Quote:
Originally Posted by littlegreenman
Generally speaking, with popular brands like skywatcher, meade etc, do they make better quality mirrors and lenses now than say 10 years ago?
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Not really, no. The technology has improved - things like adding encoders to do "push to" (dobs), even motorised GOTO and so-on, but:
1. the optics are largely governed by the laws of physics, the materials used, and the quality of the manufacturing.
Not much has changed in 40 years - there are lots of scopes with rather "average" optics, perhaps 10% with exceptionally good optics, and perhaps 20% with substandard optics that are not what most would expect as "diffraction limited".
The mirror coating technology has have not changed in 30 years. Some mirrors have cheap aluminium-only coatings - these have high reflectivity but are soft, easily scratched and oxidise (pinholes develop and grow with time) and need recoating after 2-3 years. Some have exotic metals added to last longer (Beryllium). Others have a quartz or SiO2 overcoat which will last 10+ years, but eventually they too need to be stripped and recoated.
2. The cheaper mounts and tube assemblies - especially the ones sold for budget dobsonians by Skywatcher, Orion and meade - are built down to a minimum price. They will work well enough at first for casual observer, but after a while moisture will get to the MDF or chipboard and they start to go soft or fall apart. The tube assemblies are also very flimsy.
Eventually if you learn a bit more about what is going on you will realise the mechanicals are junk, then strip it to re-use the optics and some of the hardware to build a new dob yourself to fix these issues.
3. The optics in the commercial schmidt-cassegrains - Meade / Celestron - in recent years have been a lot better than they were 10/20/30 years ago. Especially the ACF (Meade) or EdgeHD (Celestron). Prior to these the ordinary SCT's could be a bit of a gamble - there were some good ones among a lot of inferior ones.
4. Maksutovs - the Meade 7" maks had consistently good optics, if you are happy with an f/15 scope. Likewise the Orion/Skywatcher cheap chinese maks in recent years seem to be optically quite good but not always as perfect as they could be. The maks from Intes Micro had very good optics but are hard to find.
5. Then there is Questar, in a class all by itself - perfect optics in the only small telescopes built to last a lifetime - and continue to have no issues with obsolescence after 50 years. But you pay a hefty premium for one of these.
