GSO 12" Dob - problem

[NorthernLight]

Good Morning Everybody,

I recently bought a GSO 12" Dob and have some start issues that I hope you may have an answer for:


9x50 finder scope brings only blurry images - can this be focused?
no focus achievable when using 1.25" 2xBarlow and EP`s shorter than 15mm - but 5xPowermate and 25mm works great
imagages (visual) appear yellowish
2" GSO 30mm EP very blurry closer to edges
Thanks in advance!

Cheers

[astro_nutt]

Hi Max.
Firstly, congrats on your new scope and don't believe the myth about it bringing on the rainclouds!
1. The finderscope should be adjustable. The front lens cell is threaded to the tube and is held there by a locking ring behind the lens cell. Gently undo the locking ring and then turn the lens cell either in or out to focus. Try it on a bright star.
2. If your 2x barlow is of the long tube type, it would not allow the focuser to do it's job. I use a short tube barlow with no problems.
3. Hmmmmm. Stray light source entering/relfecting off the tube/focuser, skyglow.
4. I had one of these and it did the same thing. Just enjoy the view of the inner half of the image.
Cheers!

[Waxing_Gibbous]

Pretty much what AN said except bin the findersope - it's hopeless. Replaced mine with a Vixen red dot finder and never looked back.
'Scope!
Peter

[JethroB76]

If you are running out of out-focus with your barlow you can pull the barlow out just a bit before tightening the focuser.
The GSO model focusers will often give you a little more travel if you loosen the screw on the unuderside of the focuser too.

[NorthernLight]

Thanks guys, appreciate your quick and knowledgable answers. Only one thing appears to be true after all: as soon as I purchased - the clouds rolled in and it looks like they`re gonna stay for a while....

But since I have you here:
how would you best adjust the height of the scope in the cradle. It has adjustable studs on either side and I tried my best to reach an equilibrium state with my most commonly used eyepiece. However, the balancing point changes with the angle at wich I point the scope towards the sky - a point closer to the horizon and the scope stays still, another point closer to zenith and it tends to move. Even with fully tightened clutches the effect remains and makes higher power planetary work rather painful.
Any suggestion how to overcome this self-movement?