Stargazing Live: Astronomy invention given away free
7 January 2014 Last updated at 15:36 GMT
A retired engineer who revolutionised amateur astronomy has revealed that he gave away an invention for free.
John Wall, from Coventry, created the Crayford Focuser, allowing cheap, smooth focusing of a telescope.
He said: "I don't get any royalties for it but I don't care... The fact is it's all over the planet now."
Stargazing Live celebrates astronomy on BBC Two on Tuesday evening.
Speaking about the invention, presenter Mark Thompson said: "It's really revolutionised amateur astronomy because it's given amateurs the chance to do some really top quality imaging."
BBC Midlands Today science correspondent David Gregory-Kumar reports.