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NP101 & NP101is

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13 replies to this topic

#1 hongxu chen

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Posted 14 July 2019 - 06:35 AM

Except the focuser, what is the difference between Televue NP101is and non-is version? I notice that Starlight has NP101 focuser upgrade scheme. Will the Feather Touch improve the non-is version to as good as IS version?

#2 Jon Isaacs

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Posted 14 July 2019 - 06:45 AM

Except the focuser, what is the difference between Televue NP101is and non-is version? I notice that Starlight has NP101 focuser upgrade scheme. Will the Feather Touch improve the non-is version to as good as IS version?

I believe the difference between the NP-101 and the NP-101is is the diameter of the optics of the rear "Petzval" lens.  This essentially functions as a perfectly matched flattener/reducer.  The IS has larger diameter optics and is thus capable of illuminating a larger field of view.

 

Jon 


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#3 Spikey131

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Posted 14 July 2019 - 07:01 AM

For visual use, the NP101 is as good as the NP101is.

 

As Jon wrote, TV improved the optics in the “is” version to give a wider view for imaging.


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#4 hongxu chen

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Posted 14 July 2019 - 09:01 AM

I believe the difference between the NP-101 and the NP-101is is the diameter of the optics of the rear "Petzval" lens. This essentially functions as a perfectly matched flattener/reducer. The IS has larger diameter optics and is thus capable of illuminating a larger field of view.

Jon


I am using 16200 CCD. Is the non-is good enough for me?

#5 HydrogenAlpha

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Posted 14 July 2019 - 11:35 AM

I am using 16200 CCD. Is the non-is good enough for me?


The 16200 has a fairly large chip and is rather heavy. You should get the IS

#6 allen g

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Posted 14 July 2019 - 03:18 PM

I asked that question to David Nagler when I was purchasing the np101.  He said for visual viewing there is no difference. 



#7 hongxu chen

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Posted 14 July 2019 - 10:11 PM

The 16200 has a fairly large chip and is rather heavy. You should get the IS


I bought the NP101 ten years ago for visual viewing. Now I have a chance to get a good price 16200 CCD. So I am planing for astrophotography. I don’t know whether my scope is suit for that CCD or not. I would accept improve it like change the focuser to fully use this CCD, but not trade in it for an IS version or even a TAK. If my scope can not hold this CCD, I will just stop doing anything. Or I would not help myself to burn money to upgrade the scope to match this CCD after buying it. Then burn money to upgrade the CCD to match the new scope. Endless cycle, until sell my soul to this devil hobby.

#8 HydrogenAlpha

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Posted 14 July 2019 - 10:45 PM

I bought the NP101 ten years ago for visual viewing. Now I have a chance to get a good price 16200 CCD. So I am planing for astrophotography. I don’t know whether my scope is suit for that CCD or not. I would accept improve it like change the focuser to fully use this CCD, but not trade in it for an IS version or even a TAK. If my scope can not hold this CCD, I will just stop doing anything. Or I would not help myself to burn money to upgrade the scope to match this CCD after buying it. Then burn money to upgrade the CCD to match the new scope. Endless cycle, until sell my soul to this devil hobby.

If you eventually intend to upgrade to the NP101IS, you can look for a used unit so you don't need to spend too much on the upgrade. The price difference between a used NP101 and NP101IS is not unreasonably large. 

 

Also, you don't need to upgrade the CCD just to max out the image circle. There are many people happily using FSQ106s with small sensors, despite having the 88mm image circle. 

 

By the way, how much experience do you have with astrophotography? Shelling out for a 16200 is already quite a substantial investment, given that there are many other more affordable options (CMOS-based cameras) in the market. 



#9 Jeff Morgan

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Posted 30 July 2020 - 06:53 PM

Kind of an old thread to bump, but I am researching the NP and had a relevant question:

 

Can the standard NP be used with a 55 Plossl (or any other 46mm field stop eyepiece)?

 

Any vignetting issues?



#10 imtl

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Posted 30 July 2020 - 08:56 PM

You can use it. But with a 10.1mm exit pupil. Unless you are a cat I don't see what advantage that would give you.

The Pan 41mm is already at 7.6mm exit pupil and it is a 46mm field stop the same as the 55 plossl.

Eyal



#11 Jon Isaacs

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Posted 30 July 2020 - 09:04 PM

Kind of an old thread to bump, but I am researching the NP and had a relevant question:

 

Can the standard NP be used with a 55 Plossl (or any other 46mm field stop eyepiece)?

 

Any vignetting issues?

 

I use it the 41 mm Panoptic in my standard NP-101.

 

The 41 mm Pan has a slight darker ring at the field stop in all my refractors but other than that, I see no vignetting. I think it's an issue with the clear aperture of the diagonal and the field stop. Ideally, the diagonal has a greater clear aperture than the field stop.

 

Jon



#12 BravoFoxtrot

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Posted 30 July 2020 - 09:51 PM

You can use it. But with a 10.1mm exit pupil. Unless you are a cat I don't see what advantage that would give you.

The Pan 41mm is already at 7.6mm exit pupil and it is a 46mm field stop the same as the 55 plossl.

Eyal

NV?



#13 M44

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Posted 30 July 2020 - 10:43 PM

NV?

Yes. It is for NV. Night vision device can take up to 21mm exit pupil.



#14 Jeff Morgan

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Posted 30 July 2020 - 11:21 PM

Yes. It is for NV. Night vision device can take up to 21mm exit pupil.

 

Exactly so. Using the Tele Vue 67mm conversion lens.

 

I was wondering if it required the newer "is" version, but sounds like the older NP scopes will be effective.




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