skyliner 250PX

[stargazer1981]

I've just purchased this skywatcher10 inch dob. Can someone help me as I can't see anything through it at night. I have the standard eyepieces and a 40mm bresser coupled with a revalation 2x Barlow. The secondary looks aligned but waiting for a collimator to check alignment. What am I doing wrong guys?? Please help

[Paul M]

First question:

What have you been looking at?

Can you see things in focus during the day, a distant building for example?

Collimation is quite technical and unless you are sure about it may not be very helpful.

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[Dude_with_the_tube]

for starters use the 25mm supplied eye piece as 40mm is too low magnification.

Ensure the big plastic dust cup has been removed

dont worry about collimation of your scope, even poorly colimated  still should come into focus.You should have a 2" adapter and also a 2" to 1.25" adapter. Put both into your focuser (2" adapter first,followed by 2-1.25")and then put the 25mm plossl into the 2" to 1.25" adapter.Rack the focuser fully in and then point it to any star you can find and slowly start racking the focuser out.At some point you should reach the focus and the star will become sharp.Hope that helps.Also i hope you have alligned your finder with your scope to ease the finding? 

[russ.will]

The usual issue with SW Dobs, is that the standard focuser is too short on it's own for visual use. Normally, it comes supplied with a 2" extension tube and a 1.25" extension tube. Basically, if you have and are expecting to just use a 2"-1.25" adapter in the focuser as you may well have done in previous scopes, you will need to use the 2" extension tube to extend the focuser barrel to achieve focus.

It should also be said that the supplied items are pretty basic and as they lack brass compression rings, will mark the barrel of anything you put in them. Altair Astro make some nice self centering alternatives for not a lot of money.

That's my best guess based on the information you have supplied. If you could post a phone photo of the EP in the focuser, that would be really helpful.

Russell

[itmo]

take eyepieces off the telescope and just point it towards the sky at night or a far away object and look in the focuser. do you see stuff? take an eyepiece in your hand and move it back and forth to find a focus if the focuser doesnt move far enough. wait until the moon is up and point the telescope at the moon , then look in the focuser without eyepiece and check if you see the moon? center it and add an eyepiece , try to focus. etc.  Look in the focuser, does the secondary look roundish? is it straightish? if you look from the middle can you see most of the primary mirror? Have you used telescopes before? did you put the eyepiece in the correct way (metal bit goes into the focuser) are there any bent parts? 

[Paul73]

If it it is the Flexitube version, make sure that it is fully extended. It has two stop positions! I couldn't see a thing through mine until I realised this.

If yours is a solid tube, this advice will be entirely useless.

Might be worth posting a picture of the scope as you have it set up. One of the eagle eyed collective will put you right.

Good luck.

Paul