Is the problem collimation? Or should I get a different telescope?

[rayman888]

Hello I'm a nemby.

I have just bought a Celestron powerseeker 127mm x 1000mm newton, short tube and rack-and-pinion eye-piece mechanism..

Out of the box terrestrial images looks blurry at around 500m and double images (vertically) at around 3000km with the smallest magnification, 20mm eye piece. Images doesn't focus properly. The moon didn't look as sharp as a 50mm refractor but I can still see the craters. I can see Jupiter and its of its moon but the bands are just barely imagined with the highest magnification, 4 mm EP. Is thre somthing wrong with my collimation? The spider holding the secondary mirror is not centred. The arms are not equal length physically. Is there a physical fault with this telescope?

Should I just return this telescope and get a GSO/Bintel 8" dob? The Bintel is now $599 (new mount, pricing and stock). I would like to see DSO and maybe later consider photography. I have a heavy Samsung DSLR GX-10 and a Canon point-and-shoot digital powershot 710. Is the dob good for photography compared to a EQ mount in terms of tracking for photography and long exposure?

Dob website:

http://www.andrewscom.com.au/site-section-10.htm

http://www.bintel.com.au/Binscope.html

Can anyone also advise whether an Andrews Maksutov-Cassegrain 6" OTA(150x1900) for $499 with either a EQ3C ($199) or EQ5C dual axis motor drive kit($199) might be a better option?

I'm aslo considering an EQ mount 6" newton. I have 2 in mind.

A Bintel 6" BT150EQ Deluxe 100mm x 750mm ($499) or a GSO 6" GS-500 SDX with crayford style microfocuser with 10:1 focusing and 4 plossl eyepieces for $599. ATM a Bintel 8" BT200EQ newton with EQ mount is $695.

Can anyone help.

Thanks.

Edit: due to pricing changes.

[bojan]

I think you answered the question yourself.
Telescope is most probably out of collimation.
Another way to check is to remove the eyepiece and look down the tube.. you should be able to see your own eye centered (including everything else) .
If not, you should try to collimate it.

[rayman888]

Thanks.

That's what I think, that the secondary mirror is not aligned. However does the centering of the secondary mirror depends on having the length of the arms of the spider EXACTLY EQUAL or can the secondary mirror still be aligned by collimation regardless?

When I properly collimate this Celestron Newt would the double/blurry images disappear when I view terrestrial object? IE as a means of testing the collimation prior to using it again at nighttime.

The pricing is very competitive even when compared with Andrews', unless its a fake, which I doubt.

Thanks again.

[bojan]

The secondary actually does not have to be dead-centre, it is supposed to be offset by couple of mm away from eyepiece (to minimize vignetting).

Would blurry image go away, I can not tell you for certain, but if the main mirror was not collimated, after you are done with it, you will have much much better result (unless mirror is plastic.. but I doubt it :-) )
Check this forum (and web) for collimation procedures, there were plenty of discussions in the past on this subject.
Rough collimation can be done with your eye only (an old black plastic box for film container is great help - you should drill the small hole in the bottom centre, and then insert it instead of eyepiece and look through that hole down the tube.. you have to end up with everything in centre, except secondary which has to be offset by 2-3mm AWAY from eyepiece).

Also, make sure the main mirror is not tightened too hard in its cell... the clips should just be touching the mirror, but there should be NO PRESSURE applied to it. Glass is surprisingly elastic and can very easily be deformed :-)
Good luck..

[rayman888]

So does anyone think I should just pull the plug and get a more expensive telescope around the $500 mark? See below for the ones I'm considering.

[Starkler]

Definitely sounds like the ubiquitous Jones-Bird scope. These scopes are lemons (search this site for details) and if you can return it, you definitely should.



I say yes, and forget about photography unless you can muster up 2k minimum for a scope on a decent mount.

[rayman888]

Quick question.

Will an 8" dob allow me to see DSO like gallaxies, nebula etc? You know, the spirals etc rather than small blobs/spots of light. In terms of tracking will the dob track just as well as an EQ mount?

Thanks.

[Merlin66]

A 200mm will show a lot of fuzzies, but a 250mm dobbie is even better!!
Not much good for photography, but great for visual and finding your way around the sky. Plenty of objects to be seen and admired!!!
Unfortunately to get half decent photographs you have to make the investment of a good equatorial mount ( Skywatcher HEQ5pro, or similar) then you need the camera/ imaging gear and the adaptors and the software and.....

[andrewk_82]

Hi Ray,

I'm only a newbie too, but I write this from my recent experience and also from the advice of others in this forum. I started using my 10" scope with sky high expectations, but have since re-adjusted these.

If you are expecting to easily see galaxy spiral arms from your home in Sydney even with a 250mm dob, then you will most likely be dissapointed.
I live in a rural area where in town the skies are reasonably dark (I can see the milky way and SMC, LMC easily from my front yard), but even with my 250mm dob most galaxy spiral arms cannot be seen, and when they can be seen they are faint to say the least, just visible with averted vision.

On the other hand globular clusters are quite good and well resolved, even with a relatively bright moon in the sky. So the brighter clusters may be seen reasonably well from your home.

Also nebula do show up a lot better than galaxies (m42 looks awesome as do many others) and no doubt this will be helped when my UHC filter arrives. These also would be a lot better from a darker site.

For galaxies you need really dark skies as some members on this forum have reported from really dark sites much more success with 6" scopes than I have had with my 10" dob (which I am hoping to get to a dark site soon if the weather clears up).

As many on this forum have said the more you practice the more you will see, and even in my short experience this is true. Just don't expect to get your 8" or 10" scope and expect to see photograph like images through it.

I hope this helps.

Cheers