I hate to tell you this but your 8" scope has a spherical mirror and not parabolic. This is not mentioned on ebay. This is how you got an 8" scope for less then 300. Also please note the fact that the center of your scope is losing alot of gathering power because the diaganol is so huge!.

You will have to replace your mirror with a parabolic 8" mirror. maybe you can find one on ebay.

http://www.opticalvision.co.uk/20.html

This is the company that imports the scope, I did not buy it on ebay.

Andy

I know for a fact that the chinese supplier (LEE&KAO) does make the exact same scope with a spherical mirror. Ask someone how to test the primary mirror. I have a sample of the spherical mirror and it has the exact same problem you described. It is entirely possible that a spherical mirror may have been sent to you (or to optical vision) by accident instead of the parabolic version.

good luck!
Pete

Since I first posted this thread I have been out several more times with this scope, I collimated the scope as advised by other members and star images out of focus now look like they do in the collimation instructions(to me anyway, when i first checked with the instructions it appeared to be way out!!) I also bought some new eyepeices as i was told the helios ones are not much good, i bought a couple of meade 4000 series ones, then last i took the scope out for a couple of hours before i used it, the first time i used it after all the above I could see about 100% better by comparison, the star imagaes seemed to be very clear and i could see plenty of banding etc on the planets with no purple edges etc.
Regarding the mirror , is there any way I can check whether I have been sold a spherical mirror and not a parabolic.

Regards
Andy
Ps: anyone else know....

Andy, Optical Vision Ltd is a pretty well known & reputable supplier in the UK. Their ad clearly states that the mirror supplied in your scope is parabolic. I'd be very surprised if the co had 'mis-advertised' their product, as they would be fully aware of the legal consequences under the Trades Description Act of so doing!


I'd be tempted to send an e-mail about your concerns to see what response you get. If you're a member of a local astronomy club (or have one near to where you live), perhaps someone there would be prepared to help you out with any testing.

I'd certainly e-mail OVL - they have a legal responsibility to ensure that you received the goods with the exact specifications that they advertised.

Keep us updated on progress!

Pete3000 - just to say welcome to Spacetalk!
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If you can see banding on Jupiter and the rings of Saturn, in my opinion, you have a parabolic mirror. A spherical mirror that fast is only good for low power viewing of faint fuzzies, and I don't think it could render a clear enough image of Jupiter to show any banding.


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i have also just bought a Helios 200, In ALL the advertising from suppliers (Optical Vision, Warehouse Express, Sherwoods in birmingham, Stockport binocular and telescope, etc) the spec describes a parabolic mirror. Also, the scope doens not cost less that £300 as someone had described, it costs £450.

The Explorer range of scopes change to parabolics in the Explorer 130P and scope with a higher spec. Now I have seen moon transits, the GRS, several cloud bands, the Cassini division, bands on saturn etc with the EXPLORER 130P, although I havn't really tested my 200 out yet, I'm fairly certain I'll get even better results.

On the subject of eyepieces, the Helios supplied pieces are Plossls which I have heard are better than the eyepieces supplied with comparable Orion Optics scopes.

If the manufacturer of the Helios scope is Lee&Kao (as the vendor you bought it from), then I have been told by Lee&Kao that they sell spherical and parabolic mirrors with their 200mm scopes. I just hope that with the original question in mind, that somehow a spherical mirror was accidentaly sent in that scope instead of a parabolic.

be leary of the term "Concave mirrors" I have seen that in some other adds.

Can anyone send me a photo from the 8" scope with the highest power of jupiter or saturn?

thanks!
Pete

Well if the mirror is not parabo0lic as described in the spec then they are breaking the law and I presume something would have been done about it by now?

Can't send a picture but I can describe the view.
Only had my 200 out briefly so it hadn't cooled fully and seeing was poor. Despite this, throught the turbulance I saw detail within the equatorial bands on Jupiter and detail around the poles. On Saturn the Cassini ring is clear as a bell with cloud detail at the equator and poles.
M42 displayed whispy detail within the cloud. Trapezium easily viewed. And this was in moments when the air was just still enough to catch a glimpse.

Chris

Oh, one more thing, I've just made a rough measurement of the diagonal secondary mirror and seen end on it is just over 1 1/2 incches in diameter. Is this particularly large?

Chris