If you are curious about boom microscopes here is mine.
It works great with my lathe or anything else you need it for.
It has 10 " of travel up & down and 10" in and out & you can tilt the head or turn it side to side.
One of the eye pieces has a scale built into it so I can judge the size of the object I am looking at.
The box along side of it is a Microscope Light of 25W. it will adjust to any angle and I can use it with my Lathe too.
The scope is a heavy sucker as just the base weights 25 Lbs.