Finderscopes are essential in finding objects at low power for polar alignment or quick spotting.
The user must properly align the finderscope to the eyepiece, so whatever you see in the finderscope will be in the eyepiece. Once the object is found, use a low power eyepiece to refine the alignment.
Included as standard equipment on ETX-125 telescopes, the 8x25 right-angle viewfinder permits comfortable 90° viewing with ETX-90 telescopes as well. The #825 fits into the same bracket as the 8x21 finder supplied with the ETX-90 telescopes.
The finder's wideangle 7.5° actual field facilitates object location. Precise focusing of the image is accomplished with a helicoid mechanism.