Jump to content

  •  

CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

Photo

Night Vision Intensifying Eyepieces

  • Please log in to reply
336 replies to this topic

#51 Sarkikos

Sarkikos

    ISS

  • *****
  • Posts: 30926
  • Joined: 18 Dec 2007
  • Loc: Per sylvam ad astra

Posted 20 March 2018 - 02:01 PM

For me the choice is clear. With a 4-5" scope in my white zone this was just a faint fuzz with averted vision. Switch out the Ethos for the NV eyepiece and I increased my aperture > 2x and transported myself to a dark site.

 

Too bad CN butchers images so bad, the original cell phone shot is much sharper in the core, as was the visual view.

 

Expensive? Very. But value for dollar spent compared to other astronomy gear? I'd say it's way up there.

 

OK, so what globular cluster is this?  No pics without labels.

 

Mike


Edited by Sarkikos, 20 March 2018 - 02:02 PM.


#52 moshen

moshen

    Apollo

  • *****
  • Posts: 1286
  • Joined: 17 May 2006
  • Loc: San Francisco, CA

Posted 20 March 2018 - 02:11 PM

OK, so what globular cluster is this?  No pics without labels.

 

Mike

Sorry, that's M13 2s exposure on my iPhone X to the NV eyepiece. It's a faint smudge due to LP in my backyard but fully resolved with NV. The image scale is small because stars blur quickly if I barlow up without tracking.

 

I put up the photo less butchered by CloudyNights here: https://imgur.com/a/rgl5a


  • Sarkikos and Starman81 like this

#53 JakeJ

JakeJ

    Mercury-Atlas

  • *****
  • Posts: 2661
  • Joined: 31 Aug 2004

Posted 20 March 2018 - 02:37 PM

My cell phone pics I've posted on this thread are VERY close to what I see visually. Visually the view is even sharper and there is little to no noise (a manual gain control is a must - turning down the gain for a clean view) - if I took a video of it there would be a ton of noise. I also use an alt-az so even a 2s exposure blurs stars.

 

As an example if you tried to take a video of a bright object like M42 in a big scope with glass eyepiece the view is bright and very clean in person but trying to get a clean video that looks the same is near impossible. For the same reason there isn't going to be a video of NV that is representative. The photos show it better.

 

Both of these are with 5" aperture in a white zone. iPhone X with 2s exposure. This is about what I see in the eyepiece although the Monkeyhead view is slightly fainter than what you see here.

 

M38 & NGC 1907, 5" aperture, white zone

Monkeyhead Nebula, 5" aperture, white zone

 

What I am looking for is what has cutely been called "scintillation".  Video will show it - it is different than video noise.


Edited by JakeJ, 20 March 2018 - 02:38 PM.


#54 moshen

moshen

    Apollo

  • *****
  • Posts: 1286
  • Joined: 17 May 2006
  • Loc: San Francisco, CA

Posted 20 March 2018 - 02:47 PM

What I am looking for is what has cutely been called "scintillation".  Video will show it - it is different than video noise.

With manual gain control you can turn it down so there is little to no scintillation, that's what I've been trying to say smile.gif With the 2s exposure above, scintillation would have shown up as clear speckles.

 

I also sent you a link to my video where most of the noise seen is from the cell phone and there is little NV scintillation showing. With a very narrow Ha filter and gain turned all the way up there is very visible scintillation but I never view that way. That may be how NV with no manual gain look as they are adjusting brightness for typical non astronomy use and it's compensating for a nearly black scene. There is very little benefit with the gain all the way up I've found. With the gain turned down the SNR is actually higher (but fainter) and the view is clean. I've had many people only realize it was a NV eyepiece when looking at my view after I told them what it was. They didn't question it was anything but glass. Then they have to look again once I tell them.

 

In the end, you really just have to try one in person as difficult as that may be.


Edited by moshen, 20 March 2018 - 02:51 PM.

  • Starman81 likes this

#55 jeffmac

jeffmac

    Viking 1

  • -----
  • Posts: 797
  • Joined: 01 Aug 2014
  • Loc: Triad area, NC

Posted 20 March 2018 - 03:29 PM

Maybe I've missed some info along the way but how do the NV devices do at high magnifications? A lot of what I read is about what can be seen at 1x or 3x.



#56 Starman81

Starman81

    Soyuz

  • *****
  • Moderators
  • Posts: 3689
  • Joined: 06 Mar 2008
  • Loc: Metro Detroit, MI, USA

Posted 20 March 2018 - 03:55 PM

Good to see you back Syed!

 

One little serendipitous discovery while you were gone:

 

Just out of curiosity, I tried a H-aplha filter on M27. I wasn't expecting much since we all think of these things as O-III targets.

 

Turns out M27 and the next dozen or so PN's I tried that filter on all responded quite well. H-alpha (12 or 7) is now my go-to filter for PN's.

 

Thanks Jeff! About the performance of h-alpha filters on PNs, that's a nice development--I'll have to try it out. 


  • faackanders2 likes this

#57 Starman81

Starman81

    Soyuz

  • *****
  • Moderators
  • Posts: 3689
  • Joined: 06 Mar 2008
  • Loc: Metro Detroit, MI, USA

Posted 20 March 2018 - 04:05 PM

My cell phone pics I've posted on this thread are VERY close to what I see visually. Visually the view is even sharper and there is little to no noise (a manual gain control is a must - turning down the gain for a clean view) - if I took a video of it there would be a ton of noise. I also use an alt-az so even a 2s exposure blurs stars.

 

 

Moshen's pictures are a very good example of how things look through the image intensifier. If seeing those objects as nicely as his pictures have represented, from light polluted environs doesn't excite you, then NV observing is not for you, plain and simple.


  • moshen likes this

#58 Starman81

Starman81

    Soyuz

  • *****
  • Moderators
  • Posts: 3689
  • Joined: 06 Mar 2008
  • Loc: Metro Detroit, MI, USA

Posted 20 March 2018 - 04:20 PM

Maybe I've missed some info along the way but how do the NV devices do at high magnifications? A lot of what I read is about what can be seen at 1x or 3x.

 

I'm a little rusty, but I'll give it a shot...

 

The Image Intensifier (IIE) wants a fat, fast light cone for max image brightness. The faster the better. 

 

The IIE being discussed (Mod 3 C) is equivalent to a 26mm eyepiece. So in a typical 8" f/5.9 dob (1200mm f/l) that would yield a magnification of 46x used natively at f/5.9. Introduce a 2x barlow and now you have 92x but you are running at f/11.8. And from what I recall, doubling the focal ratio means you are only getting 1/4 of the light being delivered to the IIE. So, keeping the scope constant, higher magnifications (by barlowing the IIE) = narrower light cone --> more scintillation as the tube becomes photon starved. So magnification comes at a cost. 

 

If I'm wrong, I know I'll be corrected soon. smile.gif



#59 moshen

moshen

    Apollo

  • *****
  • Posts: 1286
  • Joined: 17 May 2006
  • Loc: San Francisco, CA

Posted 20 March 2018 - 04:57 PM

I've found magnification to work very well for high surface brightness or stellar objects (small galaxies, star clusters, globs, planetaries).  There are many who run at F10 or slower. For low surface brightness objects like large faint nebula then the faster the better.

 

Lockwood has a good demonstration of speed vs brightness:

 

http://www.loptics.c...ightvision.html


Edited by moshen, 20 March 2018 - 04:58 PM.

  • Starman81 and faackanders2 like this

#60 moshen

moshen

    Apollo

  • *****
  • Posts: 1286
  • Joined: 17 May 2006
  • Loc: San Francisco, CA

Posted 20 March 2018 - 05:36 PM

Moshen's pictures are a very good example of how things look through the image intensifier. If seeing those objects as nicely as his pictures have represented, from light polluted environs doesn't excite you, then NV observing is not for you, plain and simple.

I possibly have the worse light pollution of anyone reading this thread. I live only three miles from downtown San Francisco. bawling.gif



#61 faackanders2

faackanders2

    Fly Me to the Moon

  • *****
  • topic starter
  • Posts: 6056
  • Joined: 28 Mar 2011

Posted 20 March 2018 - 05:53 PM

Ken, it was a nice night. Glad to give you the opportunity to see what NV can do! It was my first time observing in several months (7+) and I was excited to get out. 
 
A few details I'll add:
 
- Scope was my ST120 (f/5) with 0.5x Antares focal reducer (2"), which from past testing, reduces the scope down to a very fast f/3.2 (not quite true 0.5x reduction), yielding a 2.7 degree TFOV and 15x magnification.
 
- Observing site was an orange zone site. I didn't have my SQM on hand but I would estimate only 19.5-19.7 SQM. So not 'dark' by any means, but better than our suburban backyards at least. 
 
- Filters used: Baader 7nm h-alpha, Baader 685nm Longpass
 
You do a great job recording your observations from memory. The highlights for me were:
 
- Barnards Loop was the best I have seen, mostly because Orion was setting very early when I got my NV unit last year.
- Horsehead --> first time observation for me! Flame was nice as well
- Orion Nebula of course, goes with saying. Chock full of detail!
- Best framed view of the Rosette
- Great telescopic view of the California nebula, that nearly fit in the FOV


I did use S&T Pocket Sky Atlas Jumbo for writing my observations (which were from memory).
HT34(NGC 2024)/IC434/B33 and HT30(NGC1981)/M42/M43/HT 31(NGC1980) almost looked like Chart B split in two no wonder it was so easy to pan to both regions.
C49 (NGC2237/38/46)/C50(NGC244) and HT38(NGC2264)/large nebula region almost looked like Chart E, which I would have liked to have sen if it were possible to see all the other clusters.
Wich they would have had other blown up charts for the othe bright/large NV H-alpha nebolous regions!

The California nebula was so long it actually too two fileds of view.

Ken

#62 faackanders2

faackanders2

    Fly Me to the Moon

  • *****
  • topic starter
  • Posts: 6056
  • Joined: 28 Mar 2011

Posted 20 March 2018 - 05:59 PM

I possibly have the worse light pollution of anyone reading this thread. I live only three miles from downtown San Francisco. bawling.gif

You took those images from San Francisco? Wow, these may be just the thing urban astronomers need vs. driving hours to get to just a moderate dark site.

#63 moshen

moshen

    Apollo

  • *****
  • Posts: 1286
  • Joined: 17 May 2006
  • Loc: San Francisco, CA

Posted 20 March 2018 - 06:04 PM

You took those images from San Francisco? Wow, these may be just the thing urban astronomers need vs. driving hours to get to just a moderate dark site.

All of them from my backyard. Defininitely not kidding when I say white zone.



#64 faackanders2

faackanders2

    Fly Me to the Moon

  • *****
  • topic starter
  • Posts: 6056
  • Joined: 28 Mar 2011

Posted 20 March 2018 - 06:40 PM

I'm a little rusty, but I'll give it a shot...
 
The Image Intensifier (IIE) wants a fat, fast light cone for max image brightness. The faster the better. 
 
The IIE being discussed (Mod 3 C) is equivalent to a 26mm eyepiece. So in a typical 8" f/5.9 dob (1200mm f/l) that would yield a magnification of 46x used natively at f/5.9. Introduce a 2x barlow and now you have 92x but you are running at f/11.8. And from what I recall, doubling the focal ratio means you are only getting 1/4 of the light being delivered to the IIE. So, keeping the scope constant, higher magnifications (by barlowing the IIE) = narrower light cone --> more scintillation as the tube becomes photon starved. So magnification comes at a cost. 
 
If I'm wrong, I know I'll be corrected soon. smile.gif

Probably also depends on how bright the object are (Magnitude density). M42, M31, Double Cluster, M44, M45, M11, M8, M13, M22 can most likely handle higher power.

I believe we spent 25% of the time with NV H-alpha with the telescope, 50% NV H-alpha 1x, and 25% NV 1x wide band LP.

Ken
  • Starman81 likes this

#65 faackanders2

faackanders2

    Fly Me to the Moon

  • *****
  • topic starter
  • Posts: 6056
  • Joined: 28 Mar 2011

Posted 20 March 2018 - 06:47 PM

Thanks Jeff! About the performance of h-alpha filters on PNs, that's a nice development--I'll have to try it out.

So planetaries look better with NV H-alpha than NV O-III? Must be because NV is more sensitive to H=alpha than OIII, whereas our eyes are more sensitive to OIII than H-alpha.

#66 faackanders2

faackanders2

    Fly Me to the Moon

  • *****
  • topic starter
  • Posts: 6056
  • Joined: 28 Mar 2011

Posted 20 March 2018 - 06:53 PM

With manual gain control you can turn it down so there is little to no scintillation, that's what I've been trying to say smile.gif With the 2s exposure above, scintillation would have shown up as clear speckles.
 
I also sent you a link to my video where most of the noise seen is from the cell phone and there is little NV scintillation showing. With a very narrow Ha filter and gain turned all the way up there is very visible scintillation but I never view that way. That may be how NV with no manual gain look as they are adjusting brightness for typical non astronomy use and it's compensating for a nearly black scene. There is very little benefit with the gain all the way up I've found. With the gain turned down the SNR is actually higher (but fainter) and the view is clean. I've had many people only realize it was a NV eyepiece when looking at my view after I told them what it was. They didn't question it was anything but glass. Then they have to look again once I tell them.
 
In the end, you really just have to try one in person as difficult as that may be.

I used to fly helicopters with PNV6(or PNV7) which had severe tunnel vision for flying and had extreme scintilization, but you could see good enough for flying.

Syed's Gen 3 NV eyepiece/monocular had an adjustable amplifier so you could tune down the scintilization to negligble or barely noticable. Extremely pleasing views!

#67 moshen

moshen

    Apollo

  • *****
  • Posts: 1286
  • Joined: 17 May 2006
  • Loc: San Francisco, CA

Posted 20 March 2018 - 06:56 PM

Not really.  Some just prefer to connect directly to the photons instead of looking at a glowing screen.  It's a preference, that is all.

I've looked through several and find I don't prefer them - it's not for everybody.

I think it's good to use a NV device that's newer than one produced a decade ago like the ones you tried before announcing an opinion - this is really true for anything really. 

 

I get the connect with photon directly thing too. I had this worry as well. But it really vanished once I used my NVD. I get the exact same reaction and feelings visually observing as with glass. I still like my glass and pop them in for a bright colorful cluster.  So it's another addition and as easy as switching any other eyepiece. I do think most find themselves starting to downsize their glass collection though.


Edited by moshen, 20 March 2018 - 06:58 PM.

  • JakeJ likes this

#68 JakeJ

JakeJ

    Mercury-Atlas

  • *****
  • Posts: 2661
  • Joined: 31 Aug 2004

Posted 20 March 2018 - 07:01 PM

I think it's good to use a NV device that's newer than one produced a decade ago like the ones you tried before announcing an opinion - this is really true for anything really. 

 

I get the connect with photon directly thing too. I had this worry as well. But it really vanished once I used my NVD. I get the exact same reaction and feelings visually observing as with glass. I still like my glass and pop them in for a bright colorful cluster. 

Sure, that's why I'm interested in seeing video of your device.  In the gen3 collins I found the "scintillation" quite distracting, as well as the "staring into a tv tube" feeling.  

I think I've made it very clear that I have only viewed through the Collins.


Edited by JakeJ, 20 March 2018 - 07:03 PM.


#69 Jeff Morgan

Jeff Morgan

    Voyager 1

  • *****
  • Posts: 11225
  • Joined: 28 Sep 2003
  • Loc: Prescott, AZ

Posted 20 March 2018 - 08:34 PM

Those images are 20-30sec exposures, so will increase resolution and decrease apparent noise.

 

Again, I would like to see a video from one of the newer ones to see if any better than a Gen 3 Collins, which I found akin to staring at a low-res green monitor screen.  

Video will show how much TV static these new ones have.  I am curious to see.   

 

The specs on tubes have gotten much better since the Desert Storm era. Also, L3 found a way to make the tubes without the thin film (which IIRC was aluminum oxide) which makes the contrast quite a bit better.

 

With the white phosphor Mod 3 gain turned down I can achieve a view virtually indistinguishable from a 26mm plossl. Only AFOV cues give it away.

 

And the current production is even better than what I bought two years ago. Clutch5150 made a post about them. Unfortunately the post vanished, perhaps a TOS issue since he is a vendor?

 

But I'm not a vendor, so I can tell you what I read: some of the new Omni VIII contract tubes are sporting S/N ratios in the low to mid 40's with 85 lp phosphors. And of course low EBI, which is important for astronomy. Military and law enforcement snaps most of those up, but they can be had with patience.



#70 JakeJ

JakeJ

    Mercury-Atlas

  • *****
  • Posts: 2661
  • Joined: 31 Aug 2004

Posted 20 March 2018 - 08:40 PM

 

 

In the end, you really just have to try one in person as difficult as that may be.

 

I certainly would like to,  Hopefully I'll get a chance to peer through one sooner or later.  I'm not about to purchase one on a whim to test, though - the white phosphor tubes have quite the price tag.


  • faackanders2 likes this

#71 Jeff Morgan

Jeff Morgan

    Voyager 1

  • *****
  • Posts: 11225
  • Joined: 28 Sep 2003
  • Loc: Prescott, AZ

Posted 20 March 2018 - 08:58 PM

Maybe I've missed some info along the way but how do the NV devices do at high magnifications? A lot of what I read is about what can be seen at 1x or 3x.

 

They can do very well.

 

If the device has a C-mount objective lens (like the Mod 3c), you thread the objective off and replace it with a nose piece. Then it goes directly into the focuser like a 27mm eyepiece. It can be barlowed like a regular eyepiece. One can also use a focal reducer.

 

If the device does not have a C-mount objective (like the PVS-14), you get the Tele Vue/TNVC afocal adapter. In simple (if not elegant) terms, it clamps on to the end of the eyepiece. If the host eyepiece has a shorter focal length than the NV device, it acts like a barlow. If the host eyepiece has a longer focal length than the NV device, it acts like a focal reducer.

 

About Speed:

 

Emmission nebula are very sensitive to speed. But even at Maksutov focal ratios, it has much greater sensitivity than your retina. Yes, you can see the HorseHead nebula with a 90mm Maksutov. The slow speed and aggressive line filter make it a grainy view though. It's just one of those things that is fun to do just because you can. In actual practice f/13.8 on nebula is not where you want to be. I found my f/9 Newtonian perfectly enjoyable though.

 

Stellar objects (i.e., clusters) and high brightness objects (some PN's and galaxies) are much less bothered by slower speed. In that same Maksutov, the NV eyepiece operating at 27mm thoroughly trounces a 22 Panoptic on open clusters.

 

NV users due tend to get on a speed quest, directly analogous the aperture quest conventional observers suffer from. So let me say this: The comparison is not the F/3 wonder mirror you don't own (yet grin.gif ), but rather the comparison with the NV eyepiece to your standard one.


  • Starman81 likes this

#72 Jeff Morgan

Jeff Morgan

    Voyager 1

  • *****
  • Posts: 11225
  • Joined: 28 Sep 2003
  • Loc: Prescott, AZ

Posted 20 March 2018 - 09:04 PM

So planetaries look better with NV H-alpha than NV O-III? Must be because NV is more sensitive to H=alpha than OIII, whereas our eyes are more sensitive to OIII than H-alpha.

 

Yep. The dominant line is OIII. But H-alpha is there and the NV sensitivity seems to make up for it with plenty to spare.

 

This little trick is working well so far, 12/12. I'm sure I will run across PN's where the line is too weak, then I will try unfiltered.

 

And I always have my Leica ASPH and NPB at the ready just in case. It's not an either/or choice guys.


Edited by Jeff Morgan, 20 March 2018 - 09:05 PM.


#73 Peter Besenbruch

Peter Besenbruch

    Fly Me to the Moon

  • *****
  • Posts: 7056
  • Joined: 21 Aug 2014
  • Loc: Oahu

Posted 20 March 2018 - 10:26 PM

I possibly have the worse light pollution of anyone reading this thread. I live only three miles from downtown San Francisco. bawling.gif

I think it's called fog. ;)


  • BinoGuy likes this

#74 Tyson M

Tyson M

    Soyuz

  • *****
  • Posts: 3834
  • Joined: 22 Jan 2015
  • Loc: Alberta, Canada

Posted 20 March 2018 - 10:31 PM

Too bad you cant ever get a Mod3 unless you live in the US. 

 

Thankfully, I think there are some high spec ones I could buy from Brandonoptics in Canada. Otherwise all you can get is a PSV-7 from GSCI


  • 25585 likes this

#75 faackanders2

faackanders2

    Fly Me to the Moon

  • *****
  • topic starter
  • Posts: 6056
  • Joined: 28 Mar 2011

Posted 21 March 2018 - 08:30 AM

Too bad you cant ever get a Mod3 unless you live in the US. 
 
Thankfully, I think there are some high spec ones I could buy from Brandonoptics in Canada. Otherwise all you can get is a PSV-7 from GSCI

I assume this implies if you are a US citizen and have a Gen 3 it can only be used in the US, and you can't take it accross the border or could you providing you brought it back accross the border. What happens is customs conficates it.
It would be nice to see the southern hemisphere with it LMC SMC etc.


CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.


Recent Topics






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics