I'm looking at Televue NP101. Went to browse through the specifications but did not find any write up on the back focus.timatworksg wrote:Well alot has already been said...and they are all great pieces of advice!
Yes,....longer back focus allows the use of equipment in between the scope and Eye Piece/CCD Cam such as filter wheels, extenders, Off Axis Guiders, 2" Diagonals...etc etc. All these extra in-between's extend the scopes length and the long back focus allows for this.
Shorter back focus, such as newtonians loose out. Mods and improvements have been made such as bringing the primary mirror forward or a shorter focuser body (found on Imaging Newtonians)..however don't benefit from to many in-betweens as it is limited.
Some scopes have an screwed on Focuser section (such as the Stellarvue SV102, which has a screwed on back end which allows one to shorten the scope length for the provision of a Bino viewer).
So as already said...if your an imager....long focus is a plus! Allowing you to add the in betweens needed for imaging (but increases weight and balance). Also larger Refractors have long scope lengths...which with these in-between's increases it a fair bit! Smaller refractors (60, 80, 90mm) are nice and balance out well with the extras, but you get a smaller FOV...trade off depending on your imaging needs (wide field or up-close).
Scopes like the WO ZS66 have short back focus...where as the Megrz is longer.
Hope you get it all in....to play safe...get long focus...lol! Diagonals and extenders are nice bits to have as extra equipment and can benefit in the long run of your hobby!
Does anyone know of the amount of back focus for this scope?
Thanks !!