would only be imperfectly suitable for that. While enlarging, balls distort the image, which would be not very favourable for work. If you look closely, you will see, that the wood cutter uses a permanently mounted magnifying glass.

Indeed, the shoemaker's ball was used to work better with the natural light. Before electric lighting was invented, it was very difficult to light rooms selectively and uniformly. If, in some cases, candles and gas lamps were not useful, people tried to utilise the available natural daylight in the best way possible.

But in what way was the shoemaker's ball used exaclty?

a) The ball was used in the morning to distribute the sunlight which was still shining selectively. The whole room was illuminated by the shoemaker's ball.

b) People used the shoemaker's ball at lunchtime to deflect the bright, dazzling light of the sun.

c) The shoemaker's ball was especially used in the evening to focus the light, which was still available during dusk, for work.