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Camera lenses for c-mount MOD3

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#1 NikhilJoshi

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Posted 22 April 2018 - 03:36 PM

I’ve ordered a c-mount MOD3 from TNVC for prime focus observing. I’m looking at cctv lenses for low power observing without a telescope. Looks like a 25mm cctv lens will provide 1x power - any preferred brand of cctv lens or other features to consider?

 

 I’ve also been looking at c-mount to Nikon adapters to use some of my camera lenses. Curious about how well they have worked for others. 

 

I also have a 2” 7nm H-alpha filter I was planning to use with purchased or 3d printed adapters if that factors into lens choice.

 

Not quite related, but if the unit arrives by mid June I’d like to take it on a trip to Hawaii (direct from-to Seattle). Obviously it’s a US state so I shouldn’t have any legal concerns but wonder if others have had issues with TSA when leaving the lower-48.

 

Thx,

 

-Nik


Edited by NikhilJoshi, 22 April 2018 - 03:52 PM.


#2 Jeff Morgan

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Posted 22 April 2018 - 10:43 PM

I have been using a C-mount to Canon adapter. Works well.

 

One issue is where to put the filter. It sounds like you are already have it figured out though. 2" over the front is easier.

 

The other thing that comes to mind - same issue bino users face - holding it steady for best viewing. Most of the weight is in the telephoto lens, so hand holding is somewhat odd.

 

I have tried a parallelogram mount and a Manfrotto Magic Arm. Did not like either. So I picked up a 2.6" diagonal mirror for cheap and will throw together something like the old Sky Window binocular mount. That was the most ergonomic bino rig I ever used, though it does have a mirror-reversed image.



#3 Eddgie

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Posted 22 April 2018 - 11:02 PM

I use a Nikon F to C mount and this works great.   The nice thing about the Nikon to C mount adapter is that it is deep enough that you can epoxy an empty color filter cell inside the adapter so that you can put your long pass or H-alpha filters inside.

 

Probably the best C mount CCTV lens is the Computar 25mm f/1.3 as shipped on the Night Vision Depot Micro Monocular.  I have one of these and it works well enough.   Not as sharp at the edge as the ENVIS, but otherwise fairly good.     I know that NV Depot used to sell these lenses, but I don't know if they still do, or if they will only use them on the complete Micro monocular.

 

I have a Fuji Optical 25mm f/1.4 that I actually got from a Night Vision shop on Ebay and while only a bit slower than the Computar it is otherwise very similar in performance and build quality to the Computar.

 

There may of course be others, but I bought a cheap CCTV 25mm f/1.8 or something like that from Ebay and it was horrible.   Avoid this lens or anything similar.   They simply are not very good.  

 

https://www.ebay.com...VoAAOSwkINa1uU~

 

This looks to be a genuine Cosmicar.  It says that it is f/1.4 on the post, but the aperture ring shows f/1.2.  It looks though like the objective is not quite big enough to be f/1.4, so this discrepancy seems important.

 

https://www.ebay.com...GEAAOSwqlha1P~c



#4 Eddgie

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Posted 22 April 2018 - 11:13 PM

Pricy, but this is probably a superb lens for C mount NVD...  Again, expensive, but super fast!

 

https://www.ebay.com...cgAAOSwcO1ajp7d

 

Or maybe this:

 

https://www.ebay.com...vMAAOSwnF9Y6q~r


Edited by Eddgie, 22 April 2018 - 11:18 PM.


#5 moshen

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Posted 22 April 2018 - 11:43 PM

I've not tried it since I have an Envis but the Computar is mentioned as second best. A few other members are working out the adapter solution to go from Computar threads to Televue Dioptrix so it may be easier to do afocal later with the Computar - but it looks like your scopes will do fine with prime focusing.

 

A lens that gives 3-5x power for hand held viewing is recommended as well. Envis guys can use the miitary afocal snap on 3x lens but without an Envis you'll be looking at a 75-150mm c-mount focal length lens.



#6 astronomia

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Posted 23 April 2018 - 01:38 AM

Nik, 

 

Like yourself I’m waiting for my MOD3 c-mount from TNVC.  I was able to get a Computar v2513 (25mm, f/1.3) which reportedly was used by vendors after the ENVIS became unavailable. I was unable to find that specific model on the Computar website. It may be that they are no longer in production. I found a new,surplus lens on the “bay” for about $78. Unfortunately, it appears that they sold out. I did a saved search for this specific lens and eventually received an email that the new/surplus was listed.

 

Regarding flying out to Hawaii with your NVD... From what I understand we’re limited to travel with them in the lower 48 only. Any vendor should be well versed in the precise regs. You may want to give Vic a call at TNVC for details on limitations on travel with the NVD.

 

Tom



#7 cnoct

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Posted 23 April 2018 - 05:20 AM

Not quite related, but if the unit arrives by mid June I’d like to take it on a trip to Hawaii (direct from-to Seattle). Obviously it’s a US state so I shouldn’t have any legal concerns but wonder if others have had issues with TSA when leaving the lower-48.

 
Quite right, no legal concerns whatsoever waytogo.gif 
 
Your GTG on all fronts, U.S. Department of State, TSA etc...
 
As with any electronic device, TSA may request that the device be turned on, though I've Neve experience this. Doesn't take much to plan for such, simple things like covering input with a pinhole cover, setting aperture to minimum, etc...
 
The X-ray screening is also not an issue. 
 
Enjoy your stay in the islands flowerred.gif
 
BTW: The U.S. Department of State defines United States as:
 
ITAR Part 120.13 United States.
 
United States, when used in the geographical sense, includes the several states, the Commonwealth of Puerto Rico, the insular possessions of the United States, the District of Columbia, the Commonwealth of the Northern Mariana Islands, any territory or possession of the United States, and any territory or possession over which the United States exercises any powers of administration, legislation, and jurisdiction.
 
Retrieved from https://www.pmddtc.s..._laws/itar.html


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#8 chemisted

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Posted 23 April 2018 - 07:39 AM

I have used a Nikon to C-mount adapter altered as Eddgie describes with great success.  I am especially fond of my 105 mm f/1.8 Nikkor.  With the H-alpha filter it gives an incredibly bright view of the large nebulous regions of the sky.  I got this lens on the cheap as it suffers from an incredibly stiff focusing ring - not a problem when you only need to focus once and then have it stay put!


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#9 Eddgie

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Posted 23 April 2018 - 08:12 AM

Yes, I also recommend a good SLR lens in the 180mm to 200mm range.

 

I was using a Tamron 80mm to 200mm zoom that is f/2.8 throughout its range a lot, but in the end, it proved to be a bit heavier than I wanted to use (it is for sale right now in the Classfied section) but I recently purchased a fixed focal length Nikon 180mm ED f/2.8.   This lens should be much lighter than the Tamron and I think ED glass will give sharper stars when running unfiltered, which I like to do when skies are a bit darker than my city location.

 

You can of course find other SLR lenses in the 28mm range and while these tend to be a lot larger than the CCTV lenses, they should work as well or maybe even better.   The CCTV lenses do have some field curvature because they are generally designed to work with very small chips where F/C is not a problem, but old SLR lenses would normally be well corrected for field curvature due to the 35mm frame size.

 

The great thing about old SLR lenses as they are sooooooo cheap (unless very fast).   The only negative is that they often do not focus red and blue at the same time, so long pass filter becomes more necessary to keep stars sharp.

 

Lots of options, but for afocal, the Computar or similar lenses should work well. 

 

If only someone would come up with a modification for the PVS-7 or PVS-14 objectives to allow them to go to C mount.  I took my PVS-7 objective out of the housing to see if it was something I could do myself but decided that it would require some machining to do, and is beyond what I can do myself. 



#10 Doug Culbertson

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Posted 23 April 2018 - 08:22 AM

I also use a Nikon lens with an F-C adapter. Mine is a Nikkor 135mm f/3.5 and I love it. In fact, it's become my most used piece of gear, with both the Mod-C and the PVS-7. These 135mm f/3.5 Nikons can be found on EBay all the time at very good prices.



#11 Jeff Morgan

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Posted 23 April 2018 - 09:09 AM

One of the beauties of telephoto lenses is the variety of focal lengths.

 

I was thinking that 50mm could be a very good framing for (most) individual constellations. This was one of the neat features of the Vixen 2.1 x 42 binoculars. 



#12 Eddgie

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Posted 23 April 2018 - 11:12 AM

Ok, I looked at my Ebay history and this is what I got.

 

I had purchased a lens called the NAV3 C mount from Nitesite on Ebay.    This is a C mount lens that looks kind of like the ENVIS, but is probably about f/1.3 or f/1.4.  The one I bought though had some slop in the focuser.   If you reversed focus, it you had to turn about 3/16th of an inch for it to start driving in the opposite direction.  It was not terrible, but I asked the seller to excange it, and he offered to substitute it with the Fuji and I thought the Fuji performed about the same, but with better mechanical finish.    The Fuji is very similar to the Computer differing only in being f/1.4 vs f/1.3 for the Computar.  Otherwise, it is mechanically very nice.

Here is a picture of the NAV 3 C mount:

 

NAV 3 C.jpg

 

Agian, this is the lens that the seller subed for the NAV 3.  This is a very nice lens.  Made in Japan and I think very similar to the Computar:

 

Fuji 25mm f 1.4.jpg

 

There is a catch though.   I spoke to the seller and he now has a minimum order of $500.   He is checking stock to see if he has either of these lenses or any ENVIS lenses gathering dust and he is going to contact me and let me know the inventory.

 

If he has any and there is sufficient interest, perhaps everyone that is interested can get together and come up with enough for the minimum order and work out re-distribution. 

 

Hope this helps.   Will post as soon as I hear back from Nightline.  


Edited by Eddgie, 23 April 2018 - 11:18 AM.

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#13 Eddgie

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Posted 23 April 2018 - 11:17 AM

And of course this is the Computar.  This is standard on the NVD Micro, but someone I think a while back told me that Night Vision Depot does not sell the lens individually.  

 

This lens is not perfect.  It has some off axis aberration, but it has nice build quality, is small, compact, and fairly fast.   I think the Fuji is fully equal in build quality and is not quite as compact as the Computar, but except for being very slightly slower seems to perform similar to the Computar in image quality.

 

Computar 25mm f 1.3.jpg

 

 



#14 Jim4321

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Posted 23 April 2018 - 11:35 AM

I've got the Computar f 1.3 25mm. It's fine, but so far for just low power scanning around I prefer an old film SLR lens I found among the used stuff at a camera shop.  It's a 58mm f 1.4 Minolta lens.  I've adapted a 2" longpass 610nm filter to it.

 

I really prefer its image scale to that of the 25mm.

 

I've also tried zooms, a Nikon 70-210mm f4-5.6, and a Computar 12.5-75mm f1.2.  Not bad, but I still like the Minolta best.

 

The Minolta & Nikon are C-adapted, of course.

 

One problem with most of these.... you can inadvertently stop the iris down while adjusting focus in the dark, resulting in a puzzling dimming of the view until you figure out what you've done.... D'uh!   BT,DT.

 

Jim H.



#15 outofsight

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Posted 23 April 2018 - 11:45 AM

I also use a Nikon lens with an F-C adapter. Mine is a Nikkor 135mm f/3.5 and I love it. In fact, it's become my most used piece of gear, with both the Mod-C and the PVS-7. These 135mm f/3.5 Nikons can be found on EBay all the time at very good prices.

My favorites too are 135mm F/2.8 Pentax, I think they're Sears, but am sure Sears had them made by someone else. After the 135mm I move to a Comet Catcher or something bigger. My Computar does OK, I pretty much hate the 3x standard magnifier and should get rid of it sometime.

 

I leave 685nm filters on the 135s, I think they might be 685s, or maybe Lumicon H-alpha Night Sky, whatever they are. The 135s have been my favorites since I got them, but I also like some simple 50mm for just a little bit of mag and a lot of light.

 

Also have some 200mm stuff that I don't use because for some reason the 135 just works for me.


Edited by outofsight, 23 April 2018 - 11:50 AM.


#16 Eddgie

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Posted 23 April 2018 - 12:48 PM

I have the 50mm version of the Computar f/1.3.  I totally scored getting it on Ebay for $50.   It is actually faster than the 3x afocal and has no vignetting (though if the good 3x is screwed on directly on to the front of the ENVIS/PVS-7/PVS14 id does not vignette either.  I do this under darker skies when I can run unfiltered).

 

There are some excellent old manual focus Nikon, Canon, Pentax and other lenses on Ebay too, so achieving almost any magnification is pretty easy to do.   

 

I wish someone made the CCD finders at f/3.9 using ED glass.   These work well at prime focus except for the fact that you have to long-pass filter heavily to keep stars sharp.

 

 

A slew of options though, but there is nothing like the ENVIS for 1x.  Of course someone that did not think they wanted the flexibility of C mount could always go with a PVS-14.   The SLR lens thing though is a major reason I like C mount. 



#17 outofsight

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Posted 23 April 2018 - 03:06 PM

I like C mount, period, and wouldn't buy anything, astronomically speaking, that wasn't C mount - even just for telescopes. The SLR lens aspects are simply icing on the cake. To be able to add 2x, 3x, or 5x or slightly more, with a good field of view and plenty of light, usually very cheaply, because of the way NV works is just stupendous. 

 

Think of it this way. Kevdog, getting lucky I should say, was able to buy a very nice Gen 3 TSE Prowler monocular for around $800. For $50 more, that's what I've paid for a Pentax based 135mm F2.8 and the Pentax to C mount adapter, you're right there at about 5x. Now it does depend on your viewing habits and what you want to ultimately do, but there's no other telescope system that you can pick up and walk out the front door with, in most of America or any city on the earth, and see all sorts of stuff that you can't see even with a much larger scope. So for $850 there is immediate access to the astronomical heavens. Actually, you should throw in some filters and that would immediately put it over a grand. That may be the best case scenario.

 

Now it also depends, some people never spend that much on a scope setup, but many of us spend thousands. If a person's going to spend $1500 or $2K or more on viewing the night sky, this is something to consider.

 

Some people buy eyepieces for their scopes, I buy scopes for eyepieces. Or I leave my 5x C mount setup in a drawer, when I want to use it I open the drawer with one hand, pickup my 5x DEEP SKY viewer with one hand, walk over to the front door and open it with one hand, while I'm holding my Deep Sky viewer in the other hand, go outside and can see more than 90% of the telescopes on the earth. 

 

Alright, I might be exaggerating some, I'm not really sure, but C mount night vision systems should be considered by more telescope users. Though I would never urge anyone to buy NV equipment at the expense of "regular" astronomy. What I mean is buy both. If you're considering a regular telescope, get one. If you're considering any of this stuff, investigate it.


Edited by outofsight, 23 April 2018 - 03:29 PM.

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#18 outofsight

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Posted 23 April 2018 - 03:25 PM

I should apologize to the Topic Starter too, I've written some stuff here without regard to the actual questions so I should at least throw a couple of cents in on that.

 

"I’ve also been looking at c-mount to Nikon adapters to use some of my camera lenses. Curious about how well they have worked for others."?

 

NikhilJoshi, since you already have them I'd go with a C mount adapter for your Nikon lenses before anything else. I'm sure you can tell by now how effective these lenses can be for NV. Usually, the faster the better, and one very nice thing about using older SLR lenses is how easy and cheaply they can be found, in case you don't already have enough from your Nikon system. 

 

"I also have a 2” 7nm H-alpha filter I was planning to use with purchased or 3d printed adapters if that factors into lens choice."?

 

You will absolutely want to use the 7nm H-alpha filter. You can ultimately get a 2" C mount adapter if you need one for a scope setup, and for Nikon camera lenses you should be able to fake it with step down rings? or the 3d printed adapters that you brought up. Normally you'd want to use a filter as wide as your objective lens, but in my experience it won't matter if it's fairly close (or maybe even not close). You may have to experiment some.

 

Your Hawaii question has been answered, have fun with that thing.



#19 NikhilJoshi

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Posted 23 April 2018 - 04:27 PM

Thanks to everyone for your feedback and commentary. I can't wait to receive the unit!  I think I will purchase a Nikon-to-c adapter and use my 50mm f/1.8 to start as my hand-held kit, with the fs-60c as the primary G&G scope for the NV unit. I'm also anxious to try it at prime focus with the TEC-140. 

 

How do the units hold up at prime focus and larger f-ratios?  I'm thinking specifically about my 180 Mewlon and Skywatcher 103mm Mak, both at  f/12 (and 2180mm and 1200mm focal lengths respectively).

 

This will give me something to do while the TEC-140 is imaging!

 

-nik



#20 chemisted

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Posted 23 April 2018 - 07:00 PM

I need to add a word about your 50 mm f/1.8.  I have the same lens and it would not fit into my Nikon to C adapter into which I had glued the old filter ring.  So, just go ahead and use your 2" filter in front of the lens and don't alter the adapter.

 

You will also have great fun at prime focus with both the scopes you mentioned.  I have taken my 140 mm refractor up to f/20 with no problems at all.  Enjoy!



#21 Eddgie

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Posted 23 April 2018 - 09:25 PM

Thanks to everyone for your feedback and commentary. I can't wait to receive the unit!  I think I will purchase a Nikon-to-c adapter and use my 50mm f/1.8 to start as my hand-held kit, with the fs-60c as the primary G&G scope for the NV unit. I'm also anxious to try it at prime focus with the TEC-140. 

 

How do the units hold up at prime focus and larger f-ratios?  I'm thinking specifically about my 180 Mewlon and Skywatcher 103mm Mak, both at  f/12 (and 2180mm and 1200mm focal lengths respectively).

 

This will give me something to do while the TEC-140 is imaging!

 

-nik

The tradeoff of slower focal ratio is higher noise.  Stellar targets bear slow focal ratios far better than dim nebula.  Globulars can survive pretty slow focal ratios.

 

While you can use slower focal ratios on galaxies, faster will often show more structure even though the target is smaller.

 

Nebula will suffer in proportion to both focal ratio and the bandwidth of the filter.  Even fast scopes will start to show the effects of noise when using very narrow pass filters (3nm, 5nm).  12nm will reduce the noise, but of course you loose some contrast.    

 

I recommend that you set the scope up with a filter wheel, so that you can try going between 12nm and a narrower pass (7nm, 6nm, and shorter). 

 

People report being able to use NV even on MCTs, so I won't say it cannot be done, but I will say that a faster scope will often show more structure even though the image scale is smaller. 

 

The great news is that you will be able to try if for yourself because it does not matter what we say, you will have to see for yourself at some point, yes?



#22 moshen

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Posted 23 April 2018 - 10:19 PM

I recommend that you set the scope up with a filter wheel, so that you can try going between 12nm and a narrower pass (7nm, 6nm, and shorter). 

I second the filter wheel idea. I have a 610nm, 645nm, 6nm Ha and a 2x barlow (in 1.25" filter cell - Harry Siebert can make one) in mine. It was the best thing I did for using a scope with my NVD.

 

Not having to fumble with filters and barlow in the dark and switching quickly between filters to find the best one for a particular object is a massive quality of life improvement.

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#23 Jeff Morgan

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Posted 23 April 2018 - 10:24 PM

How do the units hold up at prime focus and larger f-ratios?  I'm thinking specifically about my 180 Mewlon and Skywatcher 103mm Mak, both at  f/12 (and 2180mm and 1200mm focal lengths respectively).

 

Go for it!

 

H-alpha regions call for speed. But even then, the comparison is not f/10 vs. f/3. It's your conventional eyepiece in the Mewlon vs. the NV eyepiece in the Mewlon.

 

Stellar targets (star clusters) and high surface brightness targets (many planetaries and some galaxies) can do quite well at longer focal ratios  - provided there is a compelling reason for more scale. For example, and Elliptical galaxies offers little detail with larger scales. Stay fast on those. Edge-on spirals? Game-on!

 

https://www.cloudyni...-flong/?hl=+etx



#24 pwang99

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Posted 23 April 2018 - 11:14 PM

I barlowed up my C11 (f/10) under really dark skies for views of the Crescent and the Veil that I will never forget... :-)

 

(See https://www.cloudyni...-report-part-2/, under "Night Vision Changes Everything")



#25 slavicek

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Posted 24 April 2018 - 07:42 PM

Ok, I looked at my Ebay history and this is what I got.

 

I had purchased a lens called the NAV3 C mount from Nitesite on Ebay.    This is a C mount lens that looks kind of like the ENVIS, but is probably about f/1.3 or f/1.4.  The one I bought though had some slop in the focuser.   If you reversed focus, it you had to turn about 3/16th of an inch for it to start driving in the opposite direction.  It was not terrible, but I asked the seller to excange it, and he offered to substitute it with the Fuji and I thought the Fuji performed about the same, but with better mechanical finish.    The Fuji is very similar to the Computer differing only in being f/1.4 vs f/1.3 for the Computar.  Otherwise, it is mechanically very nice.

Here is a picture of the NAV 3 C mount:

 

attachicon.gif NAV 3 C.jpg

 

Agian, this is the lens that the seller subed for the NAV 3.  This is a very nice lens.  Made in Japan and I think very similar to the Computar:

 

attachicon.gif Fuji 25mm f 1.4.jpg

 

There is a catch though.   I spoke to the seller and he now has a minimum order of $500.   He is checking stock to see if he has either of these lenses or any ENVIS lenses gathering dust and he is going to contact me and let me know the inventory.

 

If he has any and there is sufficient interest, perhaps everyone that is interested can get together and come up with enough for the minimum order and work out re-distribution. 

 

Hope this helps.   Will post as soon as I hear back from Nightline.  

I will need Envis lens for my MOD3. If this will do the job of Envis (= afocal use with TV adapter) then I'd take 2 of these.

How much is each?

 

Vlad


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