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Vyper 14 Chassis

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#1 Eddgie

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Posted 28 May 2020 - 08:57 PM

Been meaning to post on this.

 

Another CN member that I PMed with purchased from Ultimate Night Vision and Ultimate told him that they built up his system using the Vyper 14 chassis rather than the PVS-14 chassis.

 

Now the Vyper 14  chassis has been around a bit but I was not really familiar with it, so I did some research.

 

As it turns out, the Vyper chassis is a composite chassis that takes the place of the PVS-14 chassis (the part that holds the tube). It still uses the PVS-14 objective and still used the PVS-14 power supply and eyepiece, but the primary difference is that unlike the PVS-14, the objective on the Vyper chassis is removable without having to take the device completely apart.  There is a threaded ring (Burk ring) that secures the PVS-14 objective and this makes it possible to essentially just screw the objective off.

 

This would make it possible to make an adapter so that the Vyper 14 could be used at prime focus!

 

Now the other good news is that you can buy the chassis and retro-fit it to a PVS-14.  I think the price is something like $260.  Since you use the same power supply, objective and the same eyepiece, it would be a pretty straightforward teardown and rebuild. 

 

So, this may be a great upgrade to PVS-14 owners that want to have the option of doing prime focus!

 

https://www.ultimate...BwaAnhTEALw_wcB


Edited by Eddgie, 28 May 2020 - 08:59 PM.

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#2 gatorengineer

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Posted 29 May 2020 - 09:15 PM

Do you know what the threads are for a pvs 14 lens?  Maybe a group order to a custom adapter for cameras lenses



#3 Eddgie

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Posted 30 May 2020 - 10:14 AM

The PVS-14 is held in place by the objective locking ring that mounts inside the PVS-14 chassis.

 

You an see it in this video (thanks to Cnoct).

 

https://www.youtube....h?v=FTwvNjY8210

 

With the Vyper, it appears that the Burk ring acts as the infinity focus lock ring on the PVS-14 and has a part that extends down into the chassis and somehow captures the lens from the front.

 

What one would need to know thin is the thread on the outside of the Vyper 14 housing where the Burk ring mounts. Is all that would be required would be a female thread adapter to mount on to the threads the Burk ring mounts to, and the other side could be T2 female. I would think that this kind of adapter could be made by RAF Camera for $40 or $50.



#4 Wildetelescope

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Posted 30 May 2020 - 10:21 AM

The PVS-14 is held in place by the objective locking ring that mounts inside the PVS-14 chassis.

You an see it in this video (thanks to Cnoct).

https://www.youtube....h?v=FTwvNjY8210

With the Vyper, it appears that the Burk ring acts as the infinity focus lock ring on the PVS-14 and has a part that extends down into the chassis and somehow captures the lens from the front.

What one would need to know thin is the thread on the outside of the Vyper 14 housing where the Burk ring mounts. Is all that would be required would be a female thread adapter to mount on to the threads the Burk ring mounts to, and the other side could be T2 female. I would think that this kind of adapter could be made by RAF Camera for $40 or $50.


I will investigate.
Jmd

#5 cnoct

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Posted 01 June 2020 - 07:54 AM

It's great you brought this up Eddgie. 
 
Yes, if one is going to use a PVS-14 for both prime and afocal, these Photonis upper housings are slightly more convenient that the mil-standard upper. I say slightly because once when switching between prime and afocal one will be more inclined to just leave the objective without any sort retention whether that be the internal lock ring on the standard upper or the Burke ring on the Photonis uppers. 
 
If one just wants doesn't need the dual sided mounting points, the Vyper C Upper is the most cost effective. Not a whole lot more than what one could sell their mil-standard upper for.

Having guided a number of PVS-14 users in trying to adapt their PVS-14 for prime focus use, the biggest issues hasn't been the lens retention nor access to and removal of the retention ring. The biggest issue, an insurmountable one for most has been the nearly 40mm back focus requirement. It's not just that the tube is inset to deeply (10mm more that c-mount), it's that the battery cap extends so far forward that it effectively sets the focal plane beyond what most can reasonably overcome. There are cases were all that's been required was a change in focuser. No doubt there there are creative ways to over come this but it's an issue to be aware of and that regardless of the upper housing.

As an aside to this, the infinity stop is actually a more suitable mount point for adapting any PVS-14 upper that one that threads in the place of the objective, whether one removess the infinity stop ring and threads on an adapter or clamps one to the ring, it's the perfect mount point.

Here a PVS-14 adapted for prime using a bodged adapter created with scap parts from a 1.25" eyepiece and a PVS-5a objective. The lens elements from the PVS-5a have been removed, just the threaded sleeve remains, the threads are the same as on the PVS-14 objective.

PVS-14 Night Vision Astronomy 2.JPG

PVS-14 Night Vision Astronomy.JPG

PVS-14 Night Vision Astronomy 3.JPG

#6 a__l

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Posted 01 June 2020 - 05:12 PM

Why c-mount 40-10 = 30 mm? This standard require about 17.5 mm including the path inside the sensor to the photocathode (~ 3-4 mm)? This is probably some other distance?



#7 a__l

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Posted 02 June 2020 - 07:22 AM

Curious. 0.97 "= 24.6 mm
I have a Fujinon-CF75HA-1, for it a bronze ring is slightly larger than 7 mm, about the same depth of the sensor surface + ~ 3 mm of the photocathode. Total 17.5 mm.
At 24.6 mm, I cannot sharpen this lens to infinity.

Probably for Paracorr-1 for prime focus (using the technology that I did), too. There is an extension of only 18 mm.


Edited by a__l, 02 June 2020 - 07:34 AM.


#8 cnoct

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Posted 02 June 2020 - 11:33 AM

On the PVS-14, the flange to physical image plane is ~ 1.35.

 

If one where to need to take into account the protruding battery cap, add an additional  ~0.52" to the ~ 1.35 flange to physical image plane. So the physical image plane can be as deep as ~ 1.87", that's significant.

 

On the c-mount NVD Micro Monocular, the flange to physical image plane is ~ 0.75".

 

If one where to need to take into account the protruding battery cap, add an additional ~ 0.22" to that of the ~ 0.75" flange to physical image plane. The depth of the physical image plane for the Micro is more manageable with the image plane recessed a maximum of ~ 0.97".



#9 a__l

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Posted 02 June 2020 - 06:18 PM

Even if use NVD Micro Monocular with 0.75 "(19 mm), probably can’t focus on my Fujinon for infinity (or very close to the limit). With paracorr-1, the situation is simpler, there is only more or less coma correction ....



#10 cnoct

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Posted 03 June 2020 - 05:39 AM

There are tolerances and what is listed are approximations, they are to convey the magnitude of what may be involved in adapting a PVS-14 whether it is with a mil-standard upper or one such as the Vyper or Hyper etc... 

 

The physical distance to the image plane and the focal distance are not necessarily the same, a photon/s interactions between the flange to focal plane determines the focal distance. The glass input window reduces the focal distance from that of the physical flange to focal plane.

 

The measurements on both the PVS-14  and NVD Micro are with an L3 tube, the physical distance from flange to focal plane is not the focal distance for the sample tube, it is the physical distance only. To be nearly dead on the focal distance drop ~ 0.05" - 0.07" to account for the glass of the input window. Focal distance varies from tube to tube and manufacturer to manufacturer. Had I used an Elbit tube, not only would the physical flange to focal plane be slightly different so would the focal distance.

 

Tube manufacturer do provide the focal distance when requested and as standard on certain systems. This is most frequently done on fixed focus systems or systems with limited adjustment, ones where the tubes are shimmed to the focal distance. The focal distance is typically denoted on the tube boot or ident plate/label. I've seen variations from 3.73mm to 4.70mm. Tubes for systems with critical focal distance, particularly fixed focus systems, have the focal distance engraved on them. 

 

The rational for presenting the physical distance, flange to focal plane versus the focal distance, was for simplicity.  Everyone with a PVS-14 can easily measure the physical distance, it's so very close to the focal distance and that it should be as close as needed. The large back focus required, in adapting a PVS-14, is significant to considerations in adapting a PVS-14 for prime. It's not a simple endeavor, it's not limited to the telescope interface. I think it's great Eddgie brought it up as those up to it, will likely find these uppers to be far better suited than the mil-standard.  

 

I've seen endless frustration in regards to back focus with NV systems, on systems featuring minimal flange to focal plane distances, those ideally suited to prime, now double the back focus requirement. It's possible, I and other have done it. 

 

Here's a visual representation: 

 

Flange to Focal Plane for PVS-14 and NVD Micro.jpg

 

 

 

 

 

 

 

 

 

 



#11 a__l

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Posted 03 June 2020 - 07:24 AM

The physical distance to the image plane and the focal distance are not necessarily the same, a photon/s interactions between the flange to focal plane determines the focal distance. The glass input window reduces the focal distance from that of the physical flange to focal plane.

 

 

Yes I know that. Physical distance is greater. Lens focus it is necessary to check in practice along with NV.

https://www.asu-nvg....0GSpecSheet.pdf

 

It looks like> 6 mm

 

My distance to the sensor glass is about 14.5 mm. From practical measurements and fit distance. It looks like 0.97" (24.6 mm) looks a bit big for the c-mount standard (if this is the physical distance to the photocathode).


Edited by a__l, 03 June 2020 - 07:38 AM.


#12 gatorengineer

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Posted 03 June 2020 - 10:12 AM

trying to figure out how this applies to a Vyper Chasis and drawing a blank....



#13 cnoct

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Posted 03 June 2020 - 10:30 AM

The significant back focus issue that accompany the PVS-14, it doesn't change with the Vyper housing the back focus issue exist. The PVS-14 has always been problematic, changing the upper to a design that enables external removal of the objective does little to address what has always been the hurdle for those looking to do prime with a PVS-14. 

 

That's how the mil-standard and Vyper upper housing are related, they both present the same back focus issue, the focal plane is inset deeply, especially when including the protruding battery cap. The Vyper retains that same issue.  



#14 gatorengineer

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Posted 03 June 2020 - 11:29 AM

Thanks for clarifying.



#15 Wildetelescope

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Posted 03 June 2020 - 01:17 PM

The significant back focus issue that accompany the PVS-14, it doesn't change with the Vyper housing the back focus issue exist. The PVS-14 has always been problematic, changing the upper to a design that enables external removal of the objective does little to address what has always been the hurdle for those looking to do prime with a PVS-14. 

 

That's how the mil-standard and Vyper upper housing are related, they both present the same back focus issue, the focal plane is inset deeply, especially when including the protruding battery cap. The Vyper retains that same issue.  

 

So to beat the dead horse enough to make sure I understand, for the PVS 14 housing has the phosphor screen is set farther back from the opening than you typically see in other configurations, meaning that you have to move your focuser further in to come to focus when not used afocally.  And this is made even worse because the battery housing sticks out so far. Correct?   I can see how this would be a horrible issue for some scopes.  Do folks find this to be a problem for SCT or maks, out of curiosity?   Another possibility would be to use the system without a diagonal, which has its own issues, but would mitigate the backfocus issue.  Or use of a prism diagonal.   Of course the simplest approach if you really are set on doing prime focus NV is to get the right housing for the job.  For my part, I am interested in primarily afocal observing, and I ended up with the Vyper housing by chance.  But this is certainly an interesting discussion  and I am learning quite a lot from it. 


Edited by Wildetelescope, 03 June 2020 - 01:32 PM.


#16 Eddgie

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Posted 03 June 2020 - 01:39 PM

 

 

That's how the mil-standard and Vyper upper housing are related, they both present the same back focus issue, the focal plane is inset deeply, especially when including the protruding battery cap. The Vyper retains that same issue.  

This is what I was curious about.   The pictures do not really make it clear as to whether the Burk ring removal buys any reduction in the anount of distance from the mounting flange to the focal plane. 

 

Still, maybe for imaging Newtonians or refractors with 2" diagonal, this might be an option.

 

I had considered getting a power supply and Vyper chassis to convert one of my Mod 3s but knowing this, I guess I will pass. 



#17 gatorengineer

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Posted 03 June 2020 - 08:06 PM

Spoke with TNVC tonight Vic, he checked with two of his builders and they didnt think but werent sure that Vyper was able to have the lens taken off without tearing into the unit.  Looks like we need someone to take one for the team and find out.

 

Also and interestingly, Vic indicated that Photonis tubes were hard to come by, due to the current situation in the world today.  L3 Tubes he said he is moving alot of.  Getting a quote for a system with a Spec'd tube and will post what he is proposing for specs when recieved....



#18 cnoct

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Posted 04 June 2020 - 04:49 AM

Spoke with TNVC tonight Vic, he checked with two of his builders and they didnt think but werent sure that Vyper was able to have the lens taken off without tearing into the unit.  Looks like we need someone to take one for the team and find out.


That's exactly why the Burke ring exists.

The Burke ring replaces the internal retention ring with an external one so that the entire system needn't be torn down to remove or replace the objective. In its retention method, the ring essentially functions as a circlip.

It might be worth mentioning that if all seals are good, installing the objective, on what is otherwise a sealed system, can cause the system to be positively pressurized which can cause the both the eyepiece and objective to drift slightly. Not a big deal but can be annoying, easy fix is to just keep the purge port vented or vented until best working focus is achieved.

#19 cnoct

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Posted 04 June 2020 - 04:59 AM

This is what I was curious about.   The pictures do not really make it clear as to whether the Burk ring removal buys any reduction in the anount of distance from the mounting flange to the focal plane. 
 
Still, maybe for imaging Newtonians or refractors with 2" diagonal, this might be an option.
 
I had considered getting a power supply and Vyper chassis to convert one of my Mod 3s but knowing this, I guess I will pass.

And that curiosity is what may serve to stimulate creative adaptations for NV systems, not just PVS-14's. 
 
Adapting a PVS-14 to prime is most definitely doable, with my dobs focuser rack all the way in, I can just achieve focus. That's with the stock focuser and a lipless 2" to 1.25" eyepiece adapter. With not much more than an adapter and low profile focuser, a PVS-14 can be adapted for prime.  
 
I think you would really like the PVS-14, regardless if you adapt it or not. The gain pot is so much better on it than on the mod-3, like a fine audio knob on a high fidelity sound system. There also something about the feel of a 14, it just fits and feels good in the hand.

FWIW: For a toolless option to the Burke Ring and for those with existing PVS-14's not wanting to buy an entire upper, the D-Collor from Knights Armament might be the solution... https://www.knightar...p-shoe-set-copy



#20 gatorengineer

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Posted 04 June 2020 - 07:03 AM

that D collar looks like the ultimate solution for PVS-14 users.....

 

What advantage does Vyper have over PVS-14, other than the lens issues?



#21 Wildetelescope

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Posted 04 June 2020 - 08:20 AM

That's exactly why the Burke ring exists.

The Burke ring replaces the internal retention ring with an external one so that the entire system needn't be torn down to remove or replace the objective. In its retention method, the ring essentially functions as a circlip.

It might be worth mentioning that if all seals are good, installing the objective, on what is otherwise a sealed system, can cause the system to be positively pressurized which can cause the both the eyepiece and objective to drift slightly. Not a big deal but can be annoying, easy fix is to just keep the purge port vented or vented until best working focus is achieved.

This raises an interesting question for a newbie.  What is the purpose of the purge port?  Is the interior supposed to be purged with an inert gas?   If you break the seals by taking the system apart, do you need to re purge?  Or is it simply there to alleviate the pressure build up that you mention.  

 

Thanks!

JMD



#22 cnoct

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Posted 04 June 2020 - 08:37 AM

that D collar looks like the ultimate solution for PVS-14 users.....


Yes, got to agree with you.


What advantage does Vyper have over PVS-14, other than the lens issues?


For me it would be the fitment for the weapons interface shoe that's part of the obverse mounting kit. I don't care for the floating shoe for helmet mounting but the weapons interface shoe doesn't fit properly with the mil-standard upper. So for me this would be only other advantage.

I don't like the bulk of the Vyper or Hyper, while physically they are not much larger, in the hand they feel bulky and lack the ergonomics of the mil-standard upper. Some may not find them so, just what I've found.

#23 Wildetelescope

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Posted 04 June 2020 - 08:37 AM

that D collar looks like the ultimate solution for PVS-14 users.....

 

What advantage does Vyper have over PVS-14, other than the lens issues?

The argument for the Vyper, if you read the advertising, is that 1 it is easier to take apart and put together, 2. it has a couple more places to attach things to and or to attach the PVS 14 to other things(like rifles, etc...). and 3. The enclosure is made of a glass fiber filled Ultem composite, which is durable as anything.   It is important to keep in mind that these things are really designed and marketed for tactical use.    The assumption is you might need to repair/replace things in the field and the Vyper chassis should make that easier, or so the claim goes.  I will defer to those who have actually used these things in tactical situations speak to the veracity of advertising:-).  In the commercial realm, hunting is probably top of the list, and that might be really where something like the Vyper is of interest.  I doubt anyone was thinking about sticking one of these on a telescope when they were designing the chassis.  For that you have to go to a Collins I3 eyepiece. 

 

JMD



#24 cnoct

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Posted 04 June 2020 - 08:57 AM

This raises an interesting question for a newbie.  What is the purpose of the purge port?  Is the interior supposed to be purged with an inert gas?   If you break the seals by taking the system apart, do you need to re purge?  Or is it simply there to alleviate the pressure build up that you mention.  
 
Thanks!
JMD


Yea no, the purge port is for purging.

I suggest, as a way to eliminate focus drift from the internal atmosphere being positively pressurized, above the purged pressure, that opening the purge port will eliminate this. This is only relevant if your removing and installing the objective on a sealed, built, PVS-14, otherwise the purge port is for purging. 

Yes, When bought new, from a vendor that builds to mil-standards, the system should be purged with an inert gas.

 

Here's a great build video by Ultimate Night Vision that shows the purging process: https://youtu.be/nzzwWOuhhK0?t=357

 

Should you purge or have it purged if you lose the purge for any number of reasons, that's up to the user/owner. Not sure how many are willing to send their system in every 6 months or so to have it vacuum tested and purged. I purge on my personal systems that are under heavy regular outdoor use. I'm not exposing my systems to thermal shock and dramatic shifts in humidity either. 

 

Don't know of many c-mount system that are purged, can say for certain the Collins I3 never was, don't think it's been an issue. The NVD Micro, used in great numbers by many NV astronomer, isn't typically purged though it still incorporated the port. 


Edited by cnoct, 04 June 2020 - 11:31 AM.


#25 Wildetelescope

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Posted 04 June 2020 - 10:43 AM

Thanks! Appreciate the information.

Jmd


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