Synta Mirror Question

[Rob]

Can anyone tell me what wave & reflectivity the Skywatcher mirrors are?.

Thanks

Rob

[russ]

Main mirror is 1/4 wave and according to a recent conversation with OO, the reflectivitity is 82% (which sounds too low).

[Astro_Baby]

I'm sure I saw one tested that hit 1/8 wave. To get a serious test you'd really need an independent tester really.

[Steve]

I'm sure I saw one tested that hit 1/8 wave. To get a serious test you'd really need an independent tester.

Agreed

Synta/Skywatcher/Celestron don't publish figures.

[johninderby]

About 1/4PV average and approaching 1/5PV for a really good example. Some manufacturers (not SkyWatcher) give it in just wave, not Peak to Valley ( 1/8 Wave = 1/4PV ).

I would expect the SkyWatcher to have about 88% reflectivity when new. The coatings used on Newt mirrors by SkyWatcher and Meade do deteriorate over time, and so it wouldn't be beyond reason for one to have deteriorated to 82% after about 6 or 7 years.

BTW there's some good info here on mirror coatings and testing in general. http://www.opticalmechanics.com/technical_articles/index.html

John

[Astro_Baby]

There was a hellishly long thread on this ages ago - take a look here

http://stargazerslounge.com/equipment-reviews/68085-orion-optics-v-skywatcher-9.html

[russ]

Always best to expect the worse case, you can't be disappointed that way. Seen it mentioned in a few threads on CN that the Synta stuff is ball park 1/4PV but if you are lucky you may get something a bit better. For a mass produced item, i would say 1/4PV is fair to expect.

All i know is i'm happy with the quality of the view all my (bar one lemon) Synta newts have given, that's all i need to know.

[johninderby]

With all the discussion about the quality of various brands of mirrors you shouldn't loose sight of the fact that SkyWatcher makes a really good and consistent mirror that will give you great views.

While I have a 14" OO with a 1/11PV mirror, I also have my little grab'n'go SkyWatcher 200P dob that I enjoy using. While the 200P may not have a premium mirror it's still a very good mirror and I don't think you could better it in a mass produced scope.

John

[Mr Spock]

I can imagine mass produced mirrors having a large variation in quality. For my 250mm I seem to have got a really good one. During the recent Mars apparition I was getting a similar sort of detail to people with 400mm scopes.

I don't see the point, in our average seeing conditions, in spending more.

I will say my 1/8PV (closer to 1/10PV) OMC-140 does produce the cleanest star images I've seen on the very best nights. So maybe if you are into double stars then the scatter free airy disk of this kind of quality would be preferable, but my 250 is the dogs whatsits for planets and a massive improvement on the 200mm Broadhurst Clarkson mirror I had some 30 years ago.