Orion Optics 8x50 straight-through finderscope
The Orion Optics 8×50 straight-through finder is robust and well made. It comes with a single mounting bracket that has a spring-loaded holder and two plastic screws for adjustment.
These fit into a groove in the main finder tube and generally worked well, although the plastic screws could become chewed if you over-tightened them.
Its field of view was excellent – at about 5° wide, at least 85 per cent of it was sharp, while the crosshairs were sharply defined and centred.
Focusing (if required, but not necessary for us) was done by loosening a section of the front lens assembly and then turning the front lens, retightening it afterwards to maintain focus.
Although there was no eyecup to protect the eyepiece, we still had a clear and unobstructed view, although this may be an issue in dewy conditions.
Finding objects was a breeze: Struve 747 was cleanly split to give good resolution, and we were able to locate and centre the Crab Nebula, which is dim at mag. +8.4, and small at just 8’ x 4’ across.
This finder allowed us to locate quite a few deep-sky objects, and gave good views of the larger and brighter ones.
This review originally appeared in the March 2007 issue of BBC Sky at Night Magazine.