PV Optics

[vlebo]

Looking (again) at OO UK VX dobs , I am wondering if the PV optics upgrade from 1/6 to1/8 or 1/10 are worth the extra outlay. Is 1/6 better than the optics you get from say , a Skywatcher Flextube. Would 1/6 PV be adequate from my light polluted Stanmore back garden or do the upgrades make enough difference to be justifiable ?

Thanks in advance

Vlebo

[Mike73]

There was a good discussion about this recently

[crashtestdummy]

Most commercial dobs like the skywatcher are 1/4pv commonly known as diffraction limited.if your only ever going to use the scope in a light polluted sky you wont notice the difference between 1/4 pv and 1/10 tbh.

[cs1cjc]

...if your only ever going to use the scope in a light polluted sky you wont notice the difference between 1/4 pv and 1/10 tbh.

I do not think this is true. You need good optics to view well at high power so particularly for the moon and planets, which are largely unaffected by light pollution

[Scooot]

My mirrors 1/10, I am very pleased with the views. I doubt I could normally tell the difference if it were 1/8 or 1/6 as I have to deal with light pollution as well. I took the view that as I'd get a certificate with the zygo test I'd have no doubt I'd definitely have a good mirror, whereas with other scopes it might be a bit hit and miss. So I paid up for the difference on the basis that it was a long term investment and over the years It would be worth it. Hope this helps

[Scooot]

I do not think this is true. You need good optics to view well at high power so particularly for the moon and planets, which are largely unaffected by light pollution

This may well be true I get fantastic views of Jupiter and Saturn when they're in reasonably placed in the sky

[crashtestdummy]

There's a link in one of the other threads thats show that most people cant tell the difference,and that the more precise wave mirrors only really come into their own from a dark site

[estwing]

There was a good discussion about this recently http://stargazerslou...59-mirror-wave/

plenty of info Here...

[Scooot]

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There's a link in one of the other threads thats show that most people cant tell the difference,and that the more precise wave mirrors only really come into their own from a dark site

yep but my point really was that I can be sure I have a good mirror and at say an extra £100 it works out at only £20 per year over 5 years, I'm sure I'll still be using the scope then.

[crashtestdummy]

Some people wont want to pay the extra money though and thats more what the op asked

If not too much extra i would pay for the 1/10 pv but in general its not actually a good value option for anything other than piece of mind

[Scooot]

Some people wont want to pay the extra money though and thats more what the op asked

If not too much extra i would pay for the 1/10 pv but in general its not actually a good value option for anything other than piece of mind

Agreed

[John]

Orion Optics mirrors also have the Hilux coatings. I don't fully buy their claims about how much more reflective it is over other coatings, although I think there is some difference, but it does seem to have a longer life than standard coatings. When I moved down from a 12" Meade Lightbridge to a 10" Orion Optics with 1/6th wave PV primary and Hilux coated mirrors I can't say I really noticed the drop in aperture that much.

My feeling is that better quality optics (this goes for all scope types) should be able deliver benefits when it comes to high contrast, high resolution observing such as the planets. If the conditions allow and if the scope is well collimated (important points !) better quality optics should support higher magnifications without image degradation and improved contrast because more of the light is being focused there you want it to be (hence the higher Strehl rating).

I'm thinking here of the very high magnifications that Shane (Moonshane) uses with his dobs with great results according to his reports

[vlebo]

Interesting points. I suppose it boils down to paying the extra and knowing you have as many points in your favour to aid in getting those views that come when all the other factors fall into place.

[crashtestdummy]

its basically like having the same car on a race track as sebastian vettel.you know your car isnt the limiting factor so its one less think to worry about

[vlebo]

Sorry , looks like this was discussed in some depth recently here http://stargazerslounge.com/topic/174659-mirror-wave/

I will give it a read later this morning