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  #1  
Old 06-11-2017, 07:57 AM
drrockso (John)
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Another new person

Hey Folk!

Thanks for building up such an informative community. It has been very helpful so far.

I recently bought a used 150EQ. It was nice and cheap and meant that if we (the family) lost interest, our buy in was low. The mount is a bit wobbly (even wind) and the finder scope is utter rubbish(plastic with so much play that adjusting it using the knobs moves the FS in its mount completely moving alignment). But the scope works :-)

But as it seems, I need more. Last night we managed to see Saturn through the 10mm EP and that was great but man it was small. So i'm looking to buy new Barlow I think, to double or triple the existing 10&20mm EPs we have.

Now I dont particularly want to buy more cheap ... stuff so what would be recommended and while i'm asking questions. Does the Barlow affect the FoV at all?
I understand I will be spending more then I did on the scope on any EPs and Barlow's and I guess that's ok.

Cheers all

John
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  #2  
Old 06-11-2017, 02:31 PM
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Allan_L (Allan)
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Quote:
Originally Posted by drrockso View Post
Hey Folk!
Thanks for building up such an informative community. It has been very helpful so far.
I recently bought a used 150EQ. It was nice and cheap and meant that if we (the family) lost interest, our buy in was low. The mount is a bit wobbly (even wind) and the finder scope is utter rubbish(plastic with so much play that adjusting it using the knobs moves the FS in its mount completely moving alignment). But the scope works :-)
But as it seems, I need more. Last night we managed to see Saturn through the 10mm EP and that was great but man it was small. So i'm looking to buy new Barlow I think, to double or triple the existing 10&20mm EPs we have.
Now I dont particularly want to buy more cheap ... stuff so what would be recommended and while i'm asking questions. Does the Barlow affect the FoV at all?
I understand I will be spending more then I did on the scope on any EPs and Barlow's and I guess that's ok.
Cheers all
John
Hi john,
Welcome to IceInSpace
(from a fellow bean-counter).

Your current scope 150mm aperture 750mm focal length 10mm eyepiece will be giving you approximately 75 times magnification with a true field of view of about .67 of a degree ( or 40 arc minutes). [assuming a plossl with 50 degree apparent field of view].

With that setup, you could add a 2 times barlow and get a satisfying 150 magnification, and your field of view is halved to about .33 of degree.
Any further magnification may not be so satisfying.
Problem is, with a shaky mount the wobbles will be amplified and the target will pass through the field of view pretty quickly.
Not to mention atmosphere instability probably means you get a larger image but not clearly defined.

I mainly use Televue eyepieces (circa $450 and up), but there are a lot of people here who use more economical brands and claim as good results.
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  #3  
Old 06-11-2017, 02:48 PM
drrockso (John)
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Quote:
Originally Posted by Allan_L View Post
Hi john,
Welcome to IceInSpace
(from a fellow bean-counter).

Your current scope 150mm aperture 750mm focal length 10mm eyepiece will be giving you approximately 75 times magnification with a true field of view of about .67 of a degree ( or 40 arc minutes). [assuming a plossl with 50 degree apparent field of view].

With that setup, you could add a 2 times barlow and get a satisfying 150 magnification, and your field of view is halved to about .33 of degree.
Any further magnification may not be so satisfying.
Problem is, with a shaky mount the wobbles will be amplified and the target will pass through the field of view pretty quickly.
Not to mention atmosphere instability probably means you get a larger image but not clearly defined.

I mainly use Televue eyepieces (circa $450 and up), but there are a lot of people here who use more economical brands and claim as good results.
Is there anything I can do to sure up the mount?

Once I get a decent Barlow or Powermate. I guess I'll need to buy a couple of decent EP's to open up that FOV a bit.
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  #4  
Old 06-11-2017, 04:27 PM
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Allan_L (Allan)
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Quote:
Originally Posted by drrockso View Post
Is there anything I can do to sure up the mount?
I have heard people say they hang a weight on a string from under to scope to get more stability. Haven't tried it myself.
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  #5  
Old 06-11-2017, 04:57 PM
xelasnave's Avatar
xelasnave
Gravity does not Suck

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Join Date: Mar 2005
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Quote:
Originally Posted by drrockso View Post
Hey Folk!

Thanks for building up such an informative community. It has been very helpful so far.

I recently bought a used 150EQ. It was nice and cheap and meant that if we (the family) lost interest, our buy in was low. The mount is a bit wobbly (even wind) and the finder scope is utter rubbish(plastic with so much play that adjusting it using the knobs moves the FS in its mount completely moving alignment). But the scope works :-)

But as it seems, I need more. Last night we managed to see Saturn through the 10mm EP and that was great but man it was small. So i'm looking to buy new Barlow I think, to double or triple the existing 10&20mm EPs we have.

Now I dont particularly want to buy more cheap ... stuff so what would be recommended and while i'm asking questions. Does the Barlow affect the FoV at all?
I understand I will be spending more then I did on the scope on any EPs and Barlow's and I guess that's ok.

Cheers all

John
Welcome from me John.

May I suggest you dont run off and buy stuff but concentrate on getting what you have working as best you can get it..the mount for example presumably can be made solid, I have fixed a couple with simple things like more weight tighten this or that... if you find the mount no good for the stuff you have you may want to fix your site on a better mount...everything turns on the mount...so before you spend money think how that could go to a good mount...

But have fun with what you have ..even if the mount is a beast try and work around it and see what you can see. To do so will help you work out direction.

Good luck its nice to have you here.

alex
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  #6  
Old 06-11-2017, 07:47 PM
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ChrisV (Chris)
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+1 for a milk container full of water hanging off the bottom of the mount. I'm sure it stabilised my old mount ...
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  #7  
Old 07-11-2017, 05:24 AM
AEAJR (Ed)
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Location: Long Island, New York, USA
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Cool

Quote:
Originally Posted by drrockso View Post
Hey Folk!

Thanks for building up such an informative community. It has been very helpful so far.

I recently bought a used 150EQ. It was nice and cheap and meant that if we (the family) lost interest, our buy in was low. The mount is a bit wobbly (even wind) and the finder scope is utter rubbish(plastic with so much play that adjusting it using the knobs moves the FS in its mount completely moving alignment). But the scope works :-)

But as it seems, I need more. Last night we managed to see Saturn through the 10mm EP and that was great but man it was small. So i'm looking to buy new Barlow I think, to double or triple the existing 10&20mm EPs we have.

Now I dont particularly want to buy more cheap ... stuff so what would be recommended and while i'm asking questions. Does the Barlow affect the FoV at all?
I understand I will be spending more then I did on the scope on any EPs and Barlow's and I guess that's ok.

Cheers all

John
Welcome to the universe. While your first scope may not be the top of the line it is certainly good enough to get you started.

With a 150 mm aperture the scope should be capable of going up to 300X. Unfortunately the atmosphere will often prevent you from working that high.

Transparency and Seeing - Note that atmospheric conditions, rather than your telescope, will often be the limiting factor on practical magnification for any given observing session. When the atmosphere is turbulent, poor “seeing” conditions, you may find that the image breaks down too much above a certain magnification regardless of the size of your telescope. Transparency is also a factor that can be affected by humidity, air pollution and thin clouds that you may not be able to see. My 8”/203 mm often tops out around 180X due to “seeing” and transparency issues. However, under exceptional conditions I have been able to go 300X or higher.

As for field of view. Some simple formula will help you.

Focal Length scope / Focal length eyepiece = magnification

Apparent field of view, AFOV, is a specification provided with most eyepieces.

AFOV/ magnification = field of view.

So, as you go up in magnification you go down in field of view. This is a matter of physics.

The only way to address this is to buy eyepieces that have wider AFOV specs. This usually raises the price.


Selecting an eyepiece - Orion telescope
This is a very general discussion of eyepieces and why there are a variety of designs. Ignore that it is done by Orion as everything he says applies to virtually all eyepieces from all manufacturers.
https://www.youtube.com/watch?v=m7u9Q5hV7yc



Barlow


Considering the 150 mm aperture of your scope and your current eyepieces I would suggest a 3X barlow. That would take you to 37X, 75X, 111X, 225X using your current eyepieces. Under reasonably good skies 225 shoudl be a useful magnification.


I am in the USA so you will have to check local suppliers. Here is a sample.
http://agenaastro.com/catalogsearch/...?q=3X%20barlow

GSO and Antares have very good reputations at moderate prices.


Eyepieces

I am very partial to zoom eyepieces. I have two. The Celestron and the Baader Hyperion 8-24.
http://agenaastro.com/eyepieces/zoom...anetarium.html


Eyepiece Strategy


For each of my scopes I have one or two low power wide view eyepieces. For your scope that might be a 32mm Plossl Plus your 20 mm.

Then I have a zoom which I use for 8-24 mm but frankly I use it mostly in the 8-18 mm range.

Then, for high power I put the zoom in a barlow appropriate to the scope I am using. In your case I have recommended a 3X barlow.

In your scope that would give you 31.5X to 93.75X. Drop it in a 3X barlow and you have 94X to 281.5X You would have every magnification between 31.5X and 281.5X.


  • I never expected the zoom eyepiece to become my primary eyepiece, but it has.
  • The Celestron 8-24 zoom is good and comparable to my Plossl eyepieces ($65)
  • The Baader Hyperion is great and comparable to my Explore Scientific eyepieces ( $289)
  • Watching doubles split as I rotate the barrel is wonderful
  • One filter serves over a wide range of magnifications, no screwing and unscrewing to try other eyepieces
  • Moving smoothly from and between small changes in magnification helps when seeing is not the best
  • I am always working at the optimum magnification for this target.
  • Sharing the view with others is easier, especially in my manual tracking Dob - I hand it over at low mag so it stays in the view longer. They zoom back in to whatever magnification works best for them.
  • My eyepiece case has been greatly simplified
  • Kids love the zoom
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  #8  
Old 07-11-2017, 08:50 AM
drrockso (John)
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Cheers for all the responses. As soon as the clouds clear and we get some good nights for viewing (tomorrow night maybe) I will be very interested in trying out hanging a water bottle from scope mount to see how that effects the wobbles. I have high hopes it should sort it out quite well.

3 more questions.

1 - If hanging a water bottle doesn't correct the wobbles. What types of stands would I need to replace it with(used/new, brands & models)?

2 - Mine is a f4.9(f5)? Will there be barlows, powermates or EPs that will not work with this ratio? I read on an EP or Barlow that it was compatible with fast f ratio (maybe 3 or 4.9) which made me think others wouldn't be, but its not something I have read about yet.

3 - I hear Barlows used a lot.. but not so much powermates? Why is this? Isn't a powermate superior to a Barlow?

I guess from here my plan is to get a the stand stable.. I can deal with the rubbish Finder Scope for the time being while I focus on easy to find objects and get a Barlow or power mate once I have eliminated the wobbles from the mount. But I guess this will then give me issues with FOV.

Cheers guys.

Last edited by drrockso; 07-11-2017 at 09:00 AM. Reason: Added a Q about Barlows and Powermates
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  #9  
Old 07-11-2017, 08:59 AM
AEAJR (Ed)
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Cool

Eyepieces and barlows will generally work with most scopes. The challenge is how good the image looks around the edge most of the time. Once you get below F5 the edges are harder to correct. 4.9 is close enough.

The wider the AFOV typically the higher the price. The better corrected that wide eyepiece is the more it will cost.

If you are less fussy, good center 75% is good enough, with some distortion at the outer edges, then lower cost eyepieces may be fine for you.

If you want near perfect all the way to the edge and a wider AFOV then you want to buy things like the Meade 5000 UWA, Explore Scientific 68 or 82, Pentax XW, Tele Vue type eyepieces. They will stand up best to the F5 and below scopes. But a basic Plossl will give you a pretty good image too, at a fraction of the cost.

When you get into larger scopes, 12" and above, and you are down in the mid to lower 4.X Focal Ratios then you start talking about coma correctors.


There are Fords and there are Lincolns and there are Ferraris. They will all get you to the supermarket. They just do it a little differently and with a little different experience.

Your budget will determine what you will be driving in your focuser. Always start with the budget. Always!
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  #10  
Old 08-11-2017, 06:02 AM
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ZeroID (Brent)
Lost in Space ....

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Hi John, another welcome.
I hung about 5 kg off the bottom of my first scope\tripod and it helped quite a bit but to be honest the only real solution was to buy up the ladder and get better equipment. But I suggest you persevere for at least a short while till you learn a bit more and also learn the limitations of your existing setup so you make good decisions for your next buy.

Noone here has suggested you find a local astro club but if you can then it's worth connecting with them and attending one of their viewing nights. I'm sure any of them would be happy to help spend your ... err help you determine any upgrades and let you view and compare options.


There are some cheaper Eyepieces that do perform quite well compared to the normal plossls. I have the GSO 15mm and 20 mm Superviews which normally price below $100 and have a good wide field and edge correction. They also work well with Barlows and most scopes. I image mostly but those two are my preferred EPs for 90% of all my viewing and the disparate sizes gives me various options with a barlow.

EDIT
Here's the Bintel page with the EPs' renamed as Bintel but only $53 each, you only need the 1.25" 15mm and 20mm. Barlow's also available from other pages.
https://www.bintel.com.au/product/bi...s-1-25-2-inch/

Last edited by ZeroID; 08-11-2017 at 06:36 AM. Reason: Added link
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  #11  
Old 08-11-2017, 05:49 PM
Littlegreenmen (Paul)
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My 5cents worth.Just picked up a GSO 2" 2x barlow to compliment my ES eyepieces.Best bargain as not only multiplying my focal range but still allows plenty of eye relief. No problems with balance in my 12" dob.
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  #12  
Old 08-11-2017, 07:20 PM
drrockso (John)
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Guys cheers for the replys.

I'd definitely be keen to catch up with others but their isn't a club/group or otherwise *yet in Toowoomba.

It's been cloudy the last couple of nights so i'm yet to see how well weighting down the scope will go.

I have been looking around and as far as barlows go i'm edging towards this TV 3x Barlow. <- Whats peoples thoughts. Keeping in mind that down the track it could be used in another scope.

No-one seems to have mentioned Powermates yet? What is this beast that claims all the benefits of the barlow and no drawbacks.

These bintel EPs. How are they compared to say Celestron or Baader?
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  #13  
Old 08-11-2017, 10:54 PM
gaseous (Patrick)
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There’s a pretty good thread on the Cloudy Nights forum about the Barlow/powermate difference - it has to do with the internal lens configuration. Might be worth a look.
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  #14  
Old 09-11-2017, 10:15 AM
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ZeroID (Brent)
Lost in Space ....

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Quote:
Originally Posted by drrockso View Post
These bintel EPs. How are they compared to say Celestron or Baader?
I haven't got any Baader EPs, a few Celestron plossls. I'd say the SV's compare very well with the Celestron gear, they are made by GSO and in fact they probably all come out of the same factory in China anyway.

But they have good eye relief, are reasonably flat to the edge of the field and for beginners especially won't break the piggy bank while they see if Astronomy is for them. They were certainly good enough on my first 114\f8 Newt on an EQ3 to get me hooked and were a huge improvement over the supplied factory plossl that came with it.. I still use them the most if I ever eyeball the skies. I sometimes do that while the camera is running a sequence. I have an 150\f6 Newt, a 200\f8 Newt and an 80\f11 Refractor to also play with.
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