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Potentially interested in a NV set up for visual only

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#1 Antares89

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Posted 26 March 2017 - 01:54 PM

A little background. I purchased a 10 inch Zhumell dobsonian last May and have fallen in love with the hobby. I could see myself enjoying this for a long time. I have access to fairly dark skies, 21.6 via SQM-L on a good night.

A couple of weekends ago, I was observing M51 for the first time. I could barely make out some spiral structure with averted vision and I could definitely see a 'gap' between the dust lanes/ spiral arms. I felt like I was just on the edge of being able to see a pretty good bit of detail if only I had more aperture, darker skies, or both.

I've been watching jdb_astro's videos on YouTube and have been admiring his NV setup. This got me wondering if a NV setup is what I'm looking for. I believe I read in another thread here on CN where a proper NV setup can have the effect of doubling the aperture of your scope.

Would a NV setup make the galaxies like M51 and some of the dimmer nebula come alive with detail? I'm not looking for Hubble like quality but it would be nice to be able to see spiral structure with direct vision. Would NV provide this?

Also, there is the question of which kind of tube to buy - green or white phosphor. Based on the videos I've seen, white phosphor looks more visually appealing. What are the pros and cons of each?

I have not yet been able to find a white phosphor monocular. I saw a white phosphor binocular setup but it was about $8000-$10000.

It seems that the PVS7 is very popular for amateur astronomy but uses a green image intensifier instead of white.

Another question I have is, is it even worth it to invest in NV for use with such an entry level scope? One good thing is the NV gear could be used as its own grab and go scope with the right accessories.

Any feedback and suggestions are welcome.



#2 Starman81

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Posted 26 March 2017 - 02:32 PM

Wow, those are some DARK skies! It would take me a LOOOOONG time to get bored with what I could see in skies like those with 10" of aperture, maybe like a decade!

 

Anyways, you are going to get a lot of great information from NV users, I think, but since I beat them to the punch, I can answer a few of your questions... 10" of aperture at a fast f/4.7 is anything but 'entry-level' for NV observing, I would argue, and for those objects that will fit in the FOV of any NV device, it should be pretty spectacular. But your views at 1x and 3x (with a proper 3x lens), I would be most eager for those type of views in your skies.

 

From latest reports though, edge-on galaxies are more enhanced with NV over face-on, but with M51 being so relatively bright already, I'm sure it will be enhanced as well. 

 

With such dark skies, you are not going to have to filter as aggressively as someone in light polluted skies so that is another big plus.

 

I don't think there are any cons when it comes to white phosphor vs green other than price. 



#3 The Ardent

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Posted 26 March 2017 - 03:07 PM

Edge on gx will be better most of the time, because theyre better visually too.

M51 is very nice with NV, M101 not so much. Same visually.

NV allows direct seeing of many GX's that are averted vision. Excellent for dust lanes (891, 4565, M64)

How the OP sees M51 in a 10" is normal, actually better than average. Trick is to observe it every time over the next few months. After about 10-15 times there will be lots more detail visible, simply from training the eye.

There is an aesthetic to visual that NV can't duplicate. There are views with NV that visual can never achieve. I belive in making the most of both worlds.

I find that after using the PVS7 for a while I don't notice the green color or noisy scintillation after a while. These are the two effects that new viewers always comment on. I "remember" my NV views as gray.

#4 bobhen

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Posted 26 March 2017 - 03:36 PM

You have a couple of choices: Astro Video or Night Vision.

 

I’ve been doing astro video since around 2001 and Night Vision for the last 13 months.

 

The Astro Video Route: 8” SCT (and driven GEM or driven alt/az mount) and an inexpensive astro video camera system like the Revolution Imager II. That type of set up will show you tremendous photo-like detail (easy and very detailed arms in M51) on a monitor in 30 to 60 seconds and photo-like detail in many other deep sky objects.

The complete Revolution imager system with small monitor and camera etc. is around $300. Astro video is easy but it feels (when you are doing it) a little more like long exposure CCD imaging than pure visual. But the images on the monitor WILL impress you.

 

The Night Vision Route: Night Vision Image Intensifier and a Ha filter (for nebula) and a Longpass filter (for non nebula) deep sky objects. Night vision feels (when you are doing it) just like visual observing. The intensifiers are no more complicated than using an eyepiece. You can use any mount (even non-driven mounts) and most telescopes work just fine.

 

The cost of NV is around 5 to more than 10 times what the inexpensive video cameras run. But NV is reasonable when compared to 4 or 5 TV Ethos eyepieces or the higher-end video cameras.

 

With your telescope, a NV image intensifier will EASILY show the Horsehead Nebula from the suburbs, many other invisible or hard to see nebula will be visible with more details and most will become easy targets. NV EASILY resolves faint open clusters and globulars and shows more detail in planetary nebula. All galaxies will be easier to see/locate but some will show more detail than others. The detail will be less than that with a video camera BUT the experience will be in real-time and more like visual observing. And on some objects NV gets very close to delivering actual photo-like detail – just dimmer.

 

The optical quality of the telescope is not all that important. Better is better of course but for NV top quality is not a priority. With NV, it would probably be better to have 2 average quality telescopes of different focal lengths than one great telescope – say your 10” and an inexpensive 4” F5 or F6 refractor or 6” F4 reflector and a small lens or 50mm fast refractor for very wide fields.

 

Spend your money on the best quality tube your budget will allow. Better to have a top quality green tube than an average quality white tube. The green tint really becomes a non-issue as your brain focuses on the detail.

 

Spend time doing research on Night Vision and Astro Video. Both have advantages and both will show you details in deep sky objects that are just impossible to see unaided.

 

If you do buy a new, night vision image intensifier from a dealer, don’t be afraid to ask for a discount off of the retail price – you WILL get it.

 

I use a NVD Micro monocular and love it. I live in the Philadelphia suburbs and with a 120mm refractor the Horsehead Nebula is now an EASY target!

 

HERE is a Night Vision website that will help answer more of your questions.

 

Bob



#5 Rickster

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Posted 26 March 2017 - 09:12 PM

First, I want to say that I agree with everything that Bob and Ray said, and they covered the subject well.  But since I have essentially the same scope that you have, and comparable skies, there are a few points I can emphasize. 

 

I think I have a fair idea of what you are experiencing.  The stars under dark skies are bright electric white pinpoints and the milkyway looks like it does in pictures.  But when you look in your 10" lightbucket, objects like M51 and other diffuse deep sky objects are faint gray smudges.  Not what you expected, right?  This was (to me anyway) disappointing.  The problem is that these objects have low surface brightness.  I wont go into the theory of it here, but the bottom line is that there is a limit to how bright these objects can be made to appear in a visual telescope, and you are near or at that limit with a 10" dob.  As you have surmised, NV is the solution. 

 

NV was my first astronomy related purchase that didn't disappoint me (despite its cost).  It exceeded my expectations.  It gave the views that I had imagined.  Your 10" dob with NV under dark skies would make you very happy.  I remember the first time I showed my wife M42 using my 10" dob and a PVS-7.  She exclaimed, in sort of a childlike far away voice, "what is that???"  (M42 seen through that combo is big and BRIGHT.)  I didn't want to disturb her, but after 20 minutes (literally), my toes were getting cold.  She had to go inside wanting more.  In contrast, she would previously only spend a few seconds looking at objects through standard eyepieces, and that was only to humor me.

 

Monocular vs biocular.  I much prefer biocular (PVS-7).  This may be because I have floaters in my eyes, or it may be because using both eyes gives a more immersive experience, or both.  Some guys have trouble merging images in bioculars/binoculars, and therefore prefer monocular. 

 

Green vs WP.  Like the others have said, you probably won't even notice the green after a few seconds.  And very dim objects will appear gray anyway (because they are too dim to be seen in color).  So I think the whole WP vs green decision is only about bragging rights and has no practical significance.

 

I ran a comparison (documented in a previous thread) and found that my 70mm Pronto with NV showed fainter stars  than my 10" dob (254mm) without NV.  So I think that NV more than triples the effective aperture.   And, as I noted above, this ratio is practically infinite for objects of low surface brightness, because NV will make low surface brightness objects visible that would be invisible even in a telescope 10 times larger (as hard as that may be to believe).

 

Having said all that, NV isn't perfect.  As The Ardent alluded, there are instances when standard eyepieces will show detail that NV wont.  For example, relatively bright objects like M31 and M42 sometimes show additional detail without NV.  I think this is because eyes have better dynamic range than intensifier tubes.  But for faint objects, NV is much better.

 

And, if you really want to see detail, EAA using a camera is even better.  The photon flux from some of these objects is so low that the only way to see additional detail is to accumulate the sparse photons over time before amplification.  Only a camera with a tracking mount can do that.    But that takes time (if only seconds or minutes).  It doesn't have the same feel as seeing in real time.  Seeing through NV is like having superman eyes. 

 

For me, the best of both worlds is to initially study the object using NV, then capture an image (showing even more detail) using a camera.



#6 Antares89

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Posted 27 March 2017 - 11:34 AM

Tons of great info here. Thanks a lot. I should note, if it matters, that my dob will soon have tracking capabilities as I'm having a custom EQ platform built for it.

The PVS7 does sound appealing to me in the sense that I've always felt my viewing experience would be improved if I could use both eyes. Is it possible to put a WP tube in a PVS7 'housing'?

Any ballpark ideas of what a good PVS7 set up might cost?


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Edited by Antares89, 27 March 2017 - 11:51 AM.


#7 Doug Culbertson

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Posted 27 March 2017 - 12:21 PM

With the PVS-7 you are pretty much locked in with the tube that comes with it unless you can find another PVS-7 tube with better specs, so if that is what you want, choose wisely!  AFAIK, there was never a WP tube for the PVS-7, and the military is no longer using this device, so no new tubes are being produced for it.

 

Having said that, I love my PVS-7, but I also enjoy a binoviewer. IMO, observing with two eyes is better than whatever additional benefits may be found using a monocular, but that's just me. 

 

As to good ones, I looked for a long time and found mine with an outstanding Gen 3 tube with no visible black spots. I picked it up on Ebay for $2k from a well rated seller with a money back guarantee. It so happened that he also used it for astronomy, and assured me that I would be happy with it, which I am. That price, of course, did not include the adapter for it to accept c-mount accessories.  All told, the PVS-7 with a new c-mount noseoiece from Nightline, a c-mount to 1.25" adapter, c-mount to 2" adapter and a couple of filters has set me back a bit over $2500, which is way less than a WP monocular alone. That does not mean that I don't want a WP monocular one day though. wink.gif

 

I have heard of PVS-7's with excellent tubes being found for less than what I paid, and I have found some for less. You might check out AR15.com as a lot of hunters are going with thermal units and selling off NV. 



#8 Jeff Morgan

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Posted 27 March 2017 - 02:42 PM

I've been watching jdb_astro's videos on YouTube and have been admiring his NV setup. This got me wondering if a NV setup is what I'm looking for. I believe I read in another thread here on CN where a proper NV setup can have the effect of doubling the aperture of your scope.

 

Firstly and most importantly, NV is the biggest leap in performance since Galileo. Much more significant than the "Dobsonian Revolution". Aperture can be thought of as "boosting the signal" in a crude way. This approach comes at tremendous increases in cost and weight.

 

NV boosts the signal the signal without the weight. Yes, it is expensive but less so than doubling the size of your scope.

 

Additionally, mirror coatings and eyepiece coatings only serve to minimize light loss, and they are already as good as they can get (materially if not mathematically). Any further gains in conventional approaches will be extremely marginal and cost ineffective. The only way left to significantly boost telescope performance is NV.

 

Another overlooked item is that NV gives you a portion of the spectrum where your retina is virtually blind.

 

Now, all of that being said, NV performance is uneven. You mentioned "doubling aperture". It doesn't quite work like that. It depends upon the object type and spectrum.

 

- Things that are strong in blue (reflection nebula) are generally AWOL in NV. The good news is that there are very few of these objects in the sky. Six maybe?

 

- Things that are strong in red get a strong response. Most objects in the sky have a healthy red component. Nebula are especially strong in NV. You will see things that are utterly beyond the reach of conventional. And you will see it with direct vision. How do you quantify that?

 

- Interestingly, many Dark Nebula are strong in NV. They emit nothing, but the stars around them are brought up to a degree where they contrast the dark nebula nicely.

 

I also skipped ahead and saw your post on the equatorial platform. If you are thinking of NV, be advised that NV is generally a lower powered form of viewing. Tracking may be handy for other observing, but it won't add much for the NV experience.



#9 Jeff Morgan

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Posted 27 March 2017 - 02:49 PM

The optical quality of the telescope is not all that important. Better is better of course but for NV top quality is not a priority. With NV, it would probably be better to have 2 average quality telescopes of different focal lengths than one great telescope – say your 10” and an inexpensive 4” F5 or F6 refractor or 6” F4 reflector and a small lens or 50mm fast refractor for very wide fields.

 

Yes, NV is low-powered viewing. Not as demanding as planetary and double star observing where you are working at a high mag per inch of aperture.

 

What you want to pay for is speed.

 

If you will indulge me in a small sidetrack which hopefully is still useful in this thread:

 

When you move into faster Newtonians, what is the necessity of coma correction?

 

A Paracorr exacts a speed penalty of 15% (or about 30%) in brightness. So, a simple question: in a fast Newtonian does an NV eyepiece show coma like a conventional eyepiece?



#10 The Ardent

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Posted 27 March 2017 - 03:20 PM

I don't notice coma with the NV. It's there, but not objectionable.
With standard 15mm eyepieces, coma is horrible.

A buddy just got an Orion 12" f/4.7. He didn't notice any coma, but I did. But it wasn't objectionable.

The NV bloats the star images so that coma and miscollimation aren't seen as well as visual. Add low magnification....effective in masking optical deflects in a newt.

NV can be effective for double stars, for seeing faint components not too close to the main star, that are too faint normally.

NV is also good for faint clusters like NGC 5053.

Iirc, when I tried the PVs7 with the Paracorr, since the nosepiece doesn't move as far inside as an eyepiece, I was unable to focus. Never tried it again.

#11 Jeff Morgan

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Posted 27 March 2017 - 05:52 PM

I don't notice coma with the NV. It's there, but not objectionable.
With standard 15mm eyepieces, coma is horrible.

 

...

NV is also good for faint clusters like NGC 5053.

Thanks for that. One of the things I am wrestling with is putting money into a large and faster mirror - only to get the coma corrector speed penalty. It seems counter-productive and there has to be a better mouse trap ...

 

Baader makes a zero-power CC, but reports indicate it is more of a "coma reducer" than "coma corrector". OTOH, maybe it would be good enough ...

 

Or I could go all-in for a PowerNewt or Takahashi Epsilon. Blazing f/2.8 speed. Twice as bright as f/4. But I am curious how well a "consumer grade" system will hold together at that speed level (focuser and tube flexure, collimation). Anxiously waiting Eddgie's report on the PowerNewt. 

 

Who knows? It may turn out that the f/4 to f/5 realm is the best balance of performance and economics. It would be nice since those mirrors are as common as fleas.

 

With respect to faint clusters - just for fun I was using my Mod 3 in a Meade ETX 90. If the Tak Epsilon is blazing at f/2.8, the ETX is glacial at f/13.8. But it did surprisingly well on NGC2354 and NGC2362 in Canis Major. Not faint in an absolute sense, but faint for the ETX from light polluted suburban skies. Add to that 2354 (listed at mag 6.5) is pretty sparse. The view in the Mod 3 was better than the 22 Panoptic in both cases! Kind of a shocker for me.

 

NV really brings out the fainter members. In fact, it brings out non-cluster members too, so in some cases (not well-detached clusters) it could be too much of a good thing. Gain control really pays dividends here. Overall I think NV has a promising future for open cluster observing.



#12 pwang99

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Posted 27 March 2017 - 06:14 PM

Another thing is that I saw the moons of Uranus and Neptune with NV.  It was pretty borderline given the atmospheric conditions, but it was neat to be able to do that.  I wonder about looking at other faint solar system objects (including comets) with NV... I don't recall very many observing reports about that.



#13 The Ardent

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Posted 27 March 2017 - 06:43 PM

Jeff
I believe that with NV in a dob, the f/# isn't as important as the aperture. So if you're using the f/7 you're not missing out on much vs having an f/4.
I'm sure there may be some improvement, but in trying NV in other dobs (usually f/5) aperture was the difference maker.
I'm sure that there is a "too slow" and a "too fast" for NV, but I'm not sure what that is.

Paul
I'd like to try comets and asteroids, just haven't yet. Thanks for the idea.

#14 bandhunter

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Posted 27 March 2017 - 07:27 PM

I don't know as much about the technical aspects of NV as the other posters, lots of great info guys, but I know it gives me the views that keep on amazing me.  I have what I believe to be an exceptional example of a WO 66SD, planetary views amaze with good seeing, Jupiter moon transits obvious at 77x etc.  Also really good darksky performance on faint fuzzies as well. BUT... not in my home red/white light pollution skies.  NV gives me dark site capability with my baby frac in suburban skies, priceless.  Small faint clusters that I would never see in eyepieces jump out at you when your scanning, and you get that "discovery" excitement.  Views of M81/82 in the 66 and Pvs7 mimic standard wide field eyepiece views in my 10 inch under yellow skies. Jaw drop.

 

And then the 1x viewing...  With my 13nm ha filter(thanks The Ardent!) The California, north American, Rosette, and even Barnard's Loop are just right there.  Am I using my imagination? Nope there they are even in the light pollution.

 

I like galaxies, and a 10 inch with the PVS7 do not disappoint especially on the edge on galaxies.  The Sombrero is a show stopper, 30 minute view easy the first time. Picturesque.  And look out Galaxy chains here I come.

 

I got my PVS7s from a guy that kind of collected and semi sold them on a shooting forum.  His normal ones could be had for 1400-1500$.  I told him I need a pair with a high end tube for astronomy, he said I have just the pair, he sent snapshots of the tube view and I showed the very minor blemishes, which I can't see when observing, on here and the guys said they weren't an issue.  So I got them for a little under $2000.  Seem to be somewhere between Omni 7 and 8 based on charts I've seen.  Never used another pair for this so can't compare but I think they are good ones. I wouldn't sell them for less than 2k.  Deals are out there but it takes time and research.  Used is always a gamble, what if the tube stops?  Had a scare the other day when I went to turn them on and had just put in fresh batteries nothing happened.  Turned out to be a bad battery.

 

If you take the plunge you will not regret it. As others say, come to the green side.



#15 The Ardent

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Posted 27 March 2017 - 07:36 PM

I saw the double quasar next to NGC 3079 for the first time last week. It was just a tiny spot , just barely visible at 120x. A friend had a photo of the starfield and galaxy, was simple to match the star patterns. I was told that it was a threshold object with a 24" at WSP, and probably with very high magnification.

The galaxy was nice too.

Here is a good look link
http://www.cloudynig...n-quasar-at6rc/

#16 Antares89

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Posted 28 March 2017 - 09:18 AM

Thanks again for all the info. I think the main question now is whether to go with green or white phosphor.

I will say that the pvs7 (green) is attractive due to being able to use both eyes to observe.

Also, I saw a side by side comparison of green and white phosphor on ar15.com and in some of the pics, the WP made the sky looked slightly washed out. It could have just been the camera settings. Has anyone experienced this?


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#17 Jeff Morgan

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Posted 28 March 2017 - 09:34 AM

Small faint clusters that I would never see in eyepieces jump out at you when your scanning, and you get that "discovery" excitement. 

Yes!

 

You'll stumble across things that are known to imagers, are relatively unknown (and unavailable) to visual observers and don't show up on star charts:

 

https://www.cloudyni...very/?p=7550775



#18 Jeff Morgan

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Posted 28 March 2017 - 09:38 AM

Jeff
I believe that with NV in a dob, the f/# isn't as important as the aperture. So if you're using the f/7 you're not missing out on much vs having an f/4.
I'm sure there may be some improvement, but in trying NV in other dobs (usually f/5) aperture was the difference maker.
I'm sure that there is a "too slow" and a "too fast" for NV, but I'm not sure what that is.

 

Thanks for that. Definitely my experience base with different host telescopes needs to grow a bit before plunking down $6K on an Epsilon. I'll cool my heels and credit card for a little while!

 

The basic problem with this hobby is the time to think about equipment vastly exceeds the time to use equipment, leading to grandiose plans.



#19 Jeff Morgan

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Posted 28 March 2017 - 09:46 AM

Thanks again for all the info. I think the main question now is whether to go with green or white phosphor.

I will say that the pvs7 (green) is attractive due to being able to use both eyes to observe.

Also, I saw a side by side comparison of green and white phosphor on ar15.com and in some of the pics, the WP made the sky looked slightly washed out. It could have just been the camera settings. Has anyone experienced this?


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Be advised that the white tubes actually have a slight blueish tint. After a minute or so you stop noticing it. Ironically, this is what the guys with green tubes say too!

 

My understanding is that you can have a PVS-7 in any color you want as long as it is green.



#20 Antares89

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Posted 28 March 2017 - 10:18 AM

So it appears the PVS-7 is the gold standard if one decides to go green.

What are the options if one decides to go the WP route?

I should note that whatever set up I go with will be used for hand held use as well as use with my scope.


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#21 Eddgie

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Posted 28 March 2017 - 01:37 PM

So it appears the PVS-7 is the gold standard if one decides to go green.

What are the options if one decides to go the WP route?

I should note that whatever set up I go with will be used for hand held use as well as use with my scope.


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Don't be confusing the PVS-7 as the gold standard of anything. 

 

The PVS-7 has a very complex set up optics (even the eyepieces use plastic lenses and there are mirrors in the light path).  The eye relief is also very short.    Even with an identical tube (if you could find one which is impossible for the higher performance tubes) the PVS-7 will not produce a view with the clarity and sharpness of a top end monocular and you can get far better tubes for the monoculars in both green and white than you can get in the PVS-7.

 

Also, while it has not been mentioned here, the PVS-7 does not have gain control. Gain control allows you to vary the gain to reduce the scintillation. 

 

The Mod 3 has all glass lenses and these focus directly on to the rear of the tube, so there is no relay device, beam splitter, and light redirection (plastic mirrors) to degrade the image.   Now I am not saying the image in a PVS-7 can't be quite good to use, but as compared to pretty much any monocular made, they will always fall short for how pinpoint stars can appear.   The Mod 3 also has gain control.

 

I own both a PVS-7 with a very high performance tube, and I own an AB Night Vision binocular with two L3 Filmless tubes.   As much as I love using two eyes and as much as I used to use the PVS-7 exclusively in the telescope, more and more, I find myself putting in one of the monoculars because the view is simply better in pretty much every way.   Now having been a dedicated binoviewer user in the past, I did not think I could ever go back to monocular observing, but when the difference in performance becomes so much superior, you might start to accept that one eye can be better than two. 

 

These days, if one can afford a Mod 3 with filmless tube, my advice would be to go there first.  Performance wise, it is impossible to get into the same performance class with a PVS-7 as you can get with a monocular and modern filmless tube. 

 

It is expensive, but it is worth it.

 

(if the view looked "washed out" it could have been many factors.  With gain control on a WP tube, you can fool someone into thinking they are looking though a regular eyepiece if you want to do that). 


Edited by Eddgie, 28 March 2017 - 01:38 PM.


#22 Jeff Morgan

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Posted 28 March 2017 - 08:54 PM

Don't be confusing the PVS-7 as the gold standard of anything. 

 

The PVS-7 has a very complex set up optics (even the eyepieces use plastic lenses and there are mirrors in the light path).  The eye relief is also very short.    Even with an identical tube (if you could find one which is impossible for the higher performance tubes) the PVS-7 will not produce a view with the clarity and sharpness of a top end monocular and you can get far better tubes for the monoculars in both green and white than you can get in the PVS-7.

lol.gif

 

I keep thinking if I had more time and money on my hands (both of which are very over-subscribed at this moment) I would love to try and graft one of the new L3 filmless tubes onto a Denkmeier Binotron ...

 

Could be the best of all worlds.

 

Or a waste of $6,000.



#23 Eddgie

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Posted 28 March 2017 - 09:33 PM

A waste of $6000.  

 

The collimator in a PVS-7 is a very complex transfer lens that essentially projects the rear window of the image tube to the field stop of the eyepieces. There is no way easy way to stick an image intensifier on to the front of a binoviewer and get the image to the field stop.  I suppose it could be done with a series of transfer lenses, but now you have simply replicated the complexity of the PVS-7 collimator. 

 

You could run two monoculars in a binoviewer as eyepieces, but now each intensifier would only get half of the light and just like when using eyepieces, the image would be dimmed.   Someone tried it (reported the result on Binoviewer forum) and said it did not work as well as a PVS-7.  

 

Whatever shortcoming the PVS-7 has, it does work exceptionally well for what it is, and if the absolute most important thing is to use two eyes, it works quite well.  It just does not work as well as the monocular when it comes to absolute quality of the view.

 

Now, if you wanted to hack something, converting a PVS-7 to use a filmless tube would be the way to go.  The image would be inverted, but for telescope use, this would not matter.  I don't think the optics of the PVS-7 hold it back as much as the tube technology does. 



#24 Jeff Morgan

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Posted 29 March 2017 - 12:36 AM

Now, if you wanted to hack something, converting a PVS-7 to use a filmless tube would be the way to go.  The image would be inverted, but for telescope use, this would not matter.  I don't think the optics of the PVS-7 hold it back as much as the tube technology does. 

 

Winds out the north 15 gusting 25 tonight. Plenty of time to think about such money pits.

 

I never did look at it that way though. A PVS-7 body would be less than a Binotron.

 

Either path starts with a rather expensive tube though.



#25 Jeff Morgan

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Posted 29 March 2017 - 12:38 AM

OTOH, I did just finish watching Risky Business.

 

All I have to do is meet a girl named Lana ... cool.gif




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