Just bought my first telescope

[donnaF]

I just bought my first telescope. It was a used 4.5" Bushnell that I bought online.
I set it up and it seems to work. I got a really good clear view of the full moon last night.
Then I turned it to Jupiter (I think, I'm pretty new to this) and it showed up as a pretty clear disc except that I could see the cross bars that are inside the telescope in the image. Was it because there was not enough light from the smaller object? Will it be better without the full moon? What can I do to fix this?
Also, the lenses are dirty I guess. When trying to view the planet I could see trash in the view. Is there a way to clean them safely or do I need to buy new ones?
Thanks for any help.

 

[crazyeddie]

I just bought my first telescope. It was a used 4.5" Bushnell that I bought online.
I set it up and it seems to work. I got a really good clear view of the full moon last night.
Then I turned it to Jupiter (I think, I'm pretty new to this) and it showed up as a pretty clear disc except that I could see the cross bars that are inside the telescope in the image. Was it because there was not enough light from the smaller object? Will it be better without the full moon? What can I do to fix this?
Also, the lenses are dirty I guess. When trying to view the planet I could see trash in the view. Is there a way to clean them safely or do I need to buy new ones?
Thanks for any help.

Welcome to Space.Com!

The cross bars (actually called the "secondary mirror spider vanes") should never be visible at the eyepiece, and I can't imagine how you are seeing them, especially if you do not see them when viewing the full moon. Are you referring to the diffraction spikes? These would appear as faint, luminous spikes on four sides of a bright, small objects, and they are caused by light scattered by the spider vanes. Usually they are not bothersome, unless the spider vanes are very thick.

Unless the debris you are seeing in the eyepiece image is caused by dirt on the lens surfaces that can be brushed or blown off, cleaning them is not recommended. If dirt somehow has gotten in between the glass lenses, it can't be gotten rid of without ruining the eyepiece (unless you happen to know an optician who has experience doing that sort of thing). I'd probably buy some new eyepieces, which will probably be better than the ones Bushnell supplies with their telescopes.

 

[MeteorWayne]

AFAIK, the only way to see the supports for the secondary mirror, is if you are Waaaaaaaaaaaaaaaaaaaaay out of focus. Were you able to see craters on the moon? Were you able to see that dark bands on Jupiter and several of the 4 visible moons? If you couldn't then you need to find the correct focus!

 

[donnaF]

Thanks for the info.
It is the cross pieces that I am seeing.
The moon was very crisp and clear with no trash or cross pieces.
The planet was fuzzy; I couldn't get a real clear focus and the cross pieces were there the whole time no matter how I tried to focus.
I think that I do need new lenses. Could that maybe have something to do with it?

 

[jim48]

As the only real, genuine, bonafide, honest-to-God scientist out here, allow me to offer my congratulations! You're going to have a lifetime of fun! I'm still learning my way around the night sky. Let us know if you see any UFOs!

 

[crazyeddie]

Thanks for the info.
It is the cross pieces that I am seeing.
The moon was very crisp and clear with no trash or cross pieces.
The planet was fuzzy; I couldn't get a real clear focus and the cross pieces were there the whole time no matter how I tried to focus.
I think that I do need new lenses. Could that maybe have something to do with it?

It does not make sense that you would see the "cross pieces" while viewing a planet, but NOT see them while viewing the moon. I really can't explain this discrepancy. Are you using different eyepieces, in each case, or is the effect the same no matter which eyepiece you use?

 

[ianke]

Thanks for the info.
It is the cross pieces that I am seeing.
The moon was very crisp and clear with no trash or cross pieces.
The planet was fuzzy; I couldn't get a real clear focus and the cross pieces were there the whole time no matter how I tried to focus.
I think that I do need new lenses. Could that maybe have something to do with it?

Hello donnaF,
I Think that you might be seeing a phenominon called defraction spikes. If they appear to be the same width as the planet then they are difraction spikes, and yes they are caused by the secondary mirror support. To confirm this try looking at a very bright star like Vega (brightest blue white star near zenith (directly overhead)) just after sundown. It should also show defraction spikes only now they are much thinner. This is a property of reflectors that you get with straight vein secondary supports when looking at very bright objects.

As far as focussing is concerned when looking at Jupiter, I try to focus on one of the moons around the planet. Bring that moon to the sharpest focus and you can be sure that you are focussed for the planet. Even though Jupiter is just passed its closest point to us (called opposition) it is still very far for a small instrument. You can expect to see some banding of the clouds on Jupiter, and perhaps the Great Red Spot depending on where it is on the planet at the time that you view. You should be able to make out the 4 Galilean moons as long as they are not behind or in front of the planet.

One other thing to mention when it comes to reflector telescopes is that they need to be collimated at least once in a while for your size telescope. Collimation is the process of aligning the mirrors between the eye and the "column" of light that you are looking at. This will assure you that you are getting the best possible performance that your instrument is capable of.

Good luck, and may you have many happy hours of viewing with your new instrument.

Clear Skies!
ianke