view through eye piece

[corgireg]

Hi, I have just bought my first telescope a Celestron Astromaster 114EQ telescope, I don't know if it is working correctly or not as this is my first. When I focus in on, say the Moon, its good and clear, but when I focus on a more distant object I can see the struts and centre piece of the small mirror in my view, is this correct or is it faulty

[Ricochet]

The focus points of the moon and all of the stars and planets are practically identical. If you focus on the moon and then move to a star it will also be in focus. If you focus on the moon and find that stars are not in focus at the same point then you have not focused on the moon. 

As a rule when focusing on astronomy you should always turn the focuser so that the image becomes smaller. Stars will always be point sources and planets will be small disks or crescents. 

[Owmuchonomy]

If you can see the vanes holding your secondary mirror then you are miles away from focus. As above focus until a star becomes as small as possible. You then don’t need to adjust it unless it is slipping or you change eyepiece.

[Waddensky]

If your focus on the Moon is sharp, you should easily be able to see craters on the terminator (the division between the illuminated and dark side of the Moon). Can you describe what you see when you focus on the Moon through your scope? As Ricochet said, the focus points for celestial objects are identical, you don't need to refocus once you're in focus.

[John]

Assuming that you keep the same eyepiece in the scope, if you have the moon in sharp focus, you would only need to make a very small adjustment to get sharp focus on something further away such as a planet or star.

 

 

[corgireg]

17 hours ago, Owmuchonomy said:

If you can see the vanes holding your secondary mirror then you are miles away from focus. As above focus until a star becomes as small as possible. You then don’t need to adjust it unless it is slipping or you change eyepiece.

what I am trying to do is, when I look at the moon its in good focus and very clear, but when I look up further at Venus which is a very bright small dot and I try to bring it closer by using the focus wheels on the eye piece, that's when I can see a black disc and struts 

[corgireg]

16 hours ago, John said:

Assuming that you keep the same eyepiece in the scope, if you have the moon in sharp focus, you would only need to make a very small adjustment to get sharp focus on something further away such as a planet or star.

 

 

what I am trying to do is, when I look at the moon its in good focus and very clear, but when I look up further at Venus which is a very bright small dot and I try to bring it closer by using the focus wheels on the eye piece, that's when I can see a black disc and struts 

[corgireg]

17 hours ago, Ricochet said:

The focus points of the moon and all of the stars and planets are practically identical. If you focus on the moon and then move to a star it will also be in focus. If you focus on the moon and find that stars are not in focus at the same point then you have not focused on the moon. 

As a rule when focusing on astronomy you should always turn the focuser so that the image becomes smaller. Stars will always be point sources and planets will be small disks or crescents. 

what I am trying to do is, when I look at the moon its in good focus and very clear, but when I look up further at Venus which is a very bright small dot and I try to bring it closer by using the focus wheels on the eye piece, that's when I can see a black disc and struts 

[Waddensky]

6 minutes ago, corgireg said:

what I am trying to do is, when I look at the moon its in good focus and very clear, but when I look up further at Venus which is a very bright small dot and I try to bring it closer by using the focus wheels on the eye piece, that's when I can see a black disc and struts 

Thanks! Sounds like your focus is spot on, Venus should look like a small dot in your telescope. What you're trying to do, is getting Venus closer by using the focus wheels. That's not possible. If you want to see Venus larger, you'll need to use another eyepiece with a shorter focal length, or perhaps a zoom eyepiece. What kind of eyepieces were delivered with this scope?

[Ricochet]

1 hour ago, Waddensky said:

Thanks! Sounds like your focus is spot on, Venus should look like a small dot in your telescope. What you're trying to do, is getting Venus closer by using the focus wheels. That's not possible. If you want to see Venus larger, you'll need to use another eyepiece with a shorter focal length, or perhaps a zoom eyepiece. What kind of eyepieces were delivered with this scope?

This. The focuser is just for focusing, not for changing magnification. Magnification is set for each telescope/eyepiece combination and can be found by dividing the focal length of the telescope by the focal length of the eyepiece. For instance your telescope has a focal length of 1000mm and is supplied with 10 and 20mm eyepieces. This means that your 10mm will give a magnification of 100x and your 20mm will give 50x. For planetary observation 100x (10mm) will be the better choice of the two. 

[corgireg]

3 hours ago, Waddensky said:

Thanks! Sounds like your focus is spot on, Venus should look like a small dot in your telescope. What you're trying to do, is getting Venus closer by using the focus wheels. That's not possible. If you want to see Venus larger, you'll need to use another eyepiece with a shorter focal length, or perhaps a zoom eyepiece. What kind of eyepieces were delivered with this scope?

The eyepieces I have are a 10mm and a 20mm, what do you suggest if I want to see planets closer up

[John]

You will need to either use a shorter focal length eyepiece such as a 5mm or use a 2x barlow lens with the 10mm eyepiece which effectively makes it a 5mm.

The planets do tend to look small with telescopes though even when very high magnifications are used.

 

 

[corgireg]

25 minutes ago, John said:

You will need to either use a shorter focal length eyepiece such as a 5mm or use a 2x barlow lens with the 10mm eyepiece which effectively makes it a 5mm.

The planets do tend to look small with telescopes though even when very high magnifications are used.

 

 

Thanks John this information is very useful

[Waddensky]

35 minutes ago, corgireg said:

The eyepieces I have are a 10mm and a 20mm, what do you suggest if I want to see planets closer up

John above has some great advice. Your 10mm eyepiece will give you the largest magnification available with your current equipment (100x). A 5mm eyepiece will result in 200x magnification (just divide the focal length of your telescope - 1000mm according to the Celestron specs - by the focal length of the eyepiece to calculate the magnification). A 2x barlow will produce the same result with your 10mm eyepiece.

Keep in mind that planets will always be small at any useful magnifications, and that the maximum available/usable magnification depends both on your telescope and the stability of the atmosphere. For planetary observing I rarely go over 150/200x.