Dobsonian mirror quality: Industrial versus Custom

[felix9000]

  This is something I know very little about, but I'm glad I'm here now to get pointed in the right direction...How much of a difference will a decent mirror from a dedicated optics company or talented individual make versus the mass-produced versions that come with cheapo dobs?

  So I guess what I'm getting at, too, is what you get when you go with a company like Obsession....Sure the bases are handmade, and great, but for the casual observer, is the difference in price warranted when it comes to the primary mirror?

  What could I expect to see in image quality changes from one to the other?

  The main reason I'm asking is we have a local producer of custom dobs and kits near me https://www.astrosystems.biz/ and the owner/operator offered me a 12.25" primary at f/4.77 with a secondary for 850 bucks, that usually goes for 1400. So I was looking at buying a truss-tube dob in that size-range by summer's end, and am just wondering if I should spring for the decent mirror and build my own mount, or adapt a store-bought mount and put the better mirror in.

[Scooot]

Hi felix, have a read of some of orion optics info http://www.orionoptics.co.uk/OPTICS/allaboutoptics.html

http://www.orionoptics.co.uk/OPTICS/pvexplained.html

Usually with a custom mirror you receive a report setting out the quality of a mirror so you can buy with a degree of certainty. You don't with a mass produced mirror, so unless you have it tested you don't know it's quality. A massed produced manufacturers mirror would normally be near the minimum limits required for good viewing but whether it is or not will be dependent on their quality control. Some might be better or worse.

So a Newtonian's optics are important but having said that, good mirrors in poor scopes will probably not hold collimation so well when the scope is moved, so the benefit of the good mirror would be forgone to a certain extent.