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NV Out of Reach B/C of Cost?

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#1 Ouranos

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Posted 16 November 2017 - 08:23 AM

The amazing thing about telescopes is the quality you can buy for $500.  I totally get that the word "quality" is definable individually.  A person can choose to spend $2 - 5 thousand on a telescope or $2 - 5 hundred on a telescope and the view may be different - but not to the point that the owner of the less expensive scope believes their instrument is not worth looking through.  What I am struggling to say - NV monoculars sound very intriguing, but the price point does not have the same spread that telescopes do.  If you want one, you are going to have to pay up.  I am not debating whether it is worth it or not, I am asking if there is any expectation that the costs for the equipment, like telescopes, will come down and be more available for those who may not have $2 - 4 thousand to spend on a monocular.  And, if there is less expensive NV equipment available, is the experience of looking through them substantially different than looking through the typically priced monocular.   



#2 Frenchcreek

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Posted 16 November 2017 - 08:44 AM

I, too, have been looking closely at acquiring an image intensifier and am also distressed at the cost.  It seems to me that the technology of these tubes, in comparison to the far more complex and capable technologies in smart phones and high end digital cameras, doesn't justify the price.  Some of my other issues with "going night vision" would surely be tempered if the cost of entry were not so high.  $4K for a monocular and probably another $1K for filters and adapters, etc...  I'm having a hard time justifying the cost to simply try out the technology.



#3 Jeff Morgan

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Posted 16 November 2017 - 09:37 AM

$4K is a big leap of faith to be sure. And if you buy a new unit and decide you don't like it, you will take a hit selling it as a used item.

 

Ultimate Night Vision rents NV units if you're unsure. Also check with TNVC (the folks who make the Tele Vue NV adapter).

 

You could shop the used market. If you are patient and get a good deal and decide you don't like it, you can resell it and only be out shipping costs. If you check recent threads on this forum, a CN member just scored a Gen 3 monocular for under $900. Kind of exceptional, but it does happen.

 

And a used PVS-7 in good condition can be had in the $1,500 range almost every day.

 

But how to raise the money?

 

Well, many of us (myself included) have jobs where we can work a little extra for more money.

 

The economy is stronger than it has been in a long time. If you want it bad enough, take a temporary or part time job to get the money.

 

Or you could sell off something laying around the garage you don't use anymore.

 

Chances are if you have been in the hobby more than a few years, you have already accumulated a lot of equipment. Mounts. Telescopes. Accessories. Especially eyepieces. Once you see NV, you will realize what a poor investment dozens (and in some case dozens more) of eyepieces were. Sell all but three or four.

 

Whatever you do, definitely get in the game. I've been in this hobby for over 40 years and NV is the most amazing thing I have seen. NV is far more - easily more - significant than the Dobsonian Revolution.


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#4 bobhen

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Posted 16 November 2017 - 09:52 AM

What Jeff said.

 

I want to just stop people from dropping 6 to 10K on a large Dobsonian and say, have you even considered NV. What details do you think moving from a 10-inch Dobsonian to a 20-inch Dobsonian will show you? Of course I would most likely be hammered over in the reflector forum. But here’s a thought, how about keeping that 10-inch Dobsonian and purchasing a NV image intensifier? You’ll see many objects that are just impossible to see otherwise with any size scope. And isn’t that the fun and thrill of all this?

 

Also been in this for close to 40 years. Had a 15-inch Dob. Would not go back.

 

Bob



#5 Adun

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Posted 16 November 2017 - 10:06 AM

NV stuff is rather old technology, I think 3rd gen was used in desert storm.

 

My take is that the reason it's not "commoditized" as telescopes and eyepieces have been, is because NV tubes are controlled devices, export is restricted (I can't buy one), most likely manufacturing them requires some sort of government license, which probably requires strict controls.

 

Export restrictions reduce the market size, while the other controls increase costs, all this drives potential manufacturers away and raises prices. It's military use is the true reason why this decades old technology is so expensive, just like it did for refractors in the 1700s.

 

I guess we'll need CMOS starlight cameras to get so good that NV tubes become irrelevant in the battlefield (that or achieve world peace) for the price and restrictions to come down. Only then will these tubes be available for us non-US civilians.


Edited by Adun, 16 November 2017 - 10:12 AM.

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#6 Kevdog

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Posted 16 November 2017 - 10:32 AM

As mentioned, I scored the TSE Gen3 monocular for $820.   An exceptional buy!   I had offered $1200 in my bid and was extremely pleased.   I have seen one of these go before for $1200 "Buy it now" on Ebay.   They are out of production as far as I know, but they still surface from time to time.   I haven't yet got mine in a scope due to new equipment curse (maybe this weekend?) but I have had a chance to look through a few sucker holes.   It's pretty darn amazing.

 

Another thing that comes up often is after getting an NV device, people sell off a lot of their normal eyepieces.   You can often make up a good portion of the cost that way (or prevent future purchases).  

 

The reason they are so expensive is that they are built to high military grade standards.   Mine isn't even a military model, but it feels like I could use it as a weapon!   It's heavy and solid construction.   Even hunters (another big market) need devices that are durable and reliable.

 

I've thought about making an "astronomy grade" housing for Gen3 tubes.   A durable plastic body would lighten the load for telescope use and lighten the price too.  Maybe use a 27mm plossl eyepiece (interchangable) and add a c-mount on the front.

 

I also saw a link where a guy made his own NV device by mounting an NV tube in PVC pipe and attaching camera lenses and a spare eyepiece (maybe from a microscope).

 

It should provide views similar (in brightness at least) to a telescope 2x to 3x larger than you have, so even an 8" orion dob works about like a 16" or even a 24" for light gathering.   (You still don't get the resolution gain).  So buying an 8" orion for $500 and a NV device for $2000 is similar to an Orion 16" dob.    Buying filters for NV is similar to buying lots of eyepieces.   It's really just an adjustment of thinking that we're all getting used to!

 

That said, I can't wait to try my NV in my 18" dob.   Best of both worlds!



#7 Eddgie

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Posted 16 November 2017 - 10:35 AM

The modern NV device, from all that I have been able to glean, is a very difficult piece of technology to make.

 

The mircochannel plate is an 18mm wafer that has has millions of holes in it.  The fiber optic bundle in itself is a masterpiece of engineering.   

 

And it all has to be perfect (to demand top end price, no one is going to want to see a black spot in the view).    

 

I make no excuses for being a realist.   There are always forums posts that challenge the cost of things.  

 

  • Why do big Apos cost so much? Can't they build a $2000 6" Apo?
  • Why can't they build an 8mm to 24mm zoom with a fixed 68 degree apparent field of view and sell it for the price of a Hyperion zoom (because this is always the number one compliant about the Hyperion zoom)
  • Why do Televue eyepieces cost so much? ES Eyepieces don't cost as much!
  • Why do people wait 10 years for an Astro Physics Refractor and then turn around and sell it for more than they paid? The rotten Baskets.. How dare them. 

It is expensive and not everyone can afford or even get it, but that is true with oh so many things.  I wish everyone could, but I am to realistic to know that this will ever happen.   I can't afford a Bugatti, but I wish I could.  Why do they have to cost so stinking much though???


Edited by Eddgie, 16 November 2017 - 10:35 AM.


#8 Eddgie

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Posted 16 November 2017 - 10:45 AM

And to answer your question about the difference, a $1500 PVS-7 can do a lot of great astronomy, but it will not have the same contrast as a top end monocular.   Still, it can do a great job of opening up the sky.  A good PVS-7 is a lot better than nothing and I would rather have a good PVS-7 than any conventional eyepiece ever made.  


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#9 Rickster

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Posted 16 November 2017 - 12:32 PM

Even though the NV posts on the EAA forum tend to focus on the best available, you don't need to spend top dollar to get a NV device that will make a dramatic improvement in what you can see. 


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#10 sink45ny

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Posted 16 November 2017 - 12:55 PM

I live in the northern NY metro area if someone wanted a demonstration of a device I would be willing to show it at a club sanctioned star party or NV event.

 

People with scopes accepting 1.25" eyepieces could compare a before and after views easily.

 

When Al Nagler showed his device at NEAF there was a line to view his device with the makeshift star field.


Edited by sink45ny, 16 November 2017 - 01:06 PM.


#11 Frenchcreek

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Posted 16 November 2017 - 01:44 PM

A week of reading the enthusiastic NV threads by all of you guys - Eddgie, Kevdog, Bobhen, and Jeff, to name a few - and viewing the video and still image results of Cnoct and Jdb_astro are the stimulus for making me so interested in NV.  You've done a bang-up job of selling me; your enthusiasm is contagious.  I feel certain that I would enjoy NV.  But how much?

 

It's not a matter of having the money for a top end intensifier (I do), but a question of value for the money.  Millions of holes, Eddgie, are difficult, but what of the millions of transistors in the much less expensive tech all around us?  Having built hundreds of thousands of tubes for decades one would think the price might become much less expensive as it does in other technologies.  I suspect that Adun may have a good point.

 

Will I wish to sell off much of my equipment after starting down the NV path?  Some of the CN members suggest it is so.  Then I will have to sum up those losses to add to the expense of an intensifier.  An even more expensive proposition...

 

In order to avoid unanticipated headaches I nearly always avoid used equipment.  And I'd much rather buy the good stuff now to avoid being disappointed by lesser products and perhaps give up on NV out of ignorance.  So $4K+ is my number.

 

And I ask myself, for what?  Here my doubts and skepticism kick in.  Do I really want those photons I view so enjoyably through glass to be changed to electrons, amplified, and displayed to me on a little low-resolution screen?  In green?  In blue-white?  With the blotchiness and distortion I see on Youtube vid's produced with equipment one only dreams about?  (My views won't be that good.)  Do I want that artifice in my star-gazing?

 

Well, the answer may be "yes".  I don't want any bigger dob than my 8", nor a bigger apo than my 4.5".  Seeing more, if only on a tiny tv screen, may be worth the price of admission - as all of you who have written in response to this topic have happily concluded.

 

Thanks, sync45ny, for the offer to share.  But I'm in Kansas.  Thanks to all of you who have made suggestions and shared the wisdom of your experience.



#12 Rickster

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Posted 16 November 2017 - 02:41 PM

I understand your skepticism.  I felt the same way before I bought mine. 

 

The pics and videos don't even begin to do the real time view justice.  The difference is stunning, IMO.  You really do need to see it to believe it. 

 

You are welcome to look through mine, in Kansas.


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#13 Adun

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Posted 16 November 2017 - 02:50 PM

Millions of holes, Eddgie, are difficult, but what of the millions of transistors in the much less expensive tech all around us?

 

It's billions when it comes to transistors.

 

But I think there's a better comparison: Pixels.There's 8 million pixels in a 4K "UHD" TV. Each LED pixel emits light in one of millions of colors, with up to 100.000 to 1 contrast differences, and 0.1 Hz response times. You can get an UHD TV for under $400, and the views it provides are far superior from a PVS7 (just display a hubble picture in 4k and you'll see).

 

My point is that the economies of scale in producing components for TVs for everyone in the world, is what has enabled the prices of these flat TVs to fall so much over the years. Remember how much a Plasma TV used to cost just 10 years ago (thousands!). The same has happened for smartphones. Without economies of scale, prices won't drop.

 

Of course not that many people want telescopes as TVs or smartphones, but still, with telescopes now being more inexpensive than ever, the market for eyepieces has grown larger, there are new manufacturers in the game, and I'm guessing all that is playing a part in why we can now get something as good as the Meade 5.5mm UWA new for $100, or an ES82 for $150.

 

I don't think there's a true technical limitation preventing 18mm wafers with millions of holes and complex optic fiber interconnections become cheaper over the decades. It's the lack of economic incentives for manufacturers to tackle the problem. The fact that we amateur astronomers are few is one of them. The fact these are restricted export, controlled devices with military uses, is another.

 

The more I read the EAA forums, and the more I read about the most recent "Sony's new sensor", the more I'm convinced that the future of night vision will be CMOS made for the (huge market of) video surveillance industry.

 

Eventually a threshold will be crossed, a CMOS sensor will come with enough sensitivity and signal to noise that exposures of just 1 second will be enough for astronomical use, and those might become the recommended "best value" real time NV solution for observing.

 

I'd like to use a gen3 (or even gen2) device until that happens, but I'll have to make do with my current EAA camera until then.


Edited by Adun, 16 November 2017 - 02:54 PM.


#14 Rickster

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Posted 16 November 2017 - 02:51 PM

Oh, and to clarify.  The "screen" resolution is equal to or better than your eyes.  The real difference is that with NV you can see things that were previously invisible (previously zero resolution, if you will).  And if you are looking at dim objects, the image will appear gray, just like in a standard eyepiece, due to the limitations of your eyes (rods vs cones).  Since cameras don't have rods and cones, they reproduce the green color, even when faint.  Bright objects like M42, will appear green (or blue/white) but you probably won't even notice after a while.  If you want true color, EAA cameras are the way to go.  But it is a lot more complicated and doesn't have the real time wow factor.  I use both.  I rarely use glass eyepieces anymore.


Edited by Rickster, 16 November 2017 - 02:53 PM.

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#15 Eddgie

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Posted 16 November 2017 - 03:11 PM

I have no doubt that in time, chips will overtake vacuum tube technology, but it hasn't yet. 

I am getting older and can't wait for those miracles to appear. 

 

In the mean time, I have done the absolute most rewarding astronomy in my life in the last 2.5 year and I am thankful for the window on the universe that this "old" technology has given me. 


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#16 Adun

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Posted 16 November 2017 - 03:12 PM

Oh, and to clarify.  The "screen" resolution is equal to or better than your eyes.

 

I don't know about that, but for the record, the human retina has 100 million rods, so our (monochrome) resolution is 100 Megapixels.

 

Compare that to only five million cone receptors in our retina, which means our color vision has a resolution of just 5 megapixels which is just below UHD/4k.

 

The current best camera from the sensitivity point of view is the A7, with 27MP. Imagine someting with half the resolution, quadruple the sensitivity for $100.... one can dream.

 

Edit: $100 would be a tenth of the price, since the A7 costs $1000. Right now I'd rather get a NV tube than an A7 camera, but down the road there'll be an A7 descendant that'll just make more sense for astronomy purposes.


Edited by Adun, 16 November 2017 - 03:14 PM.


#17 Kevdog

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Posted 16 November 2017 - 03:14 PM

A week of reading the enthusiastic NV threads by all of you guys - Eddgie, Kevdog, Bobhen, and Jeff, to name a few - and viewing the video and still image results of Cnoct and Jdb_astro are the stimulus for making me so interested in NV.  You've done a bang-up job of selling me; your enthusiasm is contagious.  I feel certain that I would enjoy NV.  But how much?

 

It's not a matter of having the money for a top end intensifier (I do), but a question of value for the money.  Millions of holes, Eddgie, are difficult, but what of the millions of transistors in the much less expensive tech all around us?  Having built hundreds of thousands of tubes for decades one would think the price might become much less expensive as it does in other technologies.  I suspect that Adun may have a good point.

 

Will I wish to sell off much of my equipment after starting down the NV path?  Some of the CN members suggest it is so.  Then I will have to sum up those losses to add to the expense of an intensifier.  An even more expensive proposition...

 

In order to avoid unanticipated headaches I nearly always avoid used equipment.  And I'd much rather buy the good stuff now to avoid being disappointed by lesser products and perhaps give up on NV out of ignorance.  So $4K+ is my number.

 

And I ask myself, for what?  Here my doubts and skepticism kick in.  Do I really want those photons I view so enjoyably through glass to be changed to electrons, amplified, and displayed to me on a little low-resolution screen?  In green?  In blue-white?  With the blotchiness and distortion I see on Youtube vid's produced with equipment one only dreams about?  (My views won't be that good.)  Do I want that artifice in my star-gazing?

 

Well, the answer may be "yes".  I don't want any bigger dob than my 8", nor a bigger apo than my 4.5".  Seeing more, if only on a tiny tv screen, may be worth the price of admission - as all of you who have written in response to this topic have happily concluded.

 

Thanks, sync45ny, for the offer to share.  But I'm in Kansas.  Thanks to all of you who have made suggestions and shared the wisdom of your experience.

 

I was looking at new too and I think you could do quite well with this:

http://nvdevices.com...sion-monocular/

 

NVD Micro XLS-1 for $2599.   From what I've read I'm guessing you're not giving up much performance vs the top of the line $4000+ one.   Maybe 85% to 90% of a top of the line tube?   (Others can chime in here).  And the nice thing is if later you want to upgrade the tube, you can, and resell your old tube for a good hunk of the price.

 

I too was a "photons to my eye guy" and didn't want to view on a screen, but through an eyepiece.   The NV caught me as the experience is just like an eyepiece.   There is still the distinction that you're not catching the actual photons from the stuff far away, but those actual photons are electrically amplified in real time to give you the view.   I haven't lost that same feel, even though I've now got a much boosted view.   If the skies hold this weekend I plan to go galaxy hunting this weekend and rather than try and spot the faint detail I hope to study them in great detail!   Also gotta try comet hunting again and see more than just the nucleus!

 

At home I can see a faint fuzzy spot where Andromeda is.  Put up the NV even at only 2x and I see an extended object with edges.   Soon hope to have a 5x and 8x lens working so I can get even better detail.  This with a device I'm hand holding and can carry in a small 4" by 6" bag!  It is hard to describe because it's different than all the other telescope experiences I've had!



#18 Frenchcreek

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Posted 16 November 2017 - 03:17 PM

I understand your skepticism.  I felt the same way before I bought mine. 

 

The pics and videos don't even begin to do the real time view justice.  The difference is stunning, IMO.  You really do need to see it to believe it. 

 

You are welcome to look through mine, in Kansas.

Rickster,

I'd love the opportunity to look through your PVS-7 here in Kansas.  Can it be arranged?


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#19 chemisted

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Posted 16 November 2017 - 03:21 PM

Have you read my article in the July issue of Sky & Telescope?  I equated the views I get of globulars to the 40"  refractor at Yerkes and I am using only a 10" reflector.  This is with a first generation Collins I3 eyepiece that I have seen sell on the used market for <​ $1500.  I bought it 15 years ago and I continue to use it today.  Back then many of the same questions were asked about the technology and, I suppose, they will always be asked.  To answer any doubts you may have you simply have to look through one.  This year I picked up a used NVD Micro and, without a doubt, I think it is a wonder. That said, I wouldn't hesitate recommending an older eyepiece to anyone looking to get into the hobby.

 

Ed Mihelich



#20 Frenchcreek

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Posted 16 November 2017 - 03:41 PM

 

A week of reading the enthusiastic NV threads by all of you guys - Eddgie, Kevdog, Bobhen, and Jeff, to name a few - and viewing the video and still image results of Cnoct and Jdb_astro are the stimulus for making me so interested in NV.  You've done a bang-up job of selling me; your enthusiasm is contagious.  I feel certain that I would enjoy NV.  But how much?

 

It's not a matter of having the money for a top end intensifier (I do), but a question of value for the money.  Millions of holes, Eddgie, are difficult, but what of the millions of transistors in the much less expensive tech all around us?  Having built hundreds of thousands of tubes for decades one would think the price might become much less expensive as it does in other technologies.  I suspect that Adun may have a good point.

 

Will I wish to sell off much of my equipment after starting down the NV path?  Some of the CN members suggest it is so.  Then I will have to sum up those losses to add to the expense of an intensifier.  An even more expensive proposition...

 

In order to avoid unanticipated headaches I nearly always avoid used equipment.  And I'd much rather buy the good stuff now to avoid being disappointed by lesser products and perhaps give up on NV out of ignorance.  So $4K+ is my number.

 

And I ask myself, for what?  Here my doubts and skepticism kick in.  Do I really want those photons I view so enjoyably through glass to be changed to electrons, amplified, and displayed to me on a little low-resolution screen?  In green?  In blue-white?  With the blotchiness and distortion I see on Youtube vid's produced with equipment one only dreams about?  (My views won't be that good.)  Do I want that artifice in my star-gazing?

 

Well, the answer may be "yes".  I don't want any bigger dob than my 8", nor a bigger apo than my 4.5".  Seeing more, if only on a tiny tv screen, may be worth the price of admission - as all of you who have written in response to this topic have happily concluded.

 

Thanks, sync45ny, for the offer to share.  But I'm in Kansas.  Thanks to all of you who have made suggestions and shared the wisdom of your experience.

 

I was looking at new too and I think you could do quite well with this:

http://nvdevices.com...sion-monocular/

 

NVD Micro XLS-1 for $2599.   From what I've read I'm guessing you're not giving up much performance vs the top of the line $4000+ one.   Maybe 85% to 90% of a top of the line tube?   (Others can chime in here).  And the nice thing is if later you want to upgrade the tube, you can, and resell your old tube for a good hunk of the price.

 

I too was a "photons to my eye guy" and didn't want to view on a screen, but through an eyepiece.   The NV caught me as the experience is just like an eyepiece.   There is still the distinction that you're not catching the actual photons from the stuff far away, but those actual photons are electrically amplified in real time to give you the view.   I haven't lost that same feel, even though I've now got a much boosted view.   If the skies hold this weekend I plan to go galaxy hunting this weekend and rather than try and spot the faint detail I hope to study them in great detail!   Also gotta try comet hunting again and see more than just the nucleus!

 

At home I can see a faint fuzzy spot where Andromeda is.  Put up the NV even at only 2x and I see an extended object with edges.   Soon hope to have a 5x and 8x lens working so I can get even better detail.  This with a device I'm hand holding and can carry in a small 4" by 6" bag!  It is hard to describe because it's different than all the other telescope experiences I've had!

 

Thanks for the suggestion re the Micro, Kevdog and Ed M., but "in for a penny, in for a pound".  I can afford the better WP tube in the Micro or the Mod-3 C WP and hopefully be done with it.

 

By the way, can anyone tell me how the ITT tubes compare to the L3?  I ask because the NVD Micro uses the Pinnacle, Mod-3 the L3.  For astro use, is there a consensus preference?

 

I should also note that like you, Eddgie, I'm not getting any younger and waiting will do me no good.

 

Ed M: I must have missed your article.  NV wasn't on my radar then.  I'll make to sure to find it and read it pronto.

 

To all of you NV evangelists, I sometimes suspect you are a little like fishermen.  You know, about the fish you caught?



#21 Jeff Morgan

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Posted 16 November 2017 - 05:49 PM

NV stuff is rather old technology, I think 3rd gen was used in desert storm.

 

My take is that the reason it's not "commoditized" as telescopes and eyepieces have been, is because NV tubes are controlled devices, export is restricted (I can't buy one), most likely manufacturing them requires some sort of government license, which probably requires strict controls.

 

Export restrictions reduce the market size, while the other controls increase costs, all this drives potential manufacturers away and raises prices. It's military use is the true reason why this decades old technology is so expensive, just like it did for refractors in the 1700s.

 

I guess we'll need CMOS starlight cameras to get so good that NV tubes become irrelevant in the battlefield (that or achieve world peace) for the price and restrictions to come down. Only then will these tubes be available for us non-US civilians.

 

Computers were used in Desert Storm too. Performance has improved quite a bit since then. Same with NV, if not as dramatically.

 

But you are right on the economies of scale. At most the military might order in the low millions over a decade or two. Computer makers sell in the low millions every business quarter! And there are additional markets for the chip makers to sell to beyond computer manufacturers.

 

And I agree with you that CMOS cameras will undoubtedly overtake NV in terms of sensitivity and integration times so fast it will appear "real time". (And be in color.) But when? Ten months? Ten years? I don't know.

 

But I do know that it will not help me out this new moon cycle.



#22 11769

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Posted 16 November 2017 - 06:52 PM

I'm not exactly a stranger to astronomy or electro-optics though I've combined the two only over the last year or so. It's been, without a doubt, the most rewarding and fulfilling hobby pursuit I've gotten into over the years and even after blowing relatively obscene amounts of money (I'm cheap) on all sorts of NV goodies, my only regret is that I have not done it sooner. Being able to see things that the human eye just can't and being able to see them in real time is something I can't put a price tag on. Totally worth it. 

 

To the newcomers, patience pays off as well as doing some research. With a little digging, a PVS-7 can be found for under $1k (have two, one has a nice Omni 7 contract tube). A bit of homework really pays off in knowing what you're getting. A MOD-3C with optics and a good thin film tube can be had for ~$2k if one is patient. Harder now that the supply of ENVIS lenses dried up. I decided to bite the bullet and upgrade to a filmless tube with respectable specs and that is the only cost adder that I think is not fully justified. Tube is wonderful; the price/performance ratio just isn't there (2-3 times the price).

 

I went down this road after seeing Andromeda hovering overhead with PVS-5 goggles. Upgrading then to Gen 3 was totally worth it. Now comparing all my tubes from different contracts and with different specs, my recommendation to a newcomer would be that a "cheap" Omni 4 contract (or civilian tube with comparable specs) is the minimum necessary for the desired "wow" factor. With patience, an Omni 7 tube can be had for just a little more and is the best bang for the buck. I've never had the pleasure of looking thru the top notch filmless tubes some people have so that statement may change. When I'm hunting for a tube, 64lp/mm is minimum and I don't get distracted by a 72lp/mm tube. Would say a minimum SNR would be 25. More is better but from my own viewing impressions, I'd focus more on EBI. That's really where spec sheets come in, EBI. The max value for mil contracts (2.5) is way too high for my taste. EBI of 1 or higher annoys me. EBI is also one place where select older tubes can really shine; there's an observable correlation between higher PC values and higher EBI yet when choked down with especially slower optics, I find excessive EBI gets in the way first. 

 

As far as cost of the tubes, I'm sometimes surprised it's not more expensive. The manufacturing that goes into a tube exceeds what's required for semiconductor fab yet the market is many orders of magnitude smaller. Depending who one listens to, the yield that L3 or ITT had over any one run could be as low as 25%. Being ITAR controlled products destined almost exclusively for volume consumers with deep pockets drives the price up even more. 

 

Someone asked how L3 or ITT tubes compare. Up until a few years ago, ITT usually had a better reputation. L3 power supplies were sometimes misconfigured at the factory back then and judging from how the autogating (not required for astronomy)  is handled on L3 tubes from ~2010, the feedback loop constants could be improved, at least compared to ITT. After Harris bought ITT, the situation is different. L3 tends to have a better reputation nowadays. The internal build quality tends to be higher as well. Comparing a recent ITT tube to an L3 tube after removing all the potting, construction differences can be seen and the L3 build quality inspires more confidence. There are other details that I have not been able to verify first hand that would lead me to steering clear of ITT tubes made in the last few years unless the price is too good to pass up.

 

These are just my own impressions since getting serious about astronomy and NV about a year ago. Any and all clarifications and corrections would be welcomed. 


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#23 Eddgie

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Posted 16 November 2017 - 06:56 PM

Most of the PVS-7 tubes regardless of contract number were in the Omni IV or V performance range.  You really need to go off of the part number for the tube and not the contract number, or at least that is my understanding.



#24 Eddgie

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Posted 16 November 2017 - 07:30 PM

 

Oh, and to clarify.  The "screen" resolution is equal to or better than your eyes.

 

I don't know about that, but for the record, the human retina has 100 million rods, so our (monochrome) resolution is 100 Megapixels.

 

Compare that to only five million cone receptors in our retina, which means our color vision has a resolution of just 5 megapixels which is just below UHD/4k.

 

The current best camera from the sensitivity point of view is the A7, with 27MP. Imagine someting with half the resolution, quadruple the sensitivity for $100.... one can dream.

 

Edit: $100 would be a tenth of the price, since the A7 costs $1000. Right now I'd rather get a NV tube than an A7 camera, but down the road there'll be an A7 descendant that'll just make more sense for astronomy purposes.

 

The scoptopic (dark adapted eye) can only resolve about 3 arc minutes of apparent field. Below this size and a detail will not have a describable shape.

 

The photopic eye can resolve about 1.1 arc minutes of apparent field.

 

Now, keep that figure in mind.

The modern image intensifier can resolve 64 line pair per millimeter.  The tube window is 18mm,   This means that across the face of the tube, it can display 1152 line pair, or 2304 lines.

 

The apparent field of the tube is 40 degrees, so this means that one degree of apparent field will contain (2302 / 40 ) 50 lines for every apparent degree of true field, and if you divide 60 /50, you get 1.2 lines per minute of true field. 

In other words, the tube does indeed display material that is well matched to the resolution response of the photopic eye, and unlike the conventional astronomer, the night vision device lets the eye work at closer to photopic levels for brighter scenes, but just just like with conventional eyepieces, if the scene is dark and they eye is not working in photopic mode, the eye's resolution will not be able to resolve all of the data that the tube shows in exactly the same way the unaided eye can't see all of the detail in shown at the eyepiece, but a camera in afocal mode can capture. 

 

I doubt that this 64 line pair per millimeter was a funny coincidence.  Clearly the specification was to make the device show as much resolution as possible and not more than necessary.  Note that the military did not demand higher resolution over the life of Gen 3 optics than was called for in Omni IV.  

 

At least this is my understanding of the math.   The view in an image intensifier is about as sharp as the eye can consume and in fact, you see more detail working with image intensifier than you do with scotopic vision and a lot of that is because the image is brighter, resulting in the firing of more cones. The people that designed this stuff knew what they were doing.  Everything here has been highly optimized over three generations of devices.


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#25 Ouranos

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Posted 16 November 2017 - 07:36 PM

Thanks for all the responses.  I am going to be 60 in a month.  My neighborhood is slowly but surely being overwhelmed with light pollution.  23 years ago, when I moved here, the milky way was easy to see, I could make out the smudge of the Andromeda Galaxy and the Dbl Cluster.  All that has changed, especially as more and more outdoor LED lights are being used in our town and  neighbors are leaving lights on throughout the night - fear?  So, I am on the hunt for a way to cut through all the light and be able to see "stuff".  Everything about NV viewing sounds like just what I am looking for to continue my astronomy pursuit in my context.  But, the cost is in my way.  If I were to sell ALL of my astronomy equipment - I would still come short of the price of a new micro NV monocular.  (And, I consider my equipment at least average? - beauty in the eye of the beholder)  I am reading all I can - I don't understand all the talk about tubes and Gen 2 or 3.  But, I am very intrigued.




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