36 replies to this topic

[GGK]

I'm considering adding a night vision device for use with my existing scopes and I've read through most of the "Best Of" topics, but much of the material seems dated.

 

I'd like to know the latest thinking on Prime vs. Afocal for a new purchase.

 

I saw that the AB Night Vision website states "12/23/2022: The MOD-3 is a legacy system that is being phased out.", so I'm guessing that a Mod-3 C-mount is no longer an option.  I also looked for the NVDepot Micro that I saw mentioned in older posts, but couldn't find any availability of that either.

 

Is C-mount for prime use basically a non-starter today, or am I just not searching correctly?

 

PVS-14's are everywhere, so maybe Afocal is the best choice today. Is Prime possible with any of the available PVS-14s?

 

Gary

 

 

[Mazerski]

AB Nightvision: Adam Barker introduces himself (in Post #12) in this thread from May 2024 and states the C Mount Mod3 is coming back

 

https://www.cloudyni...d#entry13440206

 

Some NV users are very clever and have made their own adapters or had RAF Camera make adapters… but a c-mount nosepiece (generally speaking) is more flexible than a PVS14 in use via hand-held and with a scope (I.e. a filter wheel). 

Edited by Mazerski, 12 August 2024 - 12:50 PM.

[Souldrop]

MOD3 was replaced by a c mount version of the rvm-14.

If I was buying new today it would be a tough call. C mount is awesome since you can use camera lenses as mini telescopes. Unfortunately unless you find an ENVIS objective a c mount nvd is more limited in some ways since it may be harder to source parts to use afocally.

[shohin]

ENVIS lenses can still be had if you're willing to do a little horse trading. For example, at this moment there are five M703E ENVIS monoculars for sale on ebay, each complete with its original objective lens. They pop up on ebay quite regularly. Buy one, transfer the lens to your RVM/MOD3C/prime-converted PVS-14, then resell the remaining parts. Or find a standard C-mount lens, like a Computar v2513 or similar, put it back on the M703, and use it for camping or navigating around your dark site or whatever.

[sixela]

There are cheap Pentax/Ricoh 25mm f/1.4 C-mount lenses that really do work quite well as a replacement (for some time I used them on an OVNI-M before I converted a couple of PVS-14 objectives for use on an OVNI-M.) Even more so if the effective f/ratio of the stack at the photocathode is slightly more than f/1.4.

You just need to watch out to get the ‘1” sensor’ version and not the ‘2/3” sensor’ version.

This is a link to the new version:
https://www.ricoh-io...VGA-Lenses.html — the link also mentions the old Pentax part number (C22525KP).

But you can usually find them for $35-50 on EBay (especially if older and Pentax- or Cosmicar branded), often still in the box unused.

Bonus: they have broadband coatings so they’re excellent for use on L3 unfilmed tubes that still respond fairly well to blue (and of course Photonis Gen 2+ tubes too) when you really don’t want to suppress transmission in blue light (while some dedicated NVD objectives have worse transmission below 500 nm).

Edited by sixela, 13 August 2024 - 02:26 AM.

[John Vogt]

Hi sixela,

 

Does this lens meet the 1" sensor criteria:

 

Brand NEW Cosmicar Pentax (Ricoh FL-BC2514D-VG) 25mm f/1.4 VGA CCTV Lens

 

Thanks!

John

[sixela]

The text is a bit confusing -- the part number is from Ricoh, Cosmicar never used that part number. It *is* the Ricoh part number for the 1" version, though.

Pentax/Cosmicar C22525KP aka Pentax B2514D aka Ricoh FL-BC2514D-VG 25mm f/1.4

The 2/3" version usually contains "C2514-M" (or these days "CC2514-5M") in the part number (unless it's an old Cosmicar, which has part number C32501KP or C32500KP IIRC).

But given the confused description (is it a Cosmicar branded one? Pentax/Cosmicar branded one? Pentax branded one? Ricoh branded one? What's on the box?) God knows whether the lens actually matches the description.

It's usually easy to see from photos. Especially on photos from the back, the lens in the 2/3" is a lot smaller.

This is the 2/3" version:



And this is the 1" version:


But man, EBay can be weird:
https://www.ebay.com...67691985?_ul=MX

It's got the Ricoh part number for the 1" 25mm f/1.4. The "photo" is not a photo but a catalogue image for the 12.5mm, and in the description they say it's a C21211KP, which is indeed the (much older) 1" 12.5mm Cosmicar part number...

So go figure what it is...the left and right hand can't even agree on what focal length it has. And with no actual photo, it's anyone's guess. And who knows, it could yet be a 2/3" sensor version too.

At least this one at least has pictures of the right box ;-) -- and it is indeed probably new given it has Ricoh branding.
https://www.ebay.com...490.c101224.m-1

Edited by sixela, 13 August 2024 - 06:49 PM.

[John Vogt]

Thanks for the additional info.

 

The only picture is a side view.

Further down the page the description indicates a Ricoh C21211KP and "compatible with

cameras from 1/2" to 1", if that means anything.

[GGK]

MOD3 was replaced by a c mount version of the rvm-14.

If I was buying new today it would be a tough call. C mount is awesome since you can use camera lenses as mini telescopes. Unfortunately unless you find an ENVIS objective a c mount nvd is more limited in some ways since it may be harder to source parts to use afocally.

 

ENVIS lenses can still be had if you're willing to do a little horse trading. For example, at this moment there are five M703E ENVIS monoculars for sale on ebay, each complete with its original objective lens. They pop up on ebay quite regularly. Buy one, transfer the lens to your RVM/MOD3C/prime-converted PVS-14, then resell the remaining parts. Or find a standard C-mount lens, like a Computar v2513 or similar, put it back on the M703, and use it for camping or navigating around your dark site or whatever.

Thanks to both of you for the replies.

 

I read through the AB Night Vision website about the RVM-14 c-mount and I looked at pictures of the Envis unit on EBay to see how the Envis lens can be removed and attached to the RVM-14.

 

Now for the dumb questions -- 

 

First note that I have an understanding of the components needed to use a PVS-14 unit in A-focal mode with a TV eyepiece and can picture how that works. 

 

I can't picture, though, how the Envis lens differs from the PVS-14 lens functionally (attaching to the telescope or eyepiece), and how the Envis lens is used in prime mode (and why it works when PVS-14 doesn't). 

 

For prime, do you just attach a 2-inch nosepiece to the Envis lens and stick it into the diagonal?  If yes, why doesn't that work with the PVS-14?   In A-focal mode, do they both use the same lens to eyepiece adapter (like the Tele Vue one)

 

I've read a lot about this, but all the info starts a bit past this basic understanding and I'm just having trouble getting this pictured in my head.

 

Thanks.  Gary

[Mazerski]

Gary,

 

On the Mod3 and PVS7 — mine are from 2017, both are c-mount and both came with the ENVIS lens that apparently are no longer made. The C-mount ENVIS unscrews (you physically remove it as it is not used in Prime Mode) and then you screw in a c-mount to 1.25” or c-mount to 2” adapter to slide in focuser or filter wheel. 
 

There’s a slew of pages here and some by me and I’ll try to look up one that has photos.

 

 

[Mazerski]

Go here:

https://www.cloudyni...i#entry11284974
 

Post #11 — you see the ENVIS lens is removed and what you are looking at are the c-mount nosepiece with ScopeStuff 1.25” and 2” adapters that enable device to slide in focuser and filter wheel.

 

Post #12 — shows a Nikon Nikkor lens for hand-held mode with the Nikon F to C adapter.

Edited by Mazerski, 13 August 2024 - 09:34 PM.

[sixela]

Thanks for the additional info.
 
The only picture is a side view.
Further down the page the description indicates a Ricoh C21211KP and "compatible with
cameras from 1/2" to 1", if that means anything.

Seems to be the one I linked to. That is indeed a 1" sensor model, but it is the part number for the *12.5* mm lens.

[sixela]

Thanks to both of you for the replies.
I can't picture, though, how the Envis lens differs from the PVS-14 lens functionally

Functionally, it's not different. Mechanically, it is different because the thread used is more narrow.

 
 

For prime, do you just attach a 2-inch nosepiece to the Envis lens and stick it into the diagonal?

No, in prime mode you remove the ENVIS lens and use the telescope as the NVD objective.

 

If yes, why doesn't that work with the PVS-14?

It does. But they're not designed to be used without objective, and in some cases the vendor will consider the warranty voided if you remove the NVD objective. You also (unless you let the vendor do it) need to remove the close focus stop ring which is inside to be able to remove the objective, which means disassembling the PVS-14 (and really you also want the tool to remove the ring). Not for the faint of heart, given the price of these items (I did it but I have an OVNI-M so if I mess up I'm not without an NVD ;-) ).

The PVS-14 also has the NVD tube recessed quite far into the PVS-14. Let's just say that you need the focal plane thrown out 57 mm above the fully rackedin focuser not to have any trouble using a PVS-14 in prime mode. That's common on smaller "photo-Newtons" but not on larger Dobs. On larger Dobs you might have to use a Paracorr (without tunable top) to throw out the focal plane enough to get to focus without the PVS-14 hitting the fully racked in focuser.

All that being said, with a couple of RAF Camera adapters and adapters on a Paracorr (or an ES HR-CC) you can make a PVS-14 work in prime mode (and even barlowed prime) even on a large Dob. You'll need to figure out the correct spacer rings for the different setups, though. You most often won't be able to use some other coma correctors, though (and that sadly includes the Nexus, you'll be stuck using an afocal setup instead of Nexus+prime for that magnification).

What will not work is attaching C-mount objectives to a PVS-14. The C-mount flange distance is just way, way, way shorter than the distance the PVS-14 tube is recessed in a PVS-14.

Edited by sixela, 14 August 2024 - 03:16 AM.

[shohin]

Here's another pic that may help.

 

  - On the left, from the top, M703E ENVIS body, MOD3C body.

 

  - On the right, from the top, Computar V2513 lens, M703E ENVIS lens, 1.25" eyepiece adapter.

 

Everything is C-mount. All attachments work with either body (and presumably would also work with an RVM-C).

 

For prime focus, use the eyepiece adapter. The ENVIS lens is not needed. 2" eyepiece adapters are also available, as Mazerski mentioned

.

For afocal with the TeleVue kit, use the ENVIS lens. The ENVIS lens is identical to the PVS-14 lens except for the mounting interface. In stock form, the PVS-14 lens locked to the body and cannot be field stripped, precluding prime focus use.

 

Note that afocal can also be done with a commercial C-mount lens like the Computar, but you're on your own figuring out which adapters you need to attach it to your eyepiece.

 

Attached Thumbnails

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[bobhen]

Thanks to both of you for the replies.

 

I read through the AB Night Vision website about the RVM-14 c-mount and I looked at pictures of the Envis unit on EBay to see how the Envis lens can be removed and attached to the RVM-14.

 

Now for the dumb questions -- 

 

First note that I have an understanding of the components needed to use a PVS-14 unit in A-focal mode with a TV eyepiece and can picture how that works. 

 

I can't picture, though, how the Envis lens differs from the PVS-14 lens functionally (attaching to the telescope or eyepiece), and how the Envis lens is used in prime mode (and why it works when PVS-14 doesn't). 

 

For prime, do you just attach a 2-inch nosepiece to the Envis lens and stick it into the diagonal?  If yes, why doesn't that work with the PVS-14?   In A-focal mode, do they both use the same lens to eyepiece adapter (like the Tele Vue one)

 

I've read a lot about this, but all the info starts a bit past this basic understanding and I'm just having trouble getting this pictured in my head.

 

Thanks.  Gary

I use Prime Focus in my 8-year-old NVD Micro. Putting a system together is easy. To give you an idea below is how I set up my refractors and C8 with the intensifier.

 

From left to right…

 

1. The refractor optical tube, or any OTA
2. My GSO 2” focuser, or any 2” focuser
3. An Astro-Physics 2” diagonal (these have short light paths)
4. Optional: An Antares 2” .7 reducer (the reducer screws onto the bottom of the 2” to 1.25” adapter that comes with most diagonals or can be bought separately)
5. The 2” to 1.25 adapter that comes with most 2” diagonals
6. 1.25” filter (Ha or IR Pass Filters) screwed onto the C-mount adapter. 6 or 7nm Ha filters are popular, 685 pass filters are popular in heavy light pollution
7. C-mount to 1.25” adapter (screwed onto the nose of the intensifier) Unscrew any lens that comes with the intensifier and screw on this adapter
6. The NVD Micro Intensifier

 

Bob

Attached Thumbnails

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Edited by bobhen, 14 August 2024 - 07:14 AM.

[GGK]

 

 

 

 

Thank you - you're replies helped me picture and understand how this works.

 

A couple of follow-up questions:

 

1. I want to be sure I understand correctly on this one for A-focal - is it correct that both the Envis lens and the PVS-14 lens have the same threads to attach the Tele Vue NV lens-to-eyepiece adapter for A-focal use?

 

2. If I buy the AB Night Vision RVM-14 C-mount, does it come with a lens of some kind attached, or does it simply end with the C-mount flange?  I'm still a bit fuzzy on understanding what the PVS-14 lens physically looks like and why it doesn't come with threads to screw into the C-mount similar to the Envis lens.

 

3. To have a system for both prime focus and A-focal use, what I think is that I can purchase the RVM-14 C and unscrew any lens that is attached, then

- buy a C-mount to 2' or 1-1/4 barrel adapter to attach to the NVD for prime focus

- buy a used Envis system and transfer the Envis lens lens to the RVM-14, for hand held. I'd also need an Envis lens-to-filter adapter to attach an Ha filter when wanted.

- same as above, but add the Tele Vue Envis / PVS-14 lens-to-eyepiece adapter for A-focal and attach any filters to the eyepiece.

 

Do you see anything incorrect in point 3 above or is there a better/easier way?  

 

Thanks, again.  Gary

[Mazerski]

To keep it simple, let’s call the ENVIS lens itself the “objective”. The objective unscrews from a c-mount nosepiece. The objective on a PVS14 does not - it’s all one assembly. Now some NV users have asked the vendor to remove a retaining ring (or whatever it’s called) such that the objective can be removed. I don’t know if doing this voids the warranty. 
 

Unknown to me if buying a new c-mount device what type of lens would be supplied, if any as the ENVIS is no longer available. FYI — back in 2017 the ENVIS cost $100. I find 1x viewing rather boring, so I sold 2 of them in 2019 for $400 each due to demand. 
 

I don't use in afocal-mode, but my understanding is that if you have a c-mount and can find the ENVIS lens, the threads are the same as the PVS14 lens threads so the device could then be used in afocal-mode. 

Edited by Mazerski, 14 August 2024 - 11:24 AM.

[shohin]

It's also my understanding that the ENVIS and PVS-14 (and PVS-7) lenses all have the same filter threads.

 

Whether or not you get a lens with your RVM-C will depend on the dealer you buy it from. Most likely it will be only the body. My MOD3C from TNVC did not come with a lens.

 

To see the difference in lens mounting interfaces, compare the PVS-14 lens in this link to the picture of the ENVIS lens I posted above.

https://tnvc.com/sho...-lens-assembly/

 

And just fyi, here's an example of afocal with a commercial C-mount lens.

https://www.cloudyni...tar-v2513-lens/

[sixela]

1. I want to be sure I understand correctly on this one for A-focal - is it correct that both the Envis lens and the PVS-14 lens have the same threads to attach the Tele Vue NV lens-to-eyepiece adapter for A-focal use?

Yes. For fairly arcane legal reasons it's a thread with pitch and diameter based on inches (1.2", 32 tpi) but really closer to (metric) ISO M30.3x0.8.

Not sure what an RVM-14 C-mount would ship with. If you don't need something with the same specs/performance/f-ratio as the ENVIS there are lots of 25mm C-mount lenses to try out (cfr. the Pentax above). Yes, it's f/1.4 and not f/1.2, the edge aberrations at f/1.4 are slightly worse (but different and slightly less funky transitioning to the edge), and there is a tad more vignetting (the PVS-14 optics go very close to the photocathode window, closer than any C-mount lens could go), but it's definitely more than usable. In fact on my OVNI-M before I got converted PVS-14 optics I used it in preference to the (different) OVNI-M front lens that I got.

I have tons of other 25mm C-mount lenses, inclduing a Computar f/1.3 which I like a lot less than the Pentax (it's really only f/1.3 in the middle, with a lot more vignetting starting fairly early, and more aberrations). Some fun ones too that I do use occasionally (a Schneider when I wnat to go down to effective f/ratios of f/0.95 in the middle of the FoV, vignetting at the edges be darned).

The Pentax has a standard M27x0.5 filter thread, it's not that hard to connect it to eyepieces.

Edited by sixela, 14 August 2024 - 05:28 PM.

[John Vogt]

I purchased the Ricoh lens sixela linked.
Although I use an Envis with my L3 umfilmed tube, I’m curious to see if the Ricoh does better at the blue end of the spectrum with the Broadband coatings sixela mentioned.

[WheezyGod]

I had thought the RVM came with a detachable lens that was similar in quality if not better than a PVS-14 standard lens considering that there are higher priced lens options with the RVM. If it does (sounds like it doesn’t though), then a RVM would probably be the best choice for astronomy if it’s available most places where a PVS-14 is.

[sixela]

There’s a RVM version with PVS-14 objective IIRC. But I don’t know what the C-mount version comes with.

[Souldrop]

Yeah, the standard rvm that shares objectives with the pvs-14 tends to come with “premium” lighter weight objectives (last I looked into it the optical was worse than the standard “carson” objective)

[sixela]

RPO 3.0 ? That's not too bad, and better than most C-mount lenses you can get (with the exception of the ENVIS lens).

[Souldrop]

Yeah, but its vendor/builder specific. A lot of vendors seem to be offering rvm housings with rpo optics as a tanto alternative to appeal to the lightweight crowd using them helmet mounted.

Some just use standard objectives. If going for complete rvm unit from a vendor/builder it’s definitely worth double checking what objective is being used.


As far as the default objective for a c mount I have not heard of any replacements. I would strongly assume that it would be like the mod-3 c mount and not come with an objective.