A simplified focusingmechanism for amateurtelescopes, having a smooth spring-loaded shaft which holds the focus tube against four opposing bearing surfaces, and controls its movement.
Origin
It was initially demonstrated to the Crayford Manor House Astronomical Society.
Modern English dictionary
Explore and search massive catalog of over 900,000 word meanings.
Word of the Day
Get a curated memorable word every day.
Challenge yourself
Level up your vocabulary by setting personal goals.