Ironing board.
Height adjustable, collapsible, multi use & it's free: you already have one.
Why an ironing board you ask?
As I viewed objects higher in the sky and had to adjust the height of my stellar chair to suit, it annoyed me that I couldn't reach the table to write any observation notes down. So Les Dalrymple (contributing editor of AS&T mag.) came to my aid and said that's what many people use including himself.