I am in the process of designing a truss style dob. I plan on purchasing a polished mirror for my first project. I am looking at a mirror that is from obsidian optics. It is a 14" paraboloid mirror. It's thickness seems to be thinner that a lot of others I have looked at. I am interested in opinions concerning obsidian optics (good or bad) and the pro's and cons of a 1.1 to 1.5" thickness for a 14 inch mirror. I have a choice of Plate glass or pyrex. Thanks for the help
Obsidian optics-- forum experience
Started by oilmanmojo, 01/25/2004 07:53AM
Posted 01/25/2004 07:53AM
Opening Post
Posted 01/25/2004 05:51PM
#1
I established a Group over on Yahoo for owners, orderers of Obsidian Optics mirrors. This was done after I won an auction over on eBay for a 16" mirror.
As a guess, you're looking at a similar mirror.
As to thickness: the problem is to get an adequate mirror cell. Since PLOP came along this is not a difficult problem. A standard door plate converts to a 27-point cell for a 16" mirror. (Folded-side triangles are fine. Each point gets a whole 1# force on it.) Don't quite believe models that show super results with 9-point setups.
Pyrex gets the nod. It's easier to work for final polishing, so usually you get better finishing. Better mirrors.
http://groups.yahoo.com/group/obsidian_optics_mirrors/
There have been a few guys whose orders got lost in the mess at Mark's shop and from bad deliveries from his glass suppliers. At present this seems to be straightening out at a rapid pace.
It's no more than three overdue orders now in comparison with several dozen happy campers.
We also recommend a coater and have some tips for construction.
However, be sure to pay with a credit card or other recoverable purchasing medium. If an order falls behind by a year, you need to be able to get a refund. That's not happening now, the long delays, but you never really know dealing with a small business that has long delivery schedules.
Good luck !
As a guess, you're looking at a similar mirror.
As to thickness: the problem is to get an adequate mirror cell. Since PLOP came along this is not a difficult problem. A standard door plate converts to a 27-point cell for a 16" mirror. (Folded-side triangles are fine. Each point gets a whole 1# force on it.) Don't quite believe models that show super results with 9-point setups.
Pyrex gets the nod. It's easier to work for final polishing, so usually you get better finishing. Better mirrors.
http://groups.yahoo.com/group/obsidian_optics_mirrors/
There have been a few guys whose orders got lost in the mess at Mark's shop and from bad deliveries from his glass suppliers. At present this seems to be straightening out at a rapid pace.
It's no more than three overdue orders now in comparison with several dozen happy campers.
We also recommend a coater and have some tips for construction.
However, be sure to pay with a credit card or other recoverable purchasing medium. If an order falls behind by a year, you need to be able to get a refund. That's not happening now, the long delays, but you never really know dealing with a small business that has long delivery schedules.
Good luck !
Funding Member
