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Tele Vue NP101

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#151 Jon Isaacs

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Posted 07 October 2020 - 04:26 AM

Taking a closer look, the Tele Vue plate is only tapered on one side - explaining the lack of holding power (Vixen comparison photo attached).

 

I think I will give this a try tonight (very gingerly of course), but I need something a bit more secure - and longer to accommodate the varying loads the scope will carry.

 

goodjob.gif

 

Jeff:  

 

Thank you for noticing that. 

 

Most interesting.  I had never noticed that the TeleVue Vixen adapter was single sided.  It does seem to work but I don't like it, it's actually quite disturbing.. Just the other night, I found the scope was loose and I nearly lost it.  I had no idea why, now I know.    I have no idea what the logic is... 

 

Ironically, when I first got my NP-101, I just drilled mounting holes in an old cheapie Vixen cast Dovetail.  It worked fine but when I saw a TeleVue adapter on Astromart, I bought it, thinking it was an upgrade.

 

If you look closely at this photo, you can see the tabs on the ends of the cast Vixen dovetail peaking out.

 

6213871-NP-101 with SV MG-2.jpg

 

As of now, I no longer think it's an upgrade and I will not be using the NP-101 until l replace or modify the TV adapter.  In non-pandemic times, I would be visiting my machinist friends in the morning.  

 

I may try to make a jig and then use a belt sander to put an angle on the flat side. 

 

Jon


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#152 25585

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Posted 07 October 2020 - 10:38 AM

When I bought my TV-85 Renaissance, its previous owner had M6 bolts long enough to go through a short Vixen style bar's slots, into the 2 M6 holes on bottom of the TV clamshell.



#153 Jeff Gardner

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Posted 07 October 2020 - 10:50 AM

When I bought my TV-85 Renaissance, its previous owner had M6 bolts long enough to go through a short Vixen style bar's slots, into the 2 M6 holes on bottom of the TV clamshell.

TV clamshell threads are 1/4-20 not metric unless someone re-tapped the holes.



#154 Oscar56

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Posted 07 October 2020 - 11:10 AM

Isn't the TeleVue plate specifically designed to mate with the Porta mounts?  This is a photo of my Porta II mount which has the flat edge on the top and the beveled edge on the bottom.

 

 

131059F6-A68D-4E6F-9239-F900DE2CA5EB_1_105_c.jpeg


Edited by Oscar56, 07 October 2020 - 11:10 AM.


#155 Jeff Morgan

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Posted 07 October 2020 - 02:31 PM

Well Good News and Bad news.

 

Given the time it took to locate a Vixen rail to fit and the early moonrise, I settled for the backyard instead of driving to the dark site. A bright night, 20.1 on the SQM. Sadly, lots of people moving here and lots of new developments.

 

Time being brief I wanted to work the scope out as much as possible, first with a few cell phone photos through the 55 Plossl (with Tele Vue's 67mm conversion lens for NV) and NV eyepiece, then switch to conventional at moonrise.

 

I had an uneasy feeling when I could not get the camera focus as sharp as I would have liked.

 

The Good News is the field is nice and flat. It did take a few nice photos. Since this is not the NV forum I'll keep the attachments to a minimum to show the focus. Both 1/3 second exposures. First is northwest Cygnus in h-alpha, centered on the Propeller nebula. The ISO is lower to match the visual impression. The second is w/out filter centered on M39. Magnification in this FOV is about 5 degrees.

Attached Thumbnails

  • IMG_6698.jpeg
  • IMG_6712.jpeg

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#156 Jeff Morgan

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Posted 07 October 2020 - 03:11 PM

The Bad News

 

Switching to conventional I noticed the stars were not quite round with a 26 Nagler. Flared ever so slightly in the 7-8 o'clock position. This pattern repeated in all eyepieces.

 

The diagonal I was using is a fairly new Baader BBHS that I use with my TMB 130, and I have also used it while DPAC testing my old TMB LOMO SV80. It is a proven diagonal.

 

Using a 3.3 mm Takahashi TOE to star test, inside of focus there is a brightening of the rings at about the 1 or 2 o’clock position.

 

At focus, diffraction rings are only visible thru the 6 o’clock and 9 o’clock position.

 

Outside of focus the pattern was less distinct, though it resembled the inside focus image (but again, less distinct).

 

I called Tele Vue and described it. They said it sounded like decollimation, but said they would need to see the scope on the bench.

 

The fee for this service is $395 plus return shipping of $50 (if you still have the original boxes, which I do). Turn time is currently running around 10 days from receipt, so this new moon window is toast.

 

I used a Cheshire on it today (straight thru configuration), confirming what saw last night. Slight decollimation. I don't know if it is the front or rear elements (I suspect the front).

 

Otherwise the scope is in very good condition, just a few minor scuffs (which were both disclosed and not very noticeable at all). Very nice focuser. I like the scope quite a bit. Should fit well with NV observing, and I want to buy a CMOS camera in the future. Getting started in imaging is actually is more of a driving factor for me.

 

The seller has been very accommodating, and we have reached agreement on a solution. And yes, I would do business with him again (these things do happen, and it could have happened in transit to me). I have decided to keep the scope.

 

I read Jon's thread on re-collimating. If the scope was an older unit I would be tempted. But this one appears to be very recent production. All things considered, I am going to call Discretion the better part of Valor and send it back to Tele Vue this afternoon.


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#157 Jon Isaacs

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Posted 07 October 2020 - 04:57 PM

Jeff:

 

I still have jig. I could send it to you.. 

 

Jon



#158 Jon Isaacs

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Posted 07 October 2020 - 05:07 PM

Isn't the TeleVue plate specifically designed to mate with the Porta mounts?  This is a photo of my Porta II mount which has the flat edge on the top and the beveled edge on the bottom.

 

 

attachicon.gif131059F6-A68D-4E6F-9239-F900DE2CA5EB_1_105_c.jpeg

 

There are plenty of clamps that are angled on both sides. The Portamount is marginal for the NP-101.. 

 

I spent about 15 minutes with a grinder. It ain't pretty but it ain't coming loose either.  I'll clean it up with a flat file when I can find one.

 

 

IMG_07102020_150329_(680_x_1080_pixel).jpg

 

Jon


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#159 25585

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Posted 07 October 2020 - 06:19 PM

Jeff, my decision to not buy a NP is reinforced from your findings.

 

Has anyone had collimation trouble with the SDF or TV-101? Is decollimation just a NP issue, if so why?


Edited by 25585, 07 October 2020 - 06:21 PM.


#160 JoeBftsplk

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Posted 07 October 2020 - 06:43 PM

Yeah, I think Oscar56 is right. Not only do the beveled and flat side match up but there's a notch on the flat side that the Portamount retention screw fits right in. If you get things lined up correctly, The Televue-Vixen adapter is as secure as it can be. 

 

OTOH, if the mount arm is on the left side of the scope, things are reversed. Depending on design, alignment of bevels and retention screws may not be possible.



#161 earlyriser

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Posted 07 October 2020 - 06:44 PM

Jeff:

 

I still have jig. I could send it to you.. 

 

Jon

For $450 bucks, I’d borrow the jig and give it a shot. Worst case, you can’t fix it and you send it in anyway. 


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#162 Jon Isaacs

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Posted 07 October 2020 - 06:55 PM

Jeff, my decision to not buy a NP is reinforced from your findings.

 

Has anyone had collimation trouble with the SDF or TV-101? Is decollimation just a NP issue, if so why?

 

My guess is that it's potentially an issue with any of them.  It's probably the most apparent with with the NP-101 since it has the best optics at high magnifications.

 

Jon


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#163 Scott99

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Posted 07 October 2020 - 07:03 PM

There is no more reason to be concerned about miscollimation with a Petzval than any other refractor that is not set up for end-user collimation.  And while “some on CN” bring this up a lot, it never seems to be anyone who actually had a problem.

I guess we've taken care of that with this thread! 


Edited by Scott99, 07 October 2020 - 07:04 PM.


#164 Jon Isaacs

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Posted 07 October 2020 - 07:06 PM

Yeah, I think Oscar56 is right. Not only do the beveled and flat side match up but there's a notch on the flat side that the Portamount retention screw fits right in. If you get things lined up correctly, The Televue-Vixen adapter is as secure as it can be. 

 

OTOH, if the mount arm is on the left side of the scope, things are reversed. Depending on design, alignment of bevels and retention screws may not be possible.

 

It maybe that it was designed to only fit Vixen mounts, they seem to use a single main screw to secure scope.

 

Nonetheless,  as you say, if mounted upside down, it's not good and it's certainly not good used with many Vixen compatible clamps that are double sided. There ought to be a warning of some sort. 

 

 You can be sure that this issue will be well publicized by me.  It's a disaster waiting to happen. It nearly happened to me just the other day.. 

 

Jon


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#165 Jeff Morgan

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Posted 07 October 2020 - 11:24 PM

Jeff, my decision to not buy a NP is reinforced from your findings.

 

While a risk, it can happen to any brand of refractor. 

 

And some refractors don't have collimation screws - my Astro-Physics Star12 was such a scope. In that case, one has to shim the focuser or objective cell - or send it back to AP.


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#166 25585

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Posted 08 October 2020 - 05:30 AM

It maybe that it was designed to only fit Vixen mounts, they seem to use a single main screw to secure scope.

 

Nonetheless,  as you say, if mounted upside down, it's not good and it's certainly not good used with many Vixen compatible clamps that are double sided. There ought to be a warning of some sort. 

 

 You can be sure that this issue will be well publicized by me.  It's a disaster waiting to happen. It nearly happened to me just the other day.. 

 

Jon

Any mount or fixing using a single screw securement is risky. The best securing is multiple securing, 2 or more. Tele Vue fork mounts have 2 bolts securing the clamshell to the platform, and those are bolted by 2 or 3 bolts at each end to their adjacent yoke sides.



#167 Jon Isaacs

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Posted 08 October 2020 - 05:44 AM

Any mount or fixing using a single screw securement is risky. The best securing is multiple securing, 2 or more. Tele Vue fork mounts have 2 bolts securing the clamshell to the platform, and those are bolted by 2 or 3 bolts at each end to their adjacent yoke sides.

 

The single 5/16 inch screw that secures the Vixen Dovetail to the Vixen shoe is plenty to secure the scope. This is a locking bolt and not a bolt that attaches the dovetail to the scope.  There is a second smaller safety screw.

 

The problem is geometry.  If the TV adapter is installed upside down, then you have a flat against the dovetail and while it will hold if everything is tight, if it is not installed just right, it can come free.  

 

The second safety screw doesn't help.. 

 

Jon



#168 Larry Adams

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Posted 08 October 2020 - 10:41 AM

This is the link to the D dovetail plate I use to mount my TV85 on my Losmandy G8. It is made specifically for the TV clamshell and attaches with three 1/4-20 socket head screws and is very solid. It also has 1/4-20 tapped holes on each end to install stops on the bottom to prevent sliding out of the saddle should it come loose for some reason. Should work fine for the NP101 too.

 

https://farpointastr...evue-clamshell/



#169 Scott99

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Posted 08 October 2020 - 01:13 PM

While a risk, it can happen to any brand of refractor. 

 

And some refractors don't have collimation screws - my Astro-Physics Star12 was such a scope. In that case, one has to shim the focuser or objective cell - or send it back to AP.

Did it have to go back to AP for collimation though?  Star 12's and Traveler lens cells don't have adjustments.  I believe they're designed to be fixed in place and cannot migrate out of alignment.  But we digress.......



#170 Jeff Morgan

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Posted 08 October 2020 - 06:04 PM

Did it have to go back to AP for collimation though?  Star 12's and Traveler lens cells don't have adjustments.  I believe they're designed to be fixed in place and cannot migrate out of alignment.  But we digress.......

 

I was able to collimate the Star12 with help from SkyRanger. Like collimating a large Newtonian, very helpful to have someone at the Cheshire end giving feedback.

 

It would have been a lot easier with traditional push-pull screws!


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#171 25585

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Posted 09 October 2020 - 06:55 AM

My guess is that it's potentially an issue with any of them.  It's probably the most apparent with with the NP-101 since it has the best optics at high magnifications.

 

Jon

Interesting point. I have read about the TV 101 being better than SDF, but no comparison between TV101 and NP101 optically, for visual use.



#172 Oscar56

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Posted 02 November 2020 - 03:53 PM

After much thought, consideration and research I pressed the "buy" button on a new NP101is last week.  It should arrive by mid November.

 

I would have liked to have purchased a gently used scope but I only recall one NP101is being advertised in Canada over the past 4 years.  Private sellers in the US seem hesitant to ship to Canada, besides they get snapped very quickly anyway.

When I placed my order through my astronomy store they were informed by Televue that their was approximately a 4 week wait time.  After 4 weeks + 1 day TV contacted my astronomy store that my NP101is had been completed.  

 

No word yet on when I will see the scope.


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#173 NC Startrekker

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Posted 02 November 2020 - 08:12 PM

Grant, I realize from my own experiences that it can be frustrating and disappointing when something you have been looking forward to gets delayed. But, try to be patient. Much of the Astro market has been impacted by COVID, from supply to manufacturing to shipping. Televue has been impacted like most. If you check the retailers, you will find quite a few popular items are out of stock and on back order. The ability of suppliers to get materials and products to them is very unpredictable. As an owner of an NP-101 myself, I'm sure in the end that your wait will have been worth it.  Best. Alan



#174 Jeff Morgan

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Posted 03 November 2020 - 01:12 AM

When I placed my order through my astronomy store they were informed by Televue that their was approximately a 4 week wait time.  After 4 weeks + 1 day TV contacted my astronomy store that my NP101is had been completed.  

 

No word yet on when I will see the scope.

 

When I talked to John he said about 10 days to re-collimate mine.

 

Another call and Yolanda said about 4 weeks.

 

Yolanda was closer. Hopefully accurate as the November dark sky window is opening.


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#175 Tyson M

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Posted 03 November 2020 - 01:19 PM

When I talked to John he said about 10 days to re-collimate mine.

 

Another call and Yolanda said about 4 weeks.

 

Yolanda was closer. Hopefully accurate as the November dark sky window is opening.

Once you get it back it will be perfect though. Beautiful wide, flat fields, and able to do high power double stars/planetary work as well.


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