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Needed: Help choosing scope

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#1 NSObserver

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Posted 22 September 2021 - 01:14 PM

Hi all,

I am in a position to be replacing my LX200gps with a new mount (Losmandy GM811) and will be changing from a SCT to a refractor. I will be primarily imaging in a Boortle 4-5 area. I have been imaging (LRGB) with the LX200 for about 10 years using a QSI683 and LX2 OAG. My intent is to continue using the QSI (although it may be getting somewhat old and possibly in need of replacement, but that's another topic). The 3 contenders I've thought of are

1) Stellarvue 102T

2) Tele Vue NP101is

3) Takahashi 100 mm Fluorite APO

 

I would like ideas of how to make an apples to apples comparison (ie, an objective means to make a choice) as well as real life experiences with any of the scopes. Are there any strengths/weaknesses or "gotchas" I need to be aware of?

Thanks in advance for all input and help.

Ken



#2 Jim Waters

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Posted 22 September 2021 - 01:40 PM

Get the Stellarvue 102T.  This scope with the SV FR/FF would be more versatile than the Tele Vue at f/5.4.

 

IMHO Takahashi are over priced.


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#3 NSObserver

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Posted 24 September 2021 - 04:29 PM

Thanks, Jim. Just what I wanted to know.

Ken



#4 dan_1984

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Posted 24 September 2021 - 04:43 PM

Hi all,

I am in a position to be replacing my LX200gps with a new mount (Losmandy GM811) and will be changing from a SCT to a refractor. I will be primarily imaging in a Boortle 4-5 area. I have been imaging (LRGB) with the LX200 for about 10 years using a QSI683 and LX2 OAG. My intent is to continue using the QSI (although it may be getting somewhat old and possibly in need of replacement, but that's another topic). The 3 contenders I've thought of are

1) Stellarvue 102T

2) Tele Vue NP101is

3) Takahashi 100 mm Fluorite APO

 

I would like ideas of how to make an apples to apples comparison (ie, an objective means to make a choice) as well as real life experiences with any of the scopes. Are there any strengths/weaknesses or "gotchas" I need to be aware of?

Thanks in advance for all input and help.

Ken

Choose the scope that will match the camera you have. Image scale is very important



#5 SilverLitz

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Posted 24 September 2021 - 05:46 PM

Also consider the Esprit 100, which has a shorter FL (larger FoV) and faster.  It is a great bang/buck scope for AP.  I have had the Esprit 100 for 2+ years, and it has been my workhorse, as it is great for most nebulas.  I mainly use the Esprit reduced to 413mm and fast f/4.13.

 

Always consider FoV and image scale with the scope paired with your camera, and then see how this matches with your target choices.

 

I have recently added a SVX130T to compliment the Esprit for smaller targets.  SVX build and optical quality is more impressive than the Esprit, but the USA hand-built SVX's are pricier compared the class-setting, China-built, mass produced, Esprits.

 

The fluorite Tak 4" scopes have a great reputation, and seem to be some of the better value Tak scopes, but consider all of the high priced extra Tak pieces needed for AP.



#6 Jon Isaacs

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Posted 24 September 2021 - 06:53 PM

My two cents:

 

Why are you switching from the SCT to a refractor?

 

The advantage the NP-101 IS has over the other two is that it has a flat flat field of view, it's a quad, a modified Petzval.  

 

There's no field flattener to have to mess with and try to adjust, it's part of the design. 

 

The other scope in this class to consider is the Takahashi 106 FSQ. It's also a "modified Petzval" and has a very large 88 mm imaging circle.  In my opinion it's the premier 4 inch imaging imaging refractor but it's much more expensive, $6200.

 

https://www.takahash...or-telesco.html

 

Jon



#7 NSObserver

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Posted 25 September 2021 - 08:44 AM

Hi again all.

Rather than address each reply individually, I will try to address what I see as the themes presented.

I'm currently leaning toward the Stellarvue for the reasons Jim mentioned.

1) Matching camera to scope, ie image scale. Since seeing seems to always be relatively poor where I'm able to observe, the Astronomy Tools website seems to think I'm OK at the 1.56"/pix scale the Stellarvue 102T would provide (as an example) and native focal length. Not quite as good with the reducer. Note also that the QSI may be nearing retirement age which will allow me to consider other cameras in the not too distant future. But, it's working for now....

2) Value (what I get for the price). More difficult to decide here. I did look at the Esprit line. Haven't completely ruled them out.

3) Jon's question about switching from SCT to refractor. Good question, and the answer is complicated. Short version is... we have moved into a senior facility, in independent living  (a cottage). So, I've left the observatory behind and now will need to have something more portable (hence the GM811) and lighter (that's why I'm thinking refractor). I've imaged the Messier and Herschel 400 catalogs with the 8" SCT, which works for a lot of those catalogs, but many things just won't fit in the FOV. Plus, the _mounted_ LX200gps is no longer really capable of imaging; it really needs to be disassembled and greased as there is a definite metal-on-metal sound when slewing in RA. If  I'm starting over, might as well make it a new adventure where I can learn something new, while building on what I know.

If you have any more ideas, I would love to hear them. From just the responses to date, I've been able to start narrowing down the field. Might as well enjoy the process!

Thanks, again.

Ken




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