10 Inch Celestron Star Hopper Accessories?

[Joey Bee]

Just bought a 10" dob, (Celestron Star Hopper). And a premium eyepiece (TeleVue Nagler 9mm).

I wanted a barlow to go with this new eyepiece. So the guy at the telescope shop sold me a used Celestron 3x barlow, that is a whopping 5.5" in length.

I tried it with the eyepiece and it won't even come close to being in focus. I mostly see only the support brackets supporting the secondary inside the scope. Ahghugh!!! I guess I need to take another two hour drive to San Francisco to get this sorted out.

Does anyone know the best barlow for what I am trying to do? Would like a 3x but will settle for a 2x. And I am wondering about the quality of the barlow matching the quality of the TeleVue Nagler, I certainly do not want to diminish sharpness, etc. with the barlow, which by the way, the guy at the shop seems to think that pretty much any barlow will do, i.e. will not diminish quality. Is he out to lunch or what?

[admin]

i would think hes out to lunch

any barlow will diminish the resolutionsome of top line barlows like the celestron ultima and antares elite keep this to minimun

the powermates are rated the best in this respecti use the 2X ultima, one other i recommend which i have is the 2.8X Klee-if you figure the $79, that's as good as it gets in this price range, dont forget though

you pushing that fast scope over 400Xyou wont get good focus except only on the best nights of clear and steady seeing

[Johnmore]

All 3x Barlow's are fairly long.

I'm presuming your Televue 9mm EP is type 6, with just the 9mm EP in your focuser the magnification is 141x, then multiply that by 3x for the Barlow and you get 423x magnification.

Max advertised magnification for your scope is 600x,so you are below the max magnification for your scope.

Personally I would email Televue and Celestron and explain your problem.

Also I presume you racked the focuser all the way out and all the way in trying to get it to focus.

Hope some of this helped.

Oh almost forgot Televue has a EP calculator, below is the link.

I can rarely get over 300x and have decent viewing.

Also I don't know what part of the US you are in, but my air here in Ohio is quite unsteady and won't clear till fall more than likely.

Ok I see your 2 hrs from San Francisco.

David

[Joey Bee]

Thanks a bunch for your responses. I finally decided to go for the new Klee, as described on the lower half of this page [Registered users can see links. ] Will come back and post some of the impressions after it arrives. Will be using it pretty much for just lunar observations with a 10" dob and a 10mm televue. This should get me up to 280x, under a relatively clear sky as we have here on most nights (Lake County, Northern California.)

By the way, I Can't wait for Mars and Saturn to come back into the night sky, but I guess this won't be 'til next spring or so.

[admin]

I know for my 10" dob the 3xbarlow doesn't work. However the 3x shorty barlow is designed for relectors. Fortunately that's what the dealer told me, so that's what I got. Shorty werks great.

[admin]

Be patient for Mars, not as large late next year 2007 Dec 18th... tho 15.9 seconds diameter, large enough for some major details even in modest scopes...

Start viewing prior as well as after Maximum, example last observation on Mars the SPC Southern Polar Cap visible few months prior to Max size, and lost due to the Martian Summer......

Was able to identify the largest feature Syrtis Major down to 9.5 Seconds Diameter in the XT8, better at plus 12.....

Frequent observation used was 250X with the XT8, the 10 inch Dob might be perhaps 300X, but skys will determine the allowed max powers....

Last weather is unpredictable, and best views may occur for a given area before and after maximum, rare are the Steady Skys, lots of viewing is eventually rewarded with nice details....

Detailed info on Mars:

THE 2007 APHELIC APPARITION OF MARS

[dantistryfiliya]

Try 32 or 26 mm eyepiece with 3X and see what happened. If it work then you use too high power and that's the problem!

I am not sure that Nagler is 82 degrees might not too well with barlow. I use up to 200 power most of the time! High power reduce the light, object move too fast and easily shaking!

By the way that I am glad that you got a nice 10" dobsonian and do you add some weightat the bottom of your telescope? Because your Tele Vue Nagler with 3x barlow is pretty heavy!

[admin]

XT8 With good skys, Planets tend to be bright so can take powers to the maximum, very impotant for serious Martian observing... Do group viewings w/250X, needs correct placement so planet goes across the entire field of view, 200X is about minimum to see Martian details, need max for this tiny disc, have done 400X with best conditions but skys rarely allow... If you have trouble w/high powers, use lowest power eyepiece but leave things in-focus at highest power, if object is lost, simply switch to the lower eyepiece, center, and back to high power..you don't touch the scope during high power viewing until it move off the field....