Analysing Orion Observer 80ST’s Optical Tube
The 80ST is an 80mm f/5 achromatic refractor. Being a cheap fast achromat, the scope suffers from a lot of chromatic aberration, which results in blurry images at high magnifications (especially on the Moon and planets) and obnoxious purple halos around bright objects such as the Moon, planets, and bright stars. The 80ST suffers from quite a bit more chromatic aberration than its predecessor – so much so that it is basically unusable at magnifications of over 50x. You’re not going to be seeing much detail in the cloud belts of Jupiter and Saturn with this scope, nor the Cassini division, nor likely anything at all on Mars besides maybe its polar ice cap.
The 80ST’s lens is not multi-coated unlike most decent telescopes in the modern era. It has a simple, anti-reflection coating (if any at all – Orion claims there is one, but I can’t see any indication of it) which means it suffers a bit of a loss of light gathering ability compared to most other 80mm refractors and has more glare problems.
These glare problems are not helped by the horribly bad plastic focuser on the telescope. Nothing about ...