Cannot see anything

[Zinia]

I cannot see anything through my Celestron Astro 90 .I can only see black and yellow.

[John]

I think you have to give us more to go on than that

- What were you trying to observe ?

- Where are you observing ?

- What eyepiece were you using ?

The above will give us a chance to help with your problem.

 

[iPeace]

Have you tried out your telescope in daylight? If so, did you manage to get the view in focus?

[popeye85]

The fact you are at least seeing a bit of colour means it could probably just be out of focus and/or your finger scope is miss aligned so you are missing your target-like @iPeace suggests- try setting your scope up in daytime ah bs see if we can narrow down the problem from there

[ronin]

Black I can understand (nothing) Yellow is a bit unusual.

First is if you are trying it out on a nearby building/tree/object then that is the first problem. These scopes do not do "near", where near is less then 2 miles and preferably a quarter of a million as in point at the moon as the closest object it is aimed at.

The bits in order should be Main scope, Diagonal, Eyepiece. Nothing else. Say this as they sometimes come with numerous bits and people put all the bits in they can. 7 year olds are good at doing this, mind you his dad did the same. Later bit says the diagonal may be a cause for concern.

If trying it out during the day then find something really distant to aim at  - trees, churches etc. At this time you could do the finder scope to main scope alignment. They do not come aligned, the process is easy but slow. And in the worst case the 2 may not align as the finder may need a little padding added under one end. Bet you thought this was going to be easy.

Just seen the image of the scope, the diagonal has a rounded section, that I think means an erect image prism and some memory says it causes complications. At this time cannot recall what it might be but there is the impression they do not help. Was there a small about 2" tube that caeme with the scope, that would fit in the focuser and then has the option of putting an eyepiece in that - extension tube by name.

Where is Eastchester ? (US ?) If US then maybe search out a club: http://www.go-astronomy.com/astro-clubs-state.php?State=NY

 

[Stormwind]

I don't know what your scope is like, but with mine, there is a screw underneath the focusser. Every now and then I forget that I have tightened it and no amount of moving the controls will make the focusser move and focus... (It's not obvious that it's tightened...)

[JOC]

Stormwind, I was just going to post the same - in the dark I have mistakenly grabbed and adjusted that screw myself and, as you say no amount of turning the focuser knobs will get the system to move the focus once you've done it until you've loosened it up again.  Been there, seen it, done it and washed the T-shirt!