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Night Vision Astronomy 2015: Three Perspectives

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#1 The Ardent

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Posted 07 January 2016 - 01:31 PM

Night Vision technology is a powerful tool to enhance observing. Like any observing method, it had its advantages and drawbacks. Three Cloudy Nights members offer their experience.

Click here to view the article
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#2 StarMike8SE

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Posted 08 January 2016 - 09:41 AM

Great review and a lot of great information.  Thanks for posting


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#3 Jeff Morgan

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Posted 09 January 2016 - 02:44 PM

Ever larger and faster mirrors are a financial, logistical, and thermal dead-end for me, NV sounds very tantalizing.



#4 The Ardent

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Posted 09 January 2016 - 10:33 PM

Jeff

Thursday night I observed, for the first time, four galaxies 1/2 degree south of Castor: IC 2193, 2194, 2196, and 2199. They were all easy with night vision in my 18" dob. Now consider the conditions: in a red zone Bortle 7 per Clear Sky Chart, 90% humidity, and direct glare from 4 streetlights. 

These are targets I would never even consider observing from my backyard with normal eyepieces. 



#5 Doug Culbertson

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Posted 10 January 2016 - 05:24 PM

 Good article!

 

A few years ago I had the priviledge of observing through a Collins I3 and was blown away. NV has been on my mind ever since then.

I currently live in what used to be a blue/green zone that has degraded to a yellow zone at best as the city moves closer. As faint fuzzies get fainter and fuzzier here I have been thinking about NV more and more. Thanks in no small part to the EAA forum and the guys who wrote this article, I just bought a used PVS-7 with very good specs. While expensive, it is a whole lot less expensive than buying land in a darker area, as we had been considering.  I am looking forward to more years of observing from home thanks to this technology. 



#6 DuaneS

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Posted 10 January 2016 - 05:24 PM

Great review. I viewed The Ardents night vision set up last fall at the Staunton River star party. I was very impressed. I kept leaving my 30" scope to go over and peek thru his. He brought the setup over to my scope and we tried an experiment. We went to SH2-188 with an eyepiece and we barely noticed a wisp. We put in the Night Vision setup and there it was in full view. Lots of fun. I may have to get one of those :-)

 

Duane



#7 Jeff Morgan

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Posted 11 January 2016 - 02:10 PM

A question to the authors, as trailblazers in this application:

 

What is the outlook on using the NV tube afocally? That is, using some type of bracket and mounting it to an existing eyepiece.

 

I recall a thread on this some months ago, with the speculation that a quality zoom eyepiece could be a winner since it would allow an easy and fast method of changing image scale (I do own a Leica ASPH). Any updated news?

 

In addition to be able to vary effective magnification, my thinking is this method may be more favorable to the slower focal ratios of my scopes (f/7, f/8.5, and f/9). At the eyepiece, the device really shouldn't be able to tell if the optics are f/1.2 or f/22 should it?



#8 The Ardent

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Posted 11 January 2016 - 05:47 PM

:shrug: Those answers are way above my pay grade. I've only been at this for a few months.  :scratchhead:

I can't say what works for me will work for you. I'm my case, the device is the eyepiece. I believe my success is due to having a fast large aperture scope. I applied night vision to what I was already doing and familiar with, and it works. 

 

I think night vision now is far more accessible than in the past. I remember 10-15 years ago the ads for the Collins I3 eyepiece (an observing buddy has one ) About 5 years ago there were some articles about the BIPH, but nothing lately. 



#9 Vondragonnoggin

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Posted 11 January 2016 - 06:33 PM

A question to the authors, as trailblazers in this application:

 

What is the outlook on using the NV tube afocally? That is, using some type of bracket and mounting it to an existing eyepiece.

 

I recall a thread on this some months ago, with the speculation that a quality zoom eyepiece could be a winner since it would allow an easy and fast method of changing image scale (I do own a Leica ASPH). Any updated news?

 

In addition to be able to vary effective magnification, my thinking is this method may be more favorable to the slower focal ratios of my scopes (f/7, f/8.5, and f/9). At the eyepiece, the device really shouldn't be able to tell if the optics are f/1.2 or f/22 should it?

 

Jeff,

 

  I am using a Baader Zoom for afocal viewing like you mention, but you need to start with relatively fast focal lengths to begin with to keep the image bright with less noise and scintillation. I wouldn't recommend slower than F/7 and preferably faster. I found using the Baader Micro-Stage II click stop digiscoping adapter works very good using a Night vision depot Micro Monocular coupled to the Baader Zoom. There is a thread on it in EAA forum started by me. The Image Intensifier does care about focal ratio still but not to the extent described in afocal imaging with a camera wiki. It sems to work more as you suggested - like a teleside converter, but cannot confirm that is the exact behavior until I make more comparisons. There is some dimming with increased magnification.

 

The NVD Micro has a 28mm ocular (approx). The Baader zoom is 24-8mm, so quite a bit more magnification and attaching the Micro Stage II clamp to rotating part of the zoom allows for a 180 degree twist through the magnifications. This resulted in greatly increased magnification without darkening the image or increasing scintillation as much as using a 2x barlow, but at the expense of eyepiece aberrations also coming through the Micro such as EOFB which was very noticeable after image intensifier amplified the view. Not so bad that I won't use it again though. To increase image scale as much as it did with the zoom in my 120ST would have required a much longer focal length (thereby increasing focal ratio if same size scope objective is used) or larger aperture with focal ratio still fairly fast. Neither of which is desirable to me. I am a small scope enthusiast, so it has to work with the smaller scopes I have. I had good success so far but have only had the setup out three times and some more comparisons to do, but looks to be a promising setup.

 

I don't think it is possible to attach the PVS-7 using one of the handy digiscoping adapters, but maybe some adapter could be made or bought. I use the Micro Monocular for this as it is perfectly suited right away with no extras needed.

 

Here is the thread on it - http://www.cloudynig...ro-afocal-work/


Edited by Vondragonnoggin, 11 January 2016 - 06:35 PM.

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#10 chemisted

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Posted 13 January 2016 - 08:09 PM

These are good articles and reflect the excitement possible with gen 3 equipment.  I have used a Collins I3 for over a dozen years from both light-polluted and dark sky sites.  I can not imagine living without one.  My largest scope is 10" but when viewing a favorable target it behaves as if it is 3x that aperture.  The initial price may look high, but when amortized over decades it really is inconsequential.


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#11 TOMDEY

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Posted 14 January 2016 - 10:56 PM

Thanks for the great article and now discussions.  I posted "elsewhere" brief comment regarding Night Vision at 1x with very little response.  Anyway, about two months ago I got TWO Gen3 Micros with 12nm pass H-alphas  - turned them ON and just hand-held one to each eye. My life will never be the same!  Totally unexpected was that at matched 1x ... It's like looking thru an enhanced H-alpha Window --- doesn't feel like binoculars or electronic cheating vision at all !  Honest: I am able to SEE the Horsehead (as a very small but distinct "notch").  And the Milky Way is just Loaded with obvious Ha features all over. North American, Pelican, California, Gamma Cyg butterfly-shaped thing, Rosette, Barnard's Loop --- all that stuff and much more just blazing across the sky.  I tried left only, right only and both. With two completely separate but matched I3s one thing is patently obvious:  Two is way better than one, WAY better.  I believe several things contribute to the enhancement (perceived brighter, better contrast, resolution, far less noisy): 1) The usual bino advantage - we have two eyes and the feeling of reality requires both. 2) The scintillation twixt L/R is completely uncorrelated - so brain effectively  filters it out. 3) The brain co-adds the correlated info and completely convincing; it looks twice as bright with both eyes! 4) Restatement of #3 applies also to far better contrast perception. 5) Both sample different atmospheric columns (to each field point) so uncorrelated atmospheric scint is effectively filtered out (ignored) by Visual cortex. 6) Ditto that regarding uncorrelated imperfections in the eyes (floaters, shot noise, neural path noise, blind spots, aberrations, etc.) Bottom line is - astounding views!  I also used (mono) on my 29-inch Dob.  Holy Cow!  The Horsehead looks like the photos (structure, brightness, resolution).  M42 is so bright I sampled it only briefly so as to not damage the tube!  The fluffy tendrils way out show magnificently.  Technical:  One thing that pleased and somewhat surprised me:  Because each side is operating at accurate 1x, it is not at all critical to have the two intimately aligned.  Just hand held one in each to each eye and the images merge just fine!  Honest - It feels just like looking thru a window to the Universe.  So I'm all excited and hooked.  Next:  I have JMI RB16s and just recently amended custom - very weak, 1.1x - Barlows to bring the two I3s parfocal with my Panos and Naglers.  Haven't had a favorable night yet but expecting spectacular views.  My background includes working in Visual Science at the U or Rochester (NY).  Well, I'm going to read the article more slowly now.  Thanks again!  Tom Dey


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#12 Perseus_m45

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Posted 19 January 2016 - 01:16 PM

Has anyone tried NV on close doubles ?



#13 The Ardent

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Posted 19 January 2016 - 04:49 PM

My experience: Not really the best for close doubles. Good for multiples with faint components, like 14 Aur or 59 Cyg.

With my dob, the night vision device gives 61x and 0.65 deg FOV. Looking at M81, there are two close doubles to the SW. Struve 1387 is easily split at 9", while Struve 1386 is not resolved at 2"

#14 petert913

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Posted 22 January 2016 - 04:04 PM

Check this YouTube video out.  Very nice examples

 

https://www.youtube....h?v=SBFEjSl5nI8


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#15 TOMDEY

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Posted 22 January 2016 - 06:51 PM

Thanx for the link, Peter. That is well-done and certainly looks a lot like it feels to use visually. I do note that my vis I3 shows notably more "pin-point" star images though. Not sure why. Maybe the foreoptics or cam focus in the video? When I had done video years ago with a Collins - same problem. Video not as good as looking thru.  Tom Dey


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#16 Bob S.

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Posted 27 January 2016 - 08:44 AM

It is nice to see that image intensifiers are getting some newly awakened press. Since the early days of Bill Collins putting out the I3 image intensifiers, many of us have been enamored with the views. My first views through one were from a neighboring 12" telescope at a Winter Star Party in about 2003 when the owner of a Collins asked if I wanted to see the Horsehead Nebula. I was shocked with what I saw. Well, about 6 or 7 image intensifiers later, I am still a big fan of the device and have a customized Micro IIE. Bill Collins did not have the mil-spec quite right in using a TeleVue magnifying lens that was only 7x whereas the military has found that magnifying the photocathode tube views x12 is more optimal. I learned this after being in contact with one of the country's leading experts on night vision devices who happens to live in Hawaii and he sent me a Micro IIE to compare to my Collins. The Micro showed me just a bit more contrast and better views and I sold my Collins I3 at the time. He used to actually jog at night with a binocular night vision device. They are a great compliment to both conventional eyepieces and astrovideo cameras and bridge the gap between the two genres very nicely. One night, about 5 years ago, I aksed Al Nagler if he would like to see the Flame Nebula and the Horsehead nebula in one of his TV NP127's. He was delighted with the views since he had never seen those objects through his own 5" refractor.


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#17 grao

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Posted 27 January 2016 - 10:02 PM

Is there a color version?



#18 TOMDEY

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Posted 28 January 2016 - 01:27 AM

Hi grao, regarding color: The gallium arsenide photocathode responsivity peaks in the red/NIR spectral range. And the phosphor screen is plain greenish or white. One could theoretically reconstruct (spectrally-shifted) color...but would be complex to say the least. The closest I have seen in a mil-spec device is ITT combined NV + Thermal. The NV is green and the thermal is orange. Those signature Fused colors are vivid because of the color contrast. Mil utility is obvious. The 1x monocular was amazingly compact, rugged and ... $15,000. I fell in love with it and then handed it back. Not really for astronomy, although I expect meteors would look amazing.  Tom Dey



#19 grao

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Posted 02 February 2016 - 08:29 PM

Thanks Tom- I guess a close approximation would be a Mallincam hooked to one of those eyeglass monitors!



#20 Jeff Morgan

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Posted 05 February 2016 - 10:31 PM

As I contemplate where NV could fit in, one natural fit comes to mind - the owners of large Dobs. The reasons:

 

1) Already own "fast" optics;

2) Interested in "going deep"; and

3) A demonstrated propensity to spend money.

 

I am getting way ahead of myself, but I think the question is a good one for those NV gurus who have "been there done that".

 

Q: Given the sensitivity of NV to the longer wavelengths, would the user of a truss dob experience artifacts (such as sky brightening) from his own body heat?



#21 Eddgie

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Posted 06 February 2016 - 09:25 AM

I use both my PVS-7 D and my NVDepot Micro in my 12" open truss dob from my back yard with no problems at all.

 

These devices do not really see bad effects at all other than at some angles the glare from the back porch light can get into the secondary box and cause glare.

 

I leave the porch light on though (it is on a dimmer and is a down-light so is somewhat baffled) because one of the great things about using night vision gear is that you don't have to stay dark adapted, though the automatic brightness control on the device will greatly dim the image if you are really out in the dark, so you do get partial dark adaptation, and if you are using a monocular, one eye will get fully dark adapted.  This was supposed to be one reason the military went to monoculars (one eye would always be full dark adatped for better situcuational awareness... At least that is what people say, but I think it was because it is smaller and lighter, sharper, can be mounted on a rifle, cheaper to make, and has a slightly sharper image).

 

Anyway, I use mine on an open truss dob and have absolutely no problem.


Edited by Eddgie, 06 February 2016 - 09:27 AM.


#22 Eddgie

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Posted 06 February 2016 - 09:32 AM

Should say this too... In the Comet Cather, it is a bit different story.  This scope does have problems with distant light getting inside the OTA.  I need to make a very short dew shield type baffle for this one.  Mostly it is OK, but I am in the habit of taking it outside and holding cradling it in my arms to wander down the street with it so I can get better vantage points closer to the horizon.

This scope clearly is getting off axis light spilling in.

 

Now maybe if I could walk down the street with my 12" dob in my arms I would have this problem too,  but since I can't do that, I don't have that problem.

 

This means that if there is any light source near the horizon where light can get into the tube, it could be a problem so I can't say an open truss will be completely OK because it could be that some light from somewhere could get in but as a rule, I don't have any problem at all.

 

One last thing.  With the NV in the Comet Catcher, I see stars that I struggle to see in the 12 dob using averted vision.  This means that walking down the street with the comet catcher in my arms is like carrying my 12" dob.

 

It is crazy good stuff.

 

I have sold off pretty much all of my high end scope stuff to go NV and have not regretted it.  I use the NV stuff far more often and see far more with it than ever.

 

I do more and more of my observing at very low power, but when I plug it into the dob, it is a major wow.  Like doubling the aperture.


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#23 Jeff Morgan

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Posted 15 February 2016 - 02:16 PM

An interesting question comes to mind for the Ardent, as well as other fast scope NV users:

 

1) For Newtonians, Paracorr, or non-Paracorr?

 

Also, I am guessing the integrated eyepieces in NV devices are "simpler" designs, not the "fully corrected" eyepieces the slick glossy advertising tells us we must have for a satisfactory viewing through a fast telescope.

 

2) How do NV eyepieces do at the faster focal ratios? 



#24 Doug Culbertson

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Posted 16 February 2016 - 02:30 PM

Jeff,

 

I have only used my PVS-7 once in the 11" f/5, and that was sans Paracorr. Coma was evident in the outer 20% of the fov, maybe a bit more. I was so mesmerized by the view that I didn't really notice the coma at first! Next time out I will try the Paracorr to see how that works out.

 

I think that the eyepieces are most likely a simpler design, given the 40° or so fov. FWIW, that 40° seems really wide when observing at 1x! they do seem to be pretty well corrected though.

 

My fastest scope is f/5, and I loved the views. I may actually end up with a focal reducer to see how that works out, as the Horse Head was pretty much in my face at f/5, and I would like to try out a bit wider fov in the scope.

 

Keep in mind that I am probably the most recent NV astronomy convert around, so take my experience for what it's worth.



#25 TOMDEY

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Posted 14 March 2016 - 05:56 PM

Catching up here: Ummm ... regarding coma: the NV field is small - gallium arsenide photocathode is only 18mm, so coma of the feed optics will generally not be problematic at all. But even the good integral "eyepiece" (actually a multi-element magnifying glass) renders the field edges not so good unless your eye is very well centered. Some custom mil applications use bigger photocathodes and/or flaring fiber optic image inverter - but those are very $$$. PS I've now used my Micro IIEs a lot and love them. So much so --- that I stare at my collection of Naglers and Ethos - and wonder why I have so many. BTW - A machinist friend modified a shorty barlow to fit the Micro. That's the only way to get parfocal 2x. That helps on close doubles a LOT! Otherwise, the NV is "stuck on" low mag (approx equiv to mag of a 25mm eyepiece).  Tom Dey




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