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Not enough in focus. Eyepiece extension tube?

Beginner Reflector Meade
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#1 L0ngC4t

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Posted 22 September 2022 - 03:40 PM

I am the proud owner of a Meade StarNavigator 114mm Reflector Telescope. As a proud owner of this telescope, I left it in my garage long enough that the plastic gear teeth on the focuser disintegrated. To deal with this, I bought a replacement metal focuser, complete with metal gear teeth, and after much tinkering, I got it to fit perfectly. 

 

The problem I'm running into is that the original plastic focuser seems to have had some kind of barlow lens glued to the far (inner) end of it. My new focuser has nothing on the end, and as I roll the focuser further and further in, I approach focus, but can't reach it. I'm curious if something like this:

 

https://www.amazon.c...01L0DY0RE&psc=1

 

would solve the problem I'm having, or if it would have the opposite effect. I also have a simple 2x barlow that I got as a replacement for the weird glued on one, but it goes on the near (outer) side of the focuser. Would taking that out help at all? I would simply try that, but at the moment I can't find any of my other lenses (I just moved tongue2.gif ).

 

I'm kind of clueless about some of the language surrounding this stuff (not for lack of trying, I promise), so please try to put things in simple terms where possible. Many thanks



#2 FRANKVSTAR

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Posted 22 September 2022 - 04:04 PM

I have heard that using a barlow would help you to reach focus. I am not sure however. Goodluck



#3 DLuders

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Posted 22 September 2022 - 04:19 PM

Welcome to Cloudy Nights!  smile.gif  The Meade StarNavigator 114mm Reflector has a Bird-Jones design.  It needs that corrective lens to work.  There is this YouTube video that explains it.  It has a spherical mirror, which is more suitable for longer-tube reflectors.  Most astronomers avoid telescopes having the Bird-Jones design.  


Edited by DLuders, 22 September 2022 - 04:22 PM.

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#4 ngc7319_20

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Posted 22 September 2022 - 04:23 PM

What I would suggest, is to try to place a Barlow lens in the bottom of the new focuser, like the old one had.  If you can remove the lens assembly (sometimes they just unthread) from the 2x Barlow you mention, and then try to install it in the bottom of the new focuser.  Or maybe you can get the lens assembly out of the old focuser.  Maybe wrap some tape around the lens assembly to get a tight press fit into the bottom of the focuser.

 

The Far Point extension tube may or may not work.  In any case, you would need to install a Barlow lens in it, to make it work.


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#5 Starman1

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Posted 22 September 2022 - 04:24 PM

I am the proud owner of a Meade StarNavigator 114mm Reflector Telescope. As a proud owner of this telescope, I left it in my garage long enough that the plastic gear teeth on the focuser disintegrated. To deal with this, I bought a replacement metal focuser, complete with metal gear teeth, and after much tinkering, I got it to fit perfectly. 

 

The problem I'm running into is that the original plastic focuser seems to have had some kind of barlow lens glued to the far (inner) end of it. My new focuser has nothing on the end, and as I roll the focuser further and further in, I approach focus, but can't reach it. I'm curious if something like this:

 

https://www.amazon.c...01L0DY0RE&psc=1

 

would solve the problem I'm having, or if it would have the opposite effect. I also have a simple 2x barlow that I got as a replacement for the weird glued on one, but it goes on the near (outer) side of the focuser. Would taking that out help at all? I would simply try that, but at the moment I can't find any of my other lenses (I just moved tongue2.gif ).

 

I'm kind of clueless about some of the language surrounding this stuff (not for lack of trying, I promise), so please try to put things in simple terms where possible. Many thanks

Your scope needs the magnifying lens to reduce the horrible spherical aberration from the spherical primary mirror.

It's possible the Barlow will work.

Chances are your new focuser is taller than the old focuser, which is why you need more in focus.

Can you focus with the Barlow?  If you can, leave it in the focuser and use all eyepieces with it, as the focal length of your scope will not match the Meade specifications without it.

Let us know if you can focus with Barlow in place.

 

An extension tube is the opposite of what you want.  It will require MORE in focusing.


Edited by Starman1, 22 September 2022 - 04:25 PM.

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#6 vtornado

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Posted 22 September 2022 - 04:25 PM

maybe ... you can extract the old "barlow" lens, wrap some tape around it, and friction

fit it into the new focuser ... maybe.

 

I'm not sure this lens is a barlow or something else.  It is also supposed to correct for the the fact the the StarNavigtor has a spherical mirror instead of a parabolic one.

 

I looked up a true Bird-Jones corrector and a barlow and the lenses are slightly different.  Although who is to say the these deparment store bird-jones use

the traditional corrector.

 

I would not dump any more cash into this scope without careful consideration.

 

VT.


Edited by vtornado, 22 September 2022 - 05:01 PM.

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#7 Starman1

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Posted 22 September 2022 - 04:39 PM

The Barlow is 2x if it is close to the eyepiece.

Down inside the focuser, farther from the eyepiece, a barlow lens would provide too much magnification.

The OP has a 2x Barlow.  It should be tried.


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#8 cuzimthedad

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Posted 22 September 2022 - 04:59 PM

Welcome to Cloudy Nights!


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#9 Waynosworld

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Posted 22 September 2022 - 05:17 PM

I bought a Celestron Powerseeker 127EQ when first got interested in this hobby, it is also a Bird-Jones design, it was never going to do what I wanted it to do so I gave up and bought a quality telescope, if you can find a good used 6"/8"/10" dob I think you will be a lot happier, you will be able to see things you will never be able to see with what you have.


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#10 stargazer32864

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Posted 22 September 2022 - 08:45 PM

I bought a Celestron Powerseeker 127EQ when first got interested in this hobby, it is also a Bird-Jones design, it was never going to do what I wanted it to do so I gave up and bought a quality telescope, if you can find a good used 6"/8"/10" dob I think you will be a lot happier, you will be able to see things you will never be able to see with what you have.

I think this is the best advice you can get. Start over with a quality scope. I had an 8" Orion Intelliscope. I never used the computer on it since I knew where to look 

for my favorite objects. Apertura has a quality Dobsonian in different sizes and they come with a few extras. It comes with a cooling fan, the 8" does, which will cool down your scope a lot faster than the slow way of just letting it sit there. And, our sponsor, Astronomics will give you a 10% discount on all your orders. Just make sure to talk to a live person and tell them exactly what you want. And it won't hurt to give them the item number that is listed on their website when ordering that way they don't forget because they didn't know that you're a member here. That cost me last time. My bad!!

 

~Robin


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#11 stargazer32864

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Posted 22 September 2022 - 08:50 PM

I bought a Celestron Powerseeker 127EQ when first got interested in this hobby, it is also a Bird-Jones design, it was never going to do what I wanted it to do so I gave up and bought a quality telescope, if you can find a good used 6"/8"/10" dob I think you will be a lot happier, you will be able to see things you will never be able to see with what you have.

I always thought that those Powerseekers looked similar to the Bird-Jones design. Thank you for letting me know for sure.

 

~Robin


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#12 L0ngC4t

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Posted 23 September 2022 - 11:22 AM

Thank you all so much for the useful info and advice, as well as the warm welcome. In line with much of the advice here, I think I am going to purchase a replacement telescope armed with new knowledge and research. You may be seeing another post or two from me regarding that, who knows. That said, I got this scope as a birthday gift when I turned 10, and I will probably do more tinkering with it at some point to see if I can get it at least somewhat working again. 

 

I will say that I'm pretty sure I've tried both with and without the barlow to no avail, although I'll double check that when I manage to find my eyepieces again. 

 

Thank you all again, and feel free to drop some general scope-buying advice below if you feel you have some wise words to add. 



#13 bbasiaga

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Posted 23 September 2022 - 11:52 AM

Thank you all so much for the useful info and advice, as well as the warm welcome. In line with much of the advice here, I think I am going to purchase a replacement telescope armed with new knowledge and research. You may be seeing another post or two from me regarding that, who knows. That said, I got this scope as a birthday gift when I turned 10, and I will probably do more tinkering with it at some point to see if I can get it at least somewhat working again. 

 

I will say that I'm pretty sure I've tried both with and without the barlow to no avail, although I'll double check that when I manage to find my eyepieces again. 

 

Thank you all again, and feel free to drop some general scope-buying advice below if you feel you have some wise words to add. 

you can look at Youtube for Ed Ting's videos on scopes for beginners.  He has some recommendations.  

 

I like to recommend thsi one:  https://www.bhphotov...02mm_f_9_8.html

 

My daughter has it and a friend got one.  It has a decent mount with slow motion controls, and the OTA is not bad for the price point.  Get yourself a pocket sky atlas and a moon filter to go with it.  Eventually you may want a better finder scope.  The red dot it comes with is passable, but not great.  That's true of basically everything in this price range.  It has the 'universal' style finder mount though, so there are lots of options.  If you want to spend more, there are similar versions with their Starsense system, or other go-to/computerized options.  

 

Brian


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#14 stargazer32864

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Posted 23 September 2022 - 08:14 PM

Thank you all so much for the useful info and advice, as well as the warm welcome. In line with much of the advice here, I think I am going to purchase a replacement telescope armed with new knowledge and research. You may be seeing another post or two from me regarding that, who knows. That said, I got this scope as a birthday gift when I turned 10, and I will probably do more tinkering with it at some point to see if I can get it at least somewhat working again. 

 

I will say that I'm pretty sure I've tried both with and without the barlow to no avail, although I'll double check that when I manage to find my eyepieces again. 

 

Thank you all again, and feel free to drop some general scope-buying advice below if you feel you have some wise words to add. 

You do know that when you get your new toy, it's policy on here, (well, not really) to post some pictures. We like seeing new family members. flowerred.gif

 

Welcome to CN~Robin


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#15 L0ngC4t

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Posted 24 September 2022 - 08:30 PM

You do know that when you get your new toy, it's policy on here, (well, not really) to post some pictures. We like seeing new family members. flowerred.gif

 

Welcome to CN~Robin

Will do! It might be a little while, but it also might not. I'm thinking I'll probably end up going for a 8-10" used dob like Waynosworld said.



#16 Spile

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Posted 25 September 2022 - 03:29 PM

I think the Dobsonian is an excellent choice for visual https://astro.catshi...se-a-dobsonian/




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