my new telescope

[cammy05]

:confused:hello

ive just brought a celestron astromaster, i have seen the moon perfect through it and i can get stars, the problem is when i see a planet i seem to get a cross in the middle of the lens blocking the whole veiw its very annoying, ive been told the focus might be bad but why can i see the moon so good? has anyone ever had this or no how to correct it???

[keef_uk]

hi cammy welcome to SGL, have you got any other details such as type of scope?

[pvaz]

Do you see a cross of light extending from the planet? Or does the cross block the planet?

If your scope is a Reflector/Newtonian and you see a cross extending from the planet (4 rays of light) but still can see the planet thats the diffraction effect caused by the spider (spider = structure that holds the secondary mirror in place). If that's it then it's normal. You can reduce the effect by baffling the spider vanes with proper paper and using EPs that reduce glare and are well baffled them selfs.

If it's a different matter then I can't help cause it never append to me.

[acharris77]

Hey, if you seeing a cross in the middle of a planet like say mars, then it sounds like you are out of focus, as if you are not in focus then you see the disc shape and a cross in the middle of the spider vanes holding the secondary mirror, it should go when you get focus.

Do you re-focus when you change targets or when you change eyepieces, as you need to do this. Best thing to do is locate a planet and wind the focuser in and out a few times, watching in the eyepiece to see what happens with the image, as you should find as you get to the sweet spot of focusing, the cross will disappear. Dont expect to much from Mars, as the viewing is not the best showing as a bright light.

This should help you get used to your scope and find the sweet spot of focusing it. Hope this helps.

[gregnorth1982]

Hi,

Yeah I agree it sounds like a focus issue. I had a similar problem when I first used a barlow. I could scroll the focus wheel from limit to limit without finding focus, so I moved the barlow out a little, secured it with the locking screws and then I was able to focus. If you aren't using a barlow then I'm stumped I'm afraid.

Hope you get it sorted,

Greg.

[cammy05]

hi i've tried focusing it all the time but the cross is still there, when i look through it in daylight or at the moon its not there, i it is normall with this kind of telescope does anyone recomend a different telescope that hasen;t got this cross?

[Cornelius Varley]

Which model Astromaster is this ?

Peter

[cammy05]

its a astromaster 114

[Cornelius Varley]

As the others have said the cross you are seeing is from the spider vanes supporting the secondary mirror. I am not quite sure why you see them when looking at planets but not when looking at stars. Seeing the spider vanes is usually a focus issue.

Peter

[cammy05]

thanks i know this is gonna sound really silly but which bit is to focus it lol?

[pvaz]

You should have 2 knobs on either side of the focuser (where you put the EP). Turning those knobs moves the EP in or out.

Play with it till the image becomes sharp.

[cammy05]

ok thanks for all your help : )

[phattanglo]

Hey cammy05 when your a newby there are no silly questions.

Just ask away!

[cammy05]

ahh thanks, is there any planets near orion tonight? ive just been out and i saw one but i dont no what it was

[Cornelius Varley]

Download Stellarium from Stellarium and you will be able to identify the planets and stars.

Peter