SC scope with a Powermate

[alan potts]

This has been on my mind a while. I would like thoughts on this please.

The SC Meade was the first scope I bought when getting back into Astronomy about 6 years ago.

It is not a cheap scope but it is by no means the most expensive on the market. I don't think it ever really lived up to the marketing for me, in fact I would go as far as saying they are over priced.

Still I am not going to throw it away and would never be able to sell it here. I have never been happy with the star disc that you get with these, even at lowest magnification on bright stars. I would use, lets say X74 using a 41mm eyepiece. the star image never appears the same as it does in either the 115mm refractor or the M/N 190m on a very similar power, within X5. Things are just not as tight and there is nothing wrong with the collimation, it's always been like this.

I ask this: a Powermate doubles the F/L of the scope, would this have an effect on tightening the star image. Would I get the same view using a 20mm Nagler which gives X152 and a Powermated 41mm Pan giving almost exactly the same power. I fully understand the FOV is different but I am just talking about the centre, would a bright star, say Sirius appear the same.

This is the only scope I have where I have not seen the Pup star.

Is it possible to say or is the fact that they are two different eyepieces making it impossible to formulate an opinon.

Or is the answer, you have the gear try it.

Alan.

[michael.h.f.wilkinson]

I think not, as you are looking at the diffraction pattern (plus possible aberrations) of the scope itself. Nothing can correct the former, and the latter could only be corrected with a matched piece of optics (which the powermate is not). I must say my C8 give pretty decent star images, though the APM 80mm is tighter at the same exit pupil. At high mag (above 140-ish) the C8 is tighter, as you would expect given 2.5x wider aperture.

I gather there is a lot of variation in correction of spherical aberration in SCTs, and I might have a good one.

[alan potts]

Michael,

Thanks for your thought on that, I guess what you say is logical when you think about it.

I find the refractor is better than the Meade at the same type of magnification but it cost almost the same so it has every right to be.

I think I made a mistake with the scope in the first place, well for me anyway. I am thinking of getting a 180mm Mac from SW. What I don't understand is it has never shown me Sirius A&B sommething that this year I have found easy in smaller appertures, these things are sent to try us.

Clear skies,

alan.

[michael.h.f.wilkinson]

I assume you are talking about the 12" LX200. Odd that that cannot spot the pup when I managed with my C8 (difficult, but then it is lower in the sky for me). I am not sure a Skymax 180 will be a step up from your MN190, however. A C11 or even C9.25 might be better.

[alan potts]

Michael,

I don't believe it is a step up either, I just want it because it is very good on doubles and planets, the LX is going in an observatory soon anyway I will have room for another scope in there too, when I build it. I have had the base down for almost 3 years, still it hasn't moved so I must have done a reasonable job. All my other scopes are gab and go's and I just take them out when I want, the 12 inch I now have to be up to moving it. When I bought it and was building the house I could almost carry it with one hand, now it's more of a task.

I just don't understand the Pup with this scope, I have tried it hundreds of times over 6 years from a better latitude to yourself and never seen it once, I have given up now. Saying that it will be clear to-night so I might just put the scope outside.

There is no way I would buy another SC scope, when you think the M/N is less than a quarter of the price albeit without a mount and for me it's a much better visual instrument. Shame I don't have the mount to use it as a AP scope, it is really meant to shine then.

Thanks again,

Alan.