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Tele Vue NP101

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#201 Pezdragon

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Posted 30 December 2020 - 04:03 AM

I too built and used that jig when I decided my NP was just a hair off. I talked to TeleVue and they encouraged me to try. The hardest part really was breaking free the 3 screws holding the lens cell. 2 were not too challenging but the third was a several day head scratcher and worry until it finally cracked free before the head was to damaged to engage the Allen wrench. I replace the 3 with stainless steel and used no loctite or epoxy and has held fine for the last 9 years.

  I did have to wait for a good night of stable seeing to nudge the collimation in using Polaris but it’s very satisfying to know I can do it at will. I found the jig to be an aid but not absolutely necessary as light taps with a small block of wood at the right place also works.


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#202 25585

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Posted 31 December 2020 - 04:41 AM

Is it usually the objective lenses out of collimation themselves, or are you compensating for mis-collimated inner lenses? 



#203 Jon Isaacs

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Posted 31 December 2020 - 05:00 AM

Is it usually the objective lenses out of collimation themselves, or are you compensating for mis-collimated inner lenses? 

 

As Chris explained in his most recent post:

 

"In other words, you neither have any way nor need of adjusting the front pair of lenses relative to each other, nor the respective rear pair relative to each other - the only available collimation adjustment is to align the front pair relative to the rear pair using the three front lens-set collimation screws.  So, the actual process is similar in principle to collimating an ordinary doublet, except for the more challenging lens cell adjustments on the NP101."

 

Basically what happens is that the front lens pair and the rear lens pair need to be aligned.  It's a tilt adjustment and only the tilt of the front pair (the objective) can be adjusted.  

 

If there were a set of screws that allowed the tilt to be adjusted, it would be more robust and less likely to shift collimation.  The jig I built, provides those screws. 

 

Jon


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#204 Jeff Morgan

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Posted 31 December 2020 - 10:49 AM

This thread might give you some insights:

 

https://www.cloudyni...778/?p=10461315


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#205 starcanoe

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Posted 31 December 2020 - 12:16 PM

 2 were not too challenging but the third was a several day head scratcher and worry until it finally cracked free before the head was to damaged to engage the Allen wrench. I

 

A trick I use anytime an allen wrench screw/bolt gives any appearance of not breaking loose easily. Use a layer or three of aluminum foil to take up any slack/space between the allen wrench and the sides of the hex hole in the screw/bolt...


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#206 25585

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Posted 01 January 2021 - 02:20 PM

This thread might give you some insights:

 

https://www.cloudyni...778/?p=10461315

Many thanks. It seems then that if the front objective lenses are both perfectly aligned, as a perfect set-up by themselves, as for a standard doublet (can that be independently proven?), anything amiss with the rear lenses has to be corrected by compromising the front lenses. 

 

Do any other makes of Petzval have easier collimation adjustments to either or both sets of lenses front and back? 




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