Cant see jupiter

[Manoah]

Hello everyone, i  had an amazing christmas.

i have a 76/700mm newton telescope. It has three eyepieces: 20, 12.5 and 4 i only use 20 and 12.5. I can see the moon really well and sharp, but as soon as i point my telescope at jupiter i don’t see jupiter but i see the miror. How is this posible and how can i see jupiter. When i want to sharpen the view that miror image gets smaller until its a tiny dot. Am i doing things right? Or what could this be?

 

Manoah

[Stu]

9 minutes ago, Manoah said:

Hello everyone, i  had an amazing christmas.

i have a 76/700mm newton telescope. It has three eyepieces: 20, 12.5 and 4 i only use 20 and 12.5. I can see the moon really well and sharp, but as soon as i point my telescope at jupiter i don’t see jupiter but i see the miror. How is this posible and how can i see jupiter. When i want to sharpen the view that miror image gets smaller until its a tiny dot. Am i doing things right? Or what could this be?

 

Manoah

Welcome to the forum Manoah.

The image will be in focus when it is at its smallest and sharpest. If you are seeing the secondary mirror and supports then the image is out of focus.

With a 12.5mm eyepiece you are only getting x56 magnification, so Jupiter will appear very small. You should be able to see the Galilean moons either side of it though, when you are in focus.

You could try the 4mm which would give x175. This is likely too much for the scope to usefully handle but will show Jupiter larger and may show two equatorial bands.

Give it another go and let us know how you get on.

[Manoah]

Thank you i wil try again tomorow night!

[Elp]

If the scope is pointed at the moon and is in sharp focus, you wouldn't have to refocus much (if at all) to see a planet in focus via the same eyepiece, so something else may be amiss. Keep a detailed log in mind of what you're doing next time, the mirror you're seeing, I'm assuming it's the secondary mirror or it's holder (the one angled 45 degrees before the eyepiece), you shouldn't really be able to see this or it's edges if all the optics are aligned as it's a reflective surface, as mentioned above you might be referring to seeing the central spider and vanes at the front open end of the scope which can be visible out of focus.

Edited December 26, 2023 by Elp

[bosun21]

If you are seeing the secondary mirror and the spider then you are definitely out of focus. I get the feeling that you were expecting a large disc and focussed until you got a larger disc. But at only 56x magnification Jupiter will be very small. Focus on the moon and then move the scope to Jupiter without touching the focuser and you will see the proper size of the planet for your given magnification. A 2x barlow lens would help you with the views of Jupiter.

[Carbon Brush]

To get the two objects into perspective.
The moon presents as a circle about half a degree round. 30 arc minutes.
Jupiter presents as a circle about 1/60 the size of the moon. 30 arc seconds.
Yes these numbers do increase/decrease depending on the positions of earth/moon/Jupiter. But as guidelines they are near enough.

A pair of binoculars (often x10 magnification) will show Jupiter as a very tiny disc rather than a point. The (4 largest) moons obiting will be dimmer points of light.
The moons move around from one night to the next.

Look at our moon and try the different eyepieces.
At low magnification (20mm eyepiece) you should see a sharp image. With the other eyepieces you will see a larger image. But is it clear?
If you cannot produce a clear image, then there is little point trying to see Jupiter in detail.

There are various reasons for a poor image.

The most obvious is sky clarity and stability. This varies with time and is weather related. Come back tomorrow🤨
It can also be a man made problem. If looking low over a (well heated) house roof, or past a flue pipe, you won't get stable air.
Do you get sharp views elsewhere in the sky? Wait until the object of interest moves to a different part of the sky.

The second is the state of the telescope. If it is not well collimated, you will obtain acceptable low magnification views.
High magnification looking at stars starts to show problems. But don't worry, these are usually solvable.

The third is the eyepieces.
Often the eyepieces provided with a starter scope leave much to be desired. Particularly those for higher magnification.

You have not said what make of scope you have, or whether it was bought new or used.
Did it come from an astro retailer? He can help.
For example I was once in Rother Valley Optics shop browsing when a customer came in talking about problems getting a good view of Jupiter.
The (reflector) scope had been bought from the shop. The shop owner asked a few questions and quickly established collimation was a possibility.
He told the customer to bring the scope in and he would carry out a while you wait collimation, as well as showing the customer how to do it himself.
Try that with an Amazon purchase!

You might find something useful in this thread...
 

Keep asking the questions and we will do our best to help you.

David.

Edited December 27, 2023 by Carbon Brush