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PVS-7 Night Vision for Astronomy

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#1 Eddgie

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Posted 23 February 2016 - 09:58 AM

Anyone that has never looked though a later, higher performance Gen 3 night vision device cannot really appreciate how sharp and clear of an image these devices can provide.

Their low light performance make them able to show just about any field anywhere in the sky appear filled with stars, but more interestinly is the fact that their near infra-red sensitivity allows them to see emission nebula that would be difficult to see for most observers any other way.

 

This post will focus not one the observing, but more on the modes of operation.  I think it is important to do this because a lot of people think the tech is to expensive, but when you look at the different modes of operation, you start to realize that not only do you get new capabilities that you would never otherwise have had, you also get the ability to increase the performance of your existing equipment.

 

The base mode of operation for the PVS-7 is to use it at "Unity"   (night vision term for 1x).  The standard fast focusing objective is a very fast lens with about a 26mm focal length.   Because the eyepeice is also about 26mm in focal lenght, the power is 1x.        The apparent field of the eyepecie is 40 degrees, so this makes it easy to crunch the numbers to reveal that the true field is a pretty staggeringly big 40 degrees.   In a community that buys ever smaller refractors for ever wider fields, this kind of device reins supreme for getting the biggest, widest, brightest field possible.    Sweeping though the Milky Way at Unity, or observing Barnard's loop in its full glory, even from mag 5.5 skies (deep suburbs, so no two hour drive required for most observers) is something that has to be  seen to be appreciated.   

 

The advantage of not needing a mount or external power, and don't need cool down or dark adapted eyes to see staggeringly rich vistas is only icing on the cake.   
 

Here is the PVS-7 configured for unity with a 6 x 30 finder shown for scale.  PVS-7 is super light and very compact, being similar to a 7x x 42mm binocular in size and weight.

 

PVS-7.jpg

 

The next mode of operation is to use an inexpensive afocal clip on lens.   This large bulb at the rear of the device is a snap on connector with splines that lets the lens slide over the PVS-7 lens and snap in place.   The most common lens is the 3x lens.   This does not seem much different in power to be worth it, but think of it this way..  When you are working with very small things, an 8mm to 24mm zoom offers a considerable range of magnification right?  That range though is only a 3x range!    When you are working with huge things, that same 3x range actually makes a considerable difference.  Many small nebula are visible easily at 1x, but will resolve considerably better at 3x in exactly the same way that zooming in from 24mm to 8mm using a  telescope will enhance the view of a globular cluster.

 

Here is the PVS-7 configured with a 3x afocal lens.  The setup is so super-light weight and even viewing at zenith for long periods of time is quite practical, but putting on a headset and snapping the PVS-7 into its connector, and viewing while reclining in a lawn chair is a super comfortable way to scan the sky at zenith.

 

Binoviewer.jpg

 

 

The next mode of operation is to replace the military objective assembly with a C mount adatper.  C mount derives from the old 16mm movie camera format (Cinema, or Cine).   The objective assemble of the PVS-7 simply unscrews, and this adatper takes its place.   There is no lens in the C mount, but the beauty of the C mount is that it allows you to mount a wide variety of camera lenses.   CCTV and Cine lenses simply screw right on, but the real beauty is that you can buy adapters for most common 35mm SLR camera formats.   For example, if you have old Nikon lenses, a $25 adapter will let you turn them into astronomy lenses for your PVS-7.   The cazy thing is that you can often find very good SLR camera lenses on Ebay for less than the price of a decent plossl!!!   I paid $30 for shipping for the lens in the picture.  It is a 200mm f/3.5 Vivitar lens, and with it, (and an H-a filter mounted between the lens and the PVS-7) I can see the Horse Head nebula from my light polluted front yard.     A 200mm lens will give almost 5 degrees of true field but becuase the power is only a bit over 8x, hand holding is still possible as compared to a very large binocular which can be very expensive, probably has a smaller field, and will require a mount to hold.

 

5 degree green sky.jpg

 

SLR Zoom lenses also work great and this allows you go either keep in cheap or if you want the best performance, use more expensive, faster zooms which will be heavier, but will show nebula brighter and with better detail.  Here is a picture of a PVS-7 with multiple lenses and is included just to show how flexible this system can be. In the picture, you see a 35mm to 105mm f/2.8 zoom, an 80mm to 200mm f/2.8 zoom, an ENVIS lens (which is a C mount threaded lens very similar to the lens that comes on the PVS-7, but allows you go go back to 1x without having to re-install the standard lens) and on the right, you see the focus of the next mode of operation, which is a 1.25" nose-piece. You can also see a very small, inexpensive CCTV lens (about $25 on Ebay for a 25mm F/1.3 CCTV lens) making for a budget alternative to the ENVIS lens which is shown just in front of the C mount housing.

 

 

PVS-7 configuration resized.jpg   

 

Let's go there now.   The last mode of operation is to mount a 1.25" or 2" nose piece in the C mount opening.   Unlike a regular binoviewer, the PVS-7 will reach focus in just about any telescope made. Is all you have to do is thread on the noze piece and slip it into the focuser.   Also, unlike a traditional binoviewer, the light path is not dimmed by 50%.  In fact, both eyes see the same bright signal.

 

Using a high performance PVS-7 can be like doubling the aperture of an existing scope, and even from light polluted skies, an H-a filter produces nebula views that would be difficult to get from the same scope even under all but the darkest skies you could get to.    The first time I saw the Swan nebula in my 12" dob from my light polluted back yard (a target I had seen many times before) I was literally astonished but the detail present, but more than that, by the huge expanse of nebula around the swan that I had never been able to see before.   My girlfriend, who had see the Orion Nebula many times before, pretty much gasped when I called her out to see it in the PVS-7.   She said it was like looking though the Hubble telescope.

 

From my light polluted back yard with the PVS-7 in my 140mm Comet Catcher, I can see stars in M29 that I struggle to see in my 12" dob, and with it in my 12" dob, I see stars that I would have had to take my C14 to dark skies to be able to see.  Even M22 at 19x in a 140mm Aperture will be so big and bold that it will surprise just about anyone.

 

Prices of used PVS-7s make them far more affordable than people think but most people will are not aware of the full flexibility of this kind of system and when you factor in the new regimes of ultra-wide field observing ( I call it "Big Field" observing) and the enhancement performance to existing scopes (thinking about buying a bigger telescope but worried about the weight or the transport effort?) the cost starts to make far more sense.

 

And then there is the absolute joy of being able to walk out of your front or back door at night, and without any setup, on a decently clear night from a light polluted sky, look up, and see the North American or California Nebula.

 

If you are unfamaliar with this technology, I would refer you to the Electronically Assisted Astronomy forum (just below refractors) for more details about the equipment and to hear very compelling accounts of people that have recently purchased gear and have turned it to the sky and shared their first light experiences.

 

I picked the PVS-7 for this because prices are falling, but there are monoculars and true binoculars as well.  The PVS-7 is just out there in such huge numbers that it is the most affordable entry point.

 

Hope this thread is interesting to someone and if you have any questions, I would be happy to answer.


Edited by Eddgie, 23 February 2016 - 01:45 PM.


#2 Eddgie

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Posted 23 February 2016 - 10:03 AM

Here is the PVS-7 in the Comet Catcher.  Interstingly, I can actually cradle the Comet Catcher in my arms and observe without using a tripod and get a reasonably good view.  Form my light polluted front yard, I was able to easily see the notch in the Horsehead.

 

Comet Catcher on Minitower.jpg  

 

 

 

In the dob, the outline of the horses head is easy to fully resolve, and again, that is from my light polluted yard.   I can see stars in M29 using the 12" dob that previously required taking my C14 to dark skies to see.

The image intensification in faster scopes makes every field look like a rich field, and the nebula performance has to be seen to be belived.

 

PVS-7 binoviewer.jpg


Edited by Eddgie, 23 February 2016 - 01:49 PM.


#3 Doug Culbertson

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Posted 23 February 2016 - 10:32 AM

Great post! BTW, you mentioned placing a Ha filter between the SLR lens and the PVS-7. How is that accomplished? I know that you need a lens specific (Nikon, Pentax K, etc) to C-mount adapter, but where does the Ha filter fit into that train?



#4 Jeff Morgan

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Posted 23 February 2016 - 01:57 PM

A very informative and illuminating post!

 

We all have read reviews of the The Next Great Thing that "everyone" will be doing in a few years. That is an absurd idea given the breadth of interests within the hobby, and I'm glad you're not pushing that.

 

Yet with the high costs and physical limitations of large aperture and the relentless growth of light pollution, I see a huge potential for these devices will be commonplace in the astronomy community. I would love to have my 16" perform like a 32", and going to the dark sky site is a burdensome (and time inefficient) expedition.

 

Of course after 30 years of marketing efforts, the Nagleristas will rebel at the thought of 40 degree AFOV. But hey, different strokes.

 

A few questions come to mind on this:

 

1) Supposing one buys a used PVS-7 and finds the tube to be unsuitable for astronomy (low specs, blems, whatever), or just gets hooked and wants a higher spec tube. Is the intensifier section easily removed at home, or does one buy an entire new assembly?

 

2) The clip-on lenses you show appear quite fast, and telephoto lenses are also easily available in f/2.8 (and faster). How do the PVS-7 eyepieces handle the speed? Do you get a lot of edge astigmatism?

 

3) Inevitably, people will wonder about "hot rodding" one of these units by swapping the supplied eyepieces with something a little more common in the astro community. 24 Panoptics perhaps. Do you think this would be possible?

 

4) Looking at what is currently available on the market, it seems the monocular tube specs are higher (30 S/N ratio for the NVD Micro vs. 25 S/N for the PVS-7's). Is this just a snapshot of what vendors have at this instant, or do the monoculars have higher performance?

 

5) A silly question, but is there such a thing as averted vision in the NV world? Or, is it pretty much all laid bare?


Edited by Jeff Morgan, 23 February 2016 - 01:58 PM.


#5 Eddgie

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Posted 23 February 2016 - 01:59 PM

The easiest way to do it is to get an old 1.25" colored filter and remove the class.    Next, you use some epoxy to secure the base of the old filter cell on to the bottom of the inside of the SLR to C mount adatper.

 

Now you can simply screw the H-a filter into the top of the old filter cell in the same way you would stack filters.

 

Some cautions.  Some SLR lenses will have some sub-aperture elements that would protrude into the SLR to C mount adapter so you have to make sure that the two filter cells stacked together will allow clearance.

 

It can be fiddly getting the filter started or removing it if you have big fingers.  It is not necessary to screw the filter in tight.   

 

Last, if the lens is very fast, stacking the filters could result in some aperture loss or vignetting.   

 

Some people use large H-a filters that are mounted to the front of the SLR Lens using step down rings, but I have some very large SLR lenses and this is not practical for that.  

 

I mean suppose I were to put a step down ring on my 77mm 200mm f/2.8.  If I used a very expensive H-a 48mm H-a filter, I would turn lens into a 48mm f/4.1 lens.

 

I chose to go with this method because even my $20 Vivitar lens is f/3.5, and the 1.25" H-a filter was much cheaper than a 2" filter.



#6 Eddgie

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Posted 23 February 2016 - 02:09 PM

 

 

1) Supposing one buys a used PVS-7 and finds the tube to be unsuitable for astronomy (low specs, blems, whatever), or just gets hooked and wants a higher spec tube. Is the intensifier section easily removed at home, or does one buy an entire new assembly?

 

2) The clip-on lenses you show appear quite fast, and telephoto lenses are also easily available in f/2.8 (and faster). How do the PVS-7 eyepieces handle the speed? Do you get a lot of edge astigmatism?

 

3) Inevitably, people will wonder about "hot rodding" one of these units by swapping the supplied eyepieces with something a little more common in the astro community. 24 Panoptics perhaps. Do you think this would be possible?

 

4) Looking at what is currently available on the market, it seems the monocular tube specs are higher (30 S/N ratio for the NVD Micro vs. 25 S/N for the PVS-7's). Is this just a snapshot of what vendors have at this instant, or do the monoculars have higher performance?

 

5) A silly question, but is there such a thing as averted vision in the NV world? Or, is it pretty much all laid bare?

 

The tube is super-easy to remove.   When you unscrew the objective housing, the tube simply pulls out of the front.  There are no contacts or connectors that have to be manually made.    Super easy and only requires very simple precautions.

 

Cnoct has a video on Youtube.   He does if for a PVS-7 A, but the B and D it is even easier because there is no lock clip to pry down.

 

Question 2, and excellent question.    The eyepeices are looking at a phosphor screen.   The view is very sharp right to the edge. 

 

Remember, when you desing a system for one eyepeice, you can fix any aberation you like because you don't have to worry about how it will work with different eyepeices.   Also, even a Plossl, if limited to 40 degree apparent field, can provide sharp images even in fast systems, but here, you are not really looking at the light cone.  You are looking at a phosphor screen.

 

The field of of the PVS-7 is dead flat.   If you use it in a scope with field curvature or coma or other aberrations, then of course the phosphor dots will appear aberrated, but not because of the eyepeice at all.  I this case, you only see what the scope contributes.

 

Not possible to swap eyepecies in the PVS-7.    And frankly, not really desirable.    The 40 degree apparent field sounds claustrophobic, but in practice, this field will be so crazy full of stars that you simply don't notice

When you can fit all of the Constellation Orion in the same field of view, and see the Flame, Horeshead, Rosette, Anglefish (ever heard of that one???) and Orion Nebula in the same field of view, you are to busy trying to restart your breathing to notice that the apparent field is narrow.

Yes,  you can use averted vision.  I don't think the gain in limiting magnitude is a as good as with conventional eyepieces, but with night vision, stars that are very difficult to see with high power and averted vision will be easy in the device.


Edited by Eddgie, 23 February 2016 - 02:20 PM.


#7 Eddgie

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Posted 23 February 2016 - 02:20 PM

And an interesting note.  I had never heard of the Angelfish nebula before starting to use NV.   Heck, I had never heard of half of the Nebula I can see now.  I had never heard of the Heart and Soul Nebula either, and had tired for years to see North American nebula (which I can now see even from my heavily light polluted front yard and wow is it big!

 

I had always dreamed of seeing Barnard's look, and I have heard of people doing it form high elevations and very dark skies using nothing but a filter.

 

I have not seen it that way, but I cannot imagine it would have been as prominent and detailed as I could see it in my PVS-7 from Mansfield Dam.

 

Mansfield Dam is a 20 minute car drive from my central Austin home.   15 years ago, skies there were mag 6 on a decent night.    Now, it is hard to find Mag 5.5 at zenith, and closer to the Horizon it is more like Mag 4 to Mag 4.5.

 

The first time I saw Barnard's look, It floored me.    How amazing!  It was so large, and so clear!  

 

JDB_Astro has a Youtube video of Barnard's look that he took in real time from his observatory under pretty reasonable dark skies, and it is nothing short of magnificent.    

Cnoct (one of our most knowledgeable members and a great inspiration to me) has posted some incredible videos too.  Search Carpenocturnum Night Vision Astronomy on Youtube.

Remember, when you watch these videos, they are real time, and what they will tell you if you ask them that seeing the subjects though the eyepeice usually provides and even better view! 


Edited by Eddgie, 23 February 2016 - 04:38 PM.


#8 Doug Culbertson

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Posted 23 February 2016 - 02:37 PM

Thanks for the information re: the Ha filter with a camera lens.

 

As for the Angelfish, I had never heard of that one either, nor had I heard of the Seagull nebula in Monoceros, but they sure are easy targets in the PVS-7! Oh, while I had seen faint nebulosity in the California nebula in a largish telescope, looking at it just hanging in the sky with the PVS-7 it actually looks like California. Amazing stuff, simply amazing.



#9 Jeff Morgan

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Posted 23 February 2016 - 09:04 PM

Cnoct has a video on Youtube.   He does if for a PVS-7 A, but the B and D it is even easier because there is no lock clip to pry down.

 

Question 2, and excellent question.    The eyepeices are looking at a phosphor screen.   The view is very sharp right to the edge. 

 

Remember, when you desing a system for one eyepeice, you can fix any aberation you like because you don't have to worry about how it will work with different eyepeices.   Also, even a Plossl, if limited to 40 degree apparent field, can provide sharp images even in fast systems, but here, you are not really looking at the light cone.  You are looking at a phosphor screen.

 

The field of of the PVS-7 is dead flat.   If you use it in a scope with field curvature or coma or other aberrations, then of course the phosphor dots will appear aberrated, but not because of the eyepeice at all.  I this case, you only see what the scope contributes.

 

Not possible to swap eyepecies in the PVS-7.    And frankly, not really desirable.    The 40 degree apparent field sounds claustrophobic, but in practice, this field will be so crazy full of stars that you simply don't notice

 

I watched the video, it looks trivially easy. Pretty much plug-n-play.

 

I'm guessing then that the "tighter" intensifier specs (S/N, photcathode response) on the NVD Micro are more a function of it being a newer offering, or current market demand? Perhaps NV Depot, NAIT, or Wilcox could put together a PVS-7 with the Pinnacle ULT tube found in the Micro?

 

With respect to the Newtonian, do you still use a Paracorr?



#10 The Ardent

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Posted 23 February 2016 - 09:18 PM

I can use a Paracorr, but the coma isn't objectionable unless a focal reducer is involved. YMMV

An ideal setup to me is an astronomical binoviewer with night vision tube as the nosepiece. Kinda what the PVS-7 is, but able to use 1.25" eps. I think the BIPH was this, but not sure:

As far as averted vision, yes on the really faint (Maffei II, some Sharpless)

Many of the 1 to 5 star ratings in NSOG apply to night vision also.

#11 JumboFlex

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Posted 23 February 2016 - 10:05 PM

It is a compelling tech for astronomy and after reading previous posts and Eddgie's excellent topic starter above it makes me really curious about it.

 

If I were to to make a comment that may be a touch negative, but recognizing the distinct advantages of this tech for astronomical observing for us amateurs, it is simply the notion that the image is, to my eyes at least, unnatural. I don't mean this to denigrate the tech or those who champion it in any way - it does demonstrate remarkable detail, especially if the youtube vids I have seen were taken from run of the mill backyards, but I think I would miss the colours and the images, at least those I have seen posted, appear a bit processed: you are looking at a screen (aside from the phosphor green even) with a bit of interference/grain whereas with decent glass you get a more "natural" appearance. 

 

If I were to add this to my observing armamentarium I think it would be a complementary piece more specialized for nebula or just random sky surfing. Given what Eddgie states in his post this  seems to be where this tech has most benefit. It would also be nice just to simply turn it on and go, excellent GnG setup.

 

Wonderful stuff though even with my personal caveats.

 

Thanks for the informative and enthusiastic post, Im gonna go regoogle the gear. 



#12 Jeff Morgan

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Posted 24 February 2016 - 02:38 AM

If I were to to make a comment that may be a touch negative, but recognizing the distinct advantages of this tech for astronomical observing for us amateurs, it is simply the notion that the image is, to my eyes at least, unnatural. 

 

Realizing that you are looking at a phosphor screen is different for sure. I recently tried the Mallincam and didn't like it. But, Mallincam was more like using a computer, and was not real-time. I am hopeful NV will be more like using a regular optic (despite the phosphor screen).

 

OTOH, NV gets you the infrared part of the spectrum you can't normally see. Highly unnatural, but sounds like a bonus to me.


Edited by Jeff Morgan, 24 February 2016 - 02:43 AM.


#13 Eddgie

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Posted 24 February 2016 - 09:27 AM

Jeff Morgan, on 23 Feb 2016 - 8:04 PM, said:

I'm guessing then that the "tighter" intensifier specs (S/N, photcathode response) on the NVD Micro are more a function of it being a newer offering, or current market demand? Perhaps NV Depot, NAIT, or Wilcox could put together a PVS-7 with the Pinnacle ULT tube found in the Micro?

With respect to the Newtonian, do you still use a Paracorr?

 

The PVS-7 could have tubes every bit as good as the NVD Micro in terms of performance specs. 

For example, my NVD Micro has a signal to noise ratio of 30 and a photocathode response of 2500 and 64 lines of resulution.

 

My best PVS-7 (I have two) has a signal to noise ration of 31.8, and a photocathode response of 2525 with the same EBI and Halo numbers

.

Now, here is the problem.   In a general sense, tube specs peaked at the Omni VII government contract requirement.   The following contract lowered the performance requirements.   This means that it allowed manufactures to decrease performance, and the speculation I have seen suggests that this was because it was to hard to produce the Omini VII tubes, which of course made the price higher.

 

And there is another problem with the tube upgrade path.    Because military, law enforcement, and sportsman are moving to monocular (flexible and can be weapons mounted), thermal, and fusion systems (an possibly advanced and still classified CCD).

 

They are moving in such numbers that it seems like all or most of the tube production for high end PVS-7 tubes has stopped.

 

I looked for months and months for a high end PVS-7 tube in the new market, and turned up zero.

Eventually, I found the PVS-7 mentioned above on the used market (though it was like new).  I paid far more than what I have seen excellent PVS-7s sell for, but it was perhaps the very best PVS-7 tube I had seen for sale in all those months, and I became concerned that it would be more and more difficult in the future to obtain tubes with this kind of performance.

  

In theory at least it is possible to get a PVS-7 with similar (or better) tube specs than the Micro has,  but in practice, in my experience, it is getting hard to find them.


Edited by Eddgie, 24 February 2016 - 09:39 AM.


#14 Eddgie

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Posted 24 February 2016 - 09:53 AM

 

If I were to to make a comment that may be a touch negative, but recognizing the distinct advantages of this tech for astronomical observing for us amateurs, it is simply the notion that the image is, to my eyes at least, unnatural. 

 

Realizing that you are looking at a phosphor screen is different for sure. I recently tried the Mallincam and didn't like it. But, Mallincam was more like using a computer, and was not real-time. I am hopeful NV will be more like using a regular optic (despite the phosphor screen).

 

OTOH, NV gets you the infrared part of the spectrum you can't normally see. Highly unnatural, but sounds like a bonus to me.

 

 

My original interest in night vision was not for astronomy per se, but rather for use when I was out in the country doing astronomy.      I wanted to be able to see what or who was around me.  Some of the places I go are public places, and you never know who is sharing them with you.    

 

Maybe it is my old Marine Corp habits that demand that I keep situational awareness. While it might be politically incorrect to say so, I do have a CFL, and I even my girlfriend who is anti-gun asks if I am going to take a handgun when I observe, and when I go to some spots where there is some drive through traffic, I do.   

 

That was actually my original motivation.   I wanted to survail my surroundings. 

It was the forums here that promted me to consider night vision for astronomy.

I too thought that viewing the sky by way of a phosphor screen would be a bit unnatural.   

 

The first time I held the NVD Micro (my first device.. I wanted a PVS-7, but NVDepot could not get me a PVS-7 with ULT tube) up to my eye and looked though it, I was so freaking amazed with the view that I gasped.

 

I was standing in my light polluted yard in central Austin Tx on a very clear summer night, and when I looked up, I could see the Milky Way!    

 

The sky was so full of stars and the area in and around Sagittarius was so rich and detailed that I never even noticed the small apparent field of view or the green.   I just could not get over how much I could see!!!!

 

And when my H-a filter arrive and I put it on and saw North American Nebula on my first try on a regular not so clear summer night, it was pretty magical.  But it was even better than that because next to North American was the Gamma Cygni nebula complex that I had never even realized existed before.

 

This is one of those crazy things about NV.    Not only are some of these nebula very large, but the 40 degree true field shows you that they are often not alone.   Where there is one nebula, there is often another nebula, and being able to see multiple nebula in the same true field is something that is not really (to my own limited knowedge) possible in just about any other way.

 

I never even think about the fact that I am looking at a screen.

It does not feel that way.  It feels more like I am looking though a green filter.



#15 charotarguy

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Posted 24 February 2016 - 11:03 AM

 

 

If I were to to make a comment that may be a touch negative, but recognizing the distinct advantages of this tech for astronomical observing for us amateurs, it is simply the notion that the image is, to my eyes at least, unnatural. 

 

Realizing that you are looking at a phosphor screen is different for sure. I recently tried the Mallincam and didn't like it. But, Mallincam was more like using a computer, and was not real-time. I am hopeful NV will be more like using a regular optic (despite the phosphor screen).

 

OTOH, NV gets you the infrared part of the spectrum you can't normally see. Highly unnatural, but sounds like a bonus to me.

 

 

I never even think about the fact that I am looking at a screen.

It does not feel that way.  It feels more like I am looking though a green filter.

 

I am a complete newbie compared to Eddige, cnoct, jdb_astro, von******** (apologies to him, couldnt spell it correctly), outofsight, Doug, Ray and other fine people over here. I had similar concern about green color but when I saw M42 with NVD micro through Orion 10" XT scope with HA filter my jaw just hit the floor, I couldnt believe the details I was seeing in real time and at no time my mind thought that I was seeing it in green color, my concerns quickly dissipated.  And this was viewed from the light pollution mecca - near NYC (live on the right on the other side of the Hudson river).



#16 dan_h

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Posted 24 February 2016 - 12:01 PM

From what I can determine, the PVS-7 is restricted export. Not available outside the USA.

 

dan



#17 desertlens

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Posted 24 February 2016 - 12:17 PM

Eddgie, NV for astronomy is obviously interesting but expensive. A lowball question: Is there any point in using anything less than a Gen III system at an entry level?



#18 Jeff Morgan

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Posted 24 February 2016 - 12:28 PM

And there is another problem with the tube upgrade path.    Because military, law enforcement, and sportsman are moving to monocular (flexible and can be weapons mounted), thermal, and fusion systems (an possibly advanced and still classified CCD).

 

They are moving in such numbers that it seems like all or most of the tube production for high end PVS-7 tubes has stopped.

 

I had just assumed that the intensifiers tubes were the same physical dimensions, and therefore interchangeable. Apparently this is not so?



#19 JumboFlex

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Posted 24 February 2016 - 01:55 PM

From what I can determine, the PVS-7 is restricted export. Not available outside the USA.

 

dan

 

I was wondering about this as well. Canadian websites do list the gen3 tech though and it appears it is available for public purchase. Could be wrong as I haven't looked into it beyond a casual browse. Other countries no idea. 



#20 Eddgie

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Posted 24 February 2016 - 06:41 PM

Eddgie, NV for astronomy is obviously interesting but expensive. A lowball question: Is there any point in using anything less than a Gen III system at an entry level?

 

Gen 2 does not have the same IR response as Gen III, so you would not get the same nebula performance.

 

On star clusters, if you use averted vision, you can generally see any star that you could see in a Gen II tube, but it will be pretty easy to see those stars in the Gen II tube



#21 Eddgie

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Posted 24 February 2016 - 06:51 PM

 

And there is another problem with the tube upgrade path.    Because military, law enforcement, and sportsman are moving to monocular (flexible and can be weapons mounted), thermal, and fusion systems (an possibly advanced and still classified CCD).

 

They are moving in such numbers that it seems like all or most of the tube production for high end PVS-7 tubes has stopped.

 

I had just assumed that the intensifiers tubes were the same physical dimensions, and therefore interchangeable. Apparently this is not so?

 

 

I hope I have the explanation right, but I know the tubes are different in many ways.

 

The PVS-7 has a more complex optic and because of this it needs a non-inverting tube.

 

The monocular type systems (like the PVS-14) uses and inverting tube.  

 

(I might have that backwards, but one type inverts, one does not).

 

Also, the standard PVS-7 does not have any gain control.    the devices with gain control have a "pigtail" flat cable that plugs into the frame of the monocular and this goes to a gain control knob.   The PVS-7 tube has no external controls other than on/off.  It uses automatic brightness control to change the brightness of the view, so does not need a gain control (but gain control can be a positive because it allows you to tone down noise).

 

I hope I have the explanation right, but the tubes are in fact different and won't interchange (they are different physical lenghts I think).



#22 Eddgie

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Posted 24 February 2016 - 07:00 PM

 

From what I can determine, the PVS-7 is restricted export. Not available outside the USA.

 

dan

 

I was wondering about this as well. Canadian websites do list the gen3 tech though and it appears it is available for public purchase. Could be wrong as I haven't looked into it beyond a casual browse. Other countries no idea. 

 

 

 

US Gen III can be exported but only if the figure of merit (FOM) is something like 1300 (Not positive on this number).  

 

The FOM is the signal to noise ratio times the resolution.

For example, a device with a signal to noise ratio of 21 and a resolution of 64 lines per millimeter would have an FOM of 1344. 

 

This would limit the export of later Gen 3 tubes.

 

Now, Photonis in Europe sells tubes like the XD4 that are better than some US Gen 3 tubes and can produce some amazing views.  Expensive in Europe, but what isn't?

 

Here is a youtube video done by Cnoct, one of our forum members.

I should say that this is THE video that made me realize the potential of NV astronomy. 

 

This is what the Milky Way looks like using a Mid range PVS-7 under moderatly dark, clear skies, but this is a Photonis tube, and these are often available outside of the US (and there are better tubes than this)..

 

https://www.youtube....h?v=6-aJ7ab1hYA

 

Amazing...



#23 Eddgie

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Posted 24 February 2016 - 07:08 PM

If you view the above video, do so in full screen...

 

Cnoct has a lot of videos posted on Youtube.  Search "Carpe Nocturnum night vision astronomy"   

 

JDB_astro has a bunch too.   

 

Cnoct's videos were the ones that made me see the promise of NV astronomy.  JDB_astro's videos were mostly posted after I was already in.

And everyone will tell you that the view in person is better than the cameras used can capture.

 

Jay did some 30 second exposures of galaxies using a white phosphor tube (not a PVS-7) and the results were pretty great.

 

Visible in EAA forum.



#24 Eddgie

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Posted 24 February 2016 - 07:13 PM

Horse Head at 8x...

 

Sky is dark where he is, but I can see it from my front yard in central Austin, though not this bright.

 

Easy with the PV-7 stuffed into the 12" dob even from my light polluted back yard...

 

https://www.youtube....h?v=pqw0TWwKqlo



#25 BKSo

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Posted 24 February 2016 - 08:27 PM

I'VE got an idea for you, Eddgie. Voigtlander sells a 10.5mm f0.95 lens for micro 4/3 mounts. You can adapt to c-mount and enjoy some 0.4x hyper vision:) :) :)


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