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I can't see Jupiter


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I have a Celestron Astromaster 90. Last night, I went to go see Jupiter, and with the 10mm eyepiece and the *angle lens?* (not sure if that's what it's called, but it's the thing that lets you look through the telescope from any direction other than straight through, mine is at a 90 degree angle) I got a decent image, although I don't have a Barlow, but I was able to discern the larger cloud bands and four moons, but the focuser was almost all the way out. When I took the thing* out, I was unable to focus on Jupiter at all. I could hardly see the moons and Jupiter was a massive white blob. I am an amateur and have no idea what's going on. If anyone knows what's going on and/or how to fix it, I would greatly appreciate it. Thanks!

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Hi Gabe

Every scope has a range of focus (the distance from the front of the scope to the eyepiece)  dictated by the in and out movement of the focuser.

In your case the focuser is nearly all the way out with the THING (a diagonal) attached.

If you remove the THING then you've removed a chunk from that distance, the eyepiece is now much closer to the front of the scope.

To get focus back you have to move the focuser that chunk further out, to place the eyepiece back where it was in distance from the front, which you can't do.

So basically you don't remove the diagonal.

Michael

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Hey, I second What Micheal said. 

The same thing happens with my 8" Dobsonian. In order to focus my 2" eyepiece, GSO has included an extension along with my scope. Without extending, stuff appears like blobs. So what I would suggest is, instead of adding a diagonal in between (more opticals = less quality), do not fully insert the eyepiece in the focuser barrel. Experiment with the distance. It should work. Let me know.

Regards,

Prabal

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Hi @Gabe and welcome to SGL. :hello2:

Depending on where you are, Jupiter for us amatuer astronomers in the mid-northern latitudes and above, Jupiter, (and the other planets), is low down at the time of writing. 

The supplied eyepieces and some accessories that come supplied with high street department store telescopes may not be of the best quality. If you can visit a local astro society/club, find out when they are having a star-party and take along your 'scope, etc., and see if things are any better.

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I seem to be having a focusing problem with my 6" Schmidt/Cass.  I've viewed Saturn and Jupiter before with beautiful images but now it's as if the planet is huge with a big black circle in the center.  Kind of an extreme image of what you want to collumate.  I f I remove the eyepiece and look into the diagonal I see the same thing but I can look from the side and see what I think is the acutal planet behind the black circle.  The black circle is in the middle so I don't think I have a collumation issue.  I can start to make the ring of light around the black circle smaller by focussing closer but I get to the stopping point.  Backing the focus know all the way to infinity (I'm too scared to go all the way back for fear the knob will come all the way off) does not help and makes the ring of light bigger.  I'm inclined to believe the device may have been jostled and the focal point has somehow shifted but I'm hoping you guys have seen this before and it's just some rookie mistake.  Any advice would be greatly appreciated.  Jupiter is as close as it's gonna be for awhile and I sure would like to see it!

 
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@Pollyanna24 it sounds like you are just not reaching focus. Have you changed anything in your setup? Diagonal or different eyepiece? SCTs have a pretty big focus range because they work by moving the primary so its unusual to run out of focus range.

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No changes.  I'm using a 32MM eyepiece and I've switched to 25 and 17 rule out a problem there.  Thanks so much for your reply though, Supernova!  I'm happy to know my troubleshooting skills are intact as I have reached the same conclusion.  I may have to visit the next star party with the local astronomy group and get a pro involved.  I know I haven't shocked the telescope badly.  Just a couple of trips in the car, well padded and secure.  I'll give it another go tonight to see if I can figure anything out.  Thanks again.

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 I can't think that you have done anything serious to the scope. Worst case it would just go out of collimation but would still go through focus. It sounds like yours just won't come to focus. I'm sure it will be simple to resolve once you've figured it out. Sorry not to be more help. You could just post up a picture of the setup as that may allow us to help a bit more.

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Gabe

Have you tried using any other eyepieces

With my 10" Dob, have issues viewing Saturn and Jupiter with 10mm eyepiece

When use 17mm, even 25mm 

You using 1.25" or 2" eyepieces

I found also was not able to focus using 2" barlow, and not an issue with 1.25" barlow

John

 

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22 hours ago, cletrac1922 said:

Gabe

Have you tried using any other eyepieces

With my 10" Dob, have issues viewing Saturn and Jupiter with 10mm eyepiece

When use 17mm, even 25mm 

You using 1.25" or 2" eyepieces

I found also was not able to focus using 2" barlow, and not an issue with 1.25" barlow

John

 

I have 1.25" eye pieces. I only currently have two eye pieces, one is the 10mm, the other is a 20mm. I am relatively sure that I would have tried that eyepiece but I can't remember. I'll try that when the sky decides to clear.

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Hey, I wanted to say thanks too all the people who have helped so far. I would also like to thank michael8554 for telling me that the THING is called a diagonal 😆 

 

I was wondering, if I got a Barlow lens, would that help my problem? 

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On 09/06/2019 at 16:58, Pollyanna24 said:

Backing the focus know all the way to infinity (I'm too scared to go all the way back for fear the knob will come all the way off) does not help and makes the ring of light bigger. 

Turn the focuser knob one way until it will not turn any more. Now turn it the other way and count how many turns it takes for you to reach the point where you reach the point where the knob will not turn. With a 6SE (I assume this is your scope)  this should be in the region of 30 turns. If you have about 30 turns then you have the full range of travel, if you have fewer then there is some internal issue that needs repairing.

If you have the full range of the focuser then try aiming it at terrestrial targets at varying distances and see if any of them are in focus. Once you find something that is in focus you can try targets farther away and see if you can bring them all to focus. If you can focus on something very far in the distance then you should be quite close to the focus point for astronomical targets and can try again at night.

 

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On 10/06/2019 at 20:34, Gabe said:

Hey, I wanted to say thanks too all the people who have helped so far. I would also like to thank michael8554 for telling me that the THING is called a diagonal 😆 

 

I was wondering, if I got a Barlow lens, would that help my problem? 

Now that you know to always use the diagonal in the focuser, I don't think you really have a problem as it seems that your eyepieces reach focus. If you're wanting to use the telescope without the diagonal then you will need an extension tube rather than a barlow.  I think the light path of a 1.25" diagonal is usually around the 65-70mm mark so you will need an extension tube of this sort of length to replace the diagonal. 

If you want more magnification then the 10mm and 2x barlow is probably going to be too high for your telescope. An 8 or 9mm eyepiece might be the limit.

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On 15/06/2019 at 04:30, Ricochet said:

Now that you know to always use the diagonal in the focuser, I don't think you really have a problem as it seems that your eyepieces reach focus. If you're wanting to use the telescope without the diagonal then you will need an extension tube rather than a barlow.  I think the light path of a 1.25" diagonal is usually around the 65-70mm mark so you will need an extension tube of this sort of length to replace the diagonal. 

If you want more magnification then the 10mm and 2x barlow is probably going to be too high for your telescope. An 8 or 9mm eyepiece might be the limit.

Ok, thanks. I didn't even know that there was a such thing as an extension tube for a telescope. My only remaining question is why this is happening? I mean, how could a big company like Celestron make a scope that couldn't even focus onto Jupiter? 

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19 minutes ago, Gabe said:

Ok, thanks. I didn't even know that there was a such thing as an extension tube for a telescope. My only remaining question is why this is happening? I mean, how could a big company like Celestron make a scope that couldn't even focus onto Jupiter? 

If you are using the diagonal it should work fine. Have you tried this again yet?

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14 minutes ago, Gabe said:

Ok, thanks. I didn't even know that there was a such thing as an extension tube for a telescope. My only remaining question is why this is happening? I mean, how could a big company like Celestron make a scope that couldn't even focus onto Jupiter? 

You are always supposed to use the diagonal. With it in place the telescope can focus, there is nothing wrong. 

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