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

My two biggest concerns with NVD

  • Please log in to reply
15 replies to this topic

#1 D-zen

D-zen

    Lift Off

  • -----
  • topic starter
  • Posts: 8
  • Joined: 27 Oct 2022
  • Loc: SouthEast Europe

Posted 01 February 2023 - 09:48 AM

Before purchasing, I had two major concerns about purchasing an NVD
1. Would I mind a small FOV of 40 degrees?
2. Will the aesthetics of the star display bother me?

 

I found it challenging to clear both of these doubts just by reading online forums. An evening with NVD under the stars would solve my worries, but no one in my immediate or distant surroundings has such a device.

In the end, encouraged by the posts on this forum, I decided to buy 'blindly', the price is ridiculous :-), but it turned out to be my best investment in this hobby of ours!

 

So, for those who may be in a similar situation:

 

1. Small FOV?

 

I really enjoy the relatively large FOV of my Morpheus, Pentax, and even Panoptic eyepieces. I was truly afraid that those 40 degrees would be too little for me. What can I say, never but never does the view through the NVD seem cramped to me. I can't explain why, probably a combination of the amount of information in those 40 degrees and the long eye relief. Simply, for me personally, those 40 degrees are not a problem at all.
The NVD FOV has become so natural to me that recently I started using my Baader ortho eyepieces for DSO as well :-)

 

2. Aesthetics of the view compared to glass eyepiece?

 

Before buying, I saw on internet forums a lot of nice (processed) photos through NVD eyepieces, but also a lot of terribly bad photos and ugly green flashing videos :-) of NVDs in action. I wasn't sure what to expect.
When I inserted my new NVD (OVNI-M 2100) into the diagonal, at first glance, the aesthetics of the view were truly worse, but after a little use, I would even say that it is not so bad as different compared to glass.
So, first of all, NVD does not have the colors of the stars, but it also does not have the pinpoint brilliance and dynamics of the view through a quality glass eyepiece.

On the other hand, when in the 4-inch achromat, in bortle7, you see a resolved small M79 globular cluster at only 16 degrees ALT through the haze of the atmosphere, then the aesthetics somehow fade into the background. In my opinion, the best description of the image would be that the aesthetic is similar to those invented scientific photographic plates with black stars on a white background.

When I start observing the stars through the NVD, somehow I put myself in that beautiful-ugly 'scientific' mode where what you see is more important, not whether the object you see sparkles beautifully :-). And what is most important in my opinion, I really enjoy that presentation, even though it is somewhat worse. When I'm hungry for beauty, I put in Pan35 and turn to Pleiades or DoubleCluster.
One more thing to add, the overall image quality is much better in prime focus compared to afocal, it is also slightly better in the APO telescope than in achromat, so that should be kept in mind. All of this refers primarily to the aesthetics of the star display, the nebulae are phenomenal through NVD.

 

Of course YMMV.

 

Clear skies to all!

 

 


  • Jeff Morgan, GeezerGazer, bobhen and 7 others like this

#2 Jeff Morgan

Jeff Morgan

    James Webb Space Telescope

  • *****
  • Posts: 16,158
  • Joined: 28 Sep 2003
  • Loc: Prescott, AZ

Posted 01 February 2023 - 11:55 AM

I have also noted that performance on NV is better in flat-field scopes, or those with minimal field curvature.


  • Gavster likes this

#3 bobhen

bobhen

    Cosmos

  • *****
  • Posts: 7,514
  • Joined: 25 Jun 2005

Posted 01 February 2023 - 01:16 PM

I agree.

 

The smaller field gave me pause as well but I soon discovered that I would rather have a smaller field with the Horsehead Nebula in it rather than a larger field without the nebula. And that smaller field is so rich that you suddenly have no regrets that you sold off those ultra-widefield eyepieces to get an intensifier!

 

The brighter stars are not pinpoint like in glass. Then again, that smudge in glass resolves into a globular with NV. I'll take door number two.

 

NV isn't perfect (what is) but then again neither is glass. The big problem with glass is that you don't see as much. And I find that problem to be a much bigger problem than any of the ones using NV.

 

Bob


  • RamStrocsop and D-zen like this

#4 WheezyGod

WheezyGod

    Apollo

  • -----
  • Posts: 1,346
  • Joined: 07 Jun 2021
  • Loc: Massachusetts, USA

Posted 01 February 2023 - 01:25 PM

Before purchasing, I had two major concerns about purchasing an NVD
1. Would I mind a small FOV of 40 degrees?
2. Will the aesthetics of the star display bother me?

I found it challenging to clear both of these doubts just by reading online forums. An evening with NVD under the stars would solve my worries, but no one in my immediate or distant surroundings has such a device.
In the end, encouraged by the posts on this forum, I decided to buy 'blindly', the price is ridiculous :-), but it turned out to be my best investment in this hobby of ours!

So, for those who may be in a similar situation:

1. Small FOV?

I really enjoy the relatively large FOV of my Morpheus, Pentax, and even Panoptic eyepieces. I was truly afraid that those 40 degrees would be too little for me. What can I say, never but never does the view through the NVD seem cramped to me. I can't explain why, probably a combination of the amount of information in those 40 degrees and the long eye relief. Simply, for me personally, those 40 degrees are not a problem at all.
The NVD FOV has become so natural to me that recently I started using my Baader ortho eyepieces for DSO as well :-)

2. Aesthetics of the view compared to glass eyepiece?

Before buying, I saw on internet forums a lot of nice (processed) photos through NVD eyepieces, but also a lot of terribly bad photos and ugly green flashing videos :-) of NVDs in action. I wasn't sure what to expect.
When I inserted my new NVD (OVNI-M 2100) into the diagonal, at first glance, the aesthetics of the view were truly worse, but after a little use, I would even say that it is not so bad as different compared to glass.
So, first of all, NVD does not have the colors of the stars, but it also does not have the pinpoint brilliance and dynamics of the view through a quality glass eyepiece.
On the other hand, when in the 4-inch achromat, in bortle7, you see a resolved small M79 globular cluster at only 16 degrees ALT through the haze of the atmosphere, then the aesthetics somehow fade into the background. In my opinion, the best description of the image would be that the aesthetic is similar to those invented scientific photographic plates with black stars on a white background.
When I start observing the stars through the NVD, somehow I put myself in that beautiful-ugly 'scientific' mode where what you see is more important, not whether the object you see sparkles beautifully :-). And what is most important in my opinion, I really enjoy that presentation, even though it is somewhat worse. When I'm hungry for beauty, I put in Pan35 and turn to Pleiades or DoubleCluster.
One more thing to add, the overall image quality is much better in prime focus compared to afocal, it is also slightly better in the APO telescope than in achromat, so that should be kept in mind. All of this refers primarily to the aesthetics of the star display, the nebulae are phenomenal through NVD.

Of course YMMV.

Clear skies to all!


I had these same two concerns as well but didn’t see any complaints about the smaller FOV from those who made the leap, and the better looking images showed stars that looked good enough for me. If stars were overly impacted then it would be hard to hide this even with a dedicated camera and heavy post processing.

I think it’s the long eye relief but also that the size of the eyepiece is quite big. Some of those orthos it’s like looking through a straw and if your head isn’t positioned well you’re not able to take in the full, yet small FOV.

I also noticed that the quality of the stars isn’t the same but it’s an easy compromise to make when I’m seeing so much more with NV. Depending on how much you turn the gain up (I like it fairly high) it doesn’t feel as much like you’re looking at a night sky because the sky background isn’t as dark and again because of the stars being a bit bloated as well as the halo on brighter stars.

For me these downsides don’t bother me as much because I’m seeing stuff I wouldn’t be able to see otherwise. It’s also seeing a better version of most objects as well. A globular cluster like M79 in my bortle 5/6 skies wouldn’t be interesting for me with glass alone, but with NV this mag 7.7 GC is about as interesting as M13/M5/M22 in bortle 4 skies with glass alone.

I think it really depends what’s important to an observer. Most of us would love to see color in objects but 98-99% of objects aren’t going to show color, and even if they do it’s subtle unless you have a very large scope under dark skies and even then it’s only certain objects.
There’s some using NV at very low gain and using averted vision because they prefer a dark sky background and believe they still see more with averted vision (they don’t and averted vision isn’t as sharp as direct).

One thing I’m interested in is your point on prime vs. afocal. I got a Mod3 before they became discontinued because I wanted the ergonomics of prime when possible and the better view that some have noticed with prime vs. afocal even though this has been debated more. What setups are you using for each where you’ve seen a better view in prime?
  • GeezerGazer and D-zen like this

#5 bbasiaga

bbasiaga

    Soyuz

  • *****
  • Posts: 3,655
  • Joined: 10 May 2006

Posted 01 February 2023 - 03:53 PM

There is still something to be said for straight up glass viewing.  But NVD is just like another eyepiece.  You are selecting it for its characteristics  - i.e. to be able to see things in a way that is not possible with a glass eyepiece.  So you put up with the downsides.  Every eyepiece has its downsides too.  

 

 

 

I only have afocal mode, so can't comment on the differences there.  


  • D-zen likes this

#6 D-zen

D-zen

    Lift Off

  • -----
  • topic starter
  • Posts: 8
  • Joined: 27 Oct 2022
  • Loc: SouthEast Europe

Posted 01 February 2023 - 04:06 PM

One thing I’m interested in is your point on prime vs. afocal. I got a Mod3 before they became discontinued because I wanted the ergonomics of prime when possible and the better view that some have noticed with prime vs. afocal even though this has been debated more. What setups are you using for each where you’ve seen a better view in prime?


I use 4inch f5 achromat and 12inch F5 dob with OVNI-M NVD. Before I got the TV67mm plossl I used the Panoptic35, TV32 plossl and budget celestron 40mm plossl for afocal.
The Celeston eyepiece had all possible aberrations, the TV32 was slightly better. Both had significant vignetting. The Pan35 was better corrected but with the OVNI afocal adapter it had significant vignetting. I even designed and 3d printed my own adapter for it. Since I bought the TV67, I have been using it exclusively for afocal access.
The OVNI afocal adapter is not bad, but it is not exactly the happiest solution either, so the vignetting may partly come from it, i.e. from the imperfect position of the nvd lens. The good thing is that the OVNI adapter can be screwed onto the TV67, so the system is solid. In TV67 there is a bit of vignetting and some coma, primarily because I don't have paracor. On the other hand NVD works with F2 so the nebulas are magnificent.
OVNI-M in prime mode is really good, no vignetting and nice stars to the edge, but with the system running at F5, there's not enough light for H-alpha filtering except for the brightest nebulae (m42). I use it for globs (even with barlows x2 and x3) and galaxies.

#7 D-zen

D-zen

    Lift Off

  • -----
  • topic starter
  • Posts: 8
  • Joined: 27 Oct 2022
  • Loc: SouthEast Europe

Posted 01 February 2023 - 04:17 PM

I agree.
 
The smaller field gave me pause as well but I soon discovered that I would rather have a smaller field with the Horsehead Nebula in it rather than a larger field without the nebula. And that smaller field is so rich that you suddenly have no regrets that you sold off those ultra-widefield eyepieces to get an intensifier!
 
The brighter stars are not pinpoint like in glass. Then again, that smudge in glass resolves into a globular with NV. I'll take door number two.
 
NV isn't perfect (what is) but then again neither is glass. The big problem with glass is that you don't see as much. And I find that problem to be a much bigger problem than any of the ones using NV.
 
Bob


I agree 100%

#8 Gavster

Gavster

    Apollo

  • *****
  • Posts: 1,450
  • Joined: 07 Mar 2014

Posted 01 February 2023 - 06:36 PM

For observing emission nebulae with an ha filter I aim to get to an effective f2 or lower which generally means using the afocal approach for most scopes, apart from very fast prime camera lenses. For afocal I think the quality of the front lens is critical to get sharpest views and imo the Carson milspec lens for the pvs-14 is the best for this.

 

With a Carson front lens I’ve found the 67mm gives good sharpness in afocal mode with my 16 inch f4 dob and 130mm f6.3 refractor. I also use my pvs14 in prime mode and in this setup the edge stars are a bit better corrected but with an ha filter the live nebulae views are less bright and less detailed.

 

Regarding nv pics, the vast majority posted on cn aren’t post processed.


Edited by Gavster, 01 February 2023 - 10:12 PM.


#9 HouseBuilder328

HouseBuilder328

    Viking 1

  • -----
  • Posts: 638
  • Joined: 24 Apr 2019
  • Loc: Raleigh, NC / USA

Posted 01 February 2023 - 11:15 PM

I had these same two concerns as well but didn’t see any complaints about the smaller FOV from those who made the leap, and the better looking images showed stars that looked good enough for me. If stars were overly impacted then it would be hard to hide this even with a dedicated camera and heavy post processing.

I think it’s the long eye relief but also that the size of the eyepiece is quite big. Some of those orthos it’s like looking through a straw and if your head isn’t positioned well you’re not able to take in the full, yet small FOV.

I also noticed that the quality of the stars isn’t the same but it’s an easy compromise to make when I’m seeing so much more with NV. Depending on how much you turn the gain up (I like it fairly high) it doesn’t feel as much like you’re looking at a night sky because the sky background isn’t as dark and again because of the stars being a bit bloated as well as the halo on brighter stars.

For me these downsides don’t bother me as much because I’m seeing stuff I wouldn’t be able to see otherwise. It’s also seeing a better version of most objects as well. A globular cluster like M79 in my bortle 5/6 skies wouldn’t be interesting for me with glass alone, but with NV this mag 7.7 GC is about as interesting as M13/M5/M22 in bortle 4 skies with glass alone.

I think it really depends what’s important to an observer. Most of us would love to see color in objects but 98-99% of objects aren’t going to show color, and even if they do it’s subtle unless you have a very large scope under dark skies and even then it’s only certain objects.
There’s some using NV at very low gain and using averted vision because they prefer a dark sky background and believe they still see more with averted vision (they don’t and averted vision isn’t as sharp as direct).

One thing I’m interested in is your point on prime vs. afocal. I got a Mod3 before they became discontinued because I wanted the ergonomics of prime when possible and the better view that some have noticed with prime vs. afocal even though this has been debated more. What setups are you using for each where you’ve seen a better view in prime?

 

What kind of lens on the scope would help with this issue?  A doublet?  Triplet?  ED glass?  Higher grades like FPL-53 or Lanthanum coatings?  Or it’s all minimal improvements like the last 5% improvement?



#10 bobhen

bobhen

    Cosmos

  • *****
  • Posts: 7,514
  • Joined: 25 Jun 2005

Posted 02 February 2023 - 07:20 AM

I also noticed that the quality of the stars isn’t the same but it’s an easy compromise to make when I’m seeing so much more with NV. Depending on how much you turn the gain up (I like it fairly high) it doesn’t feel as much like you’re looking at a night sky because the sky background isn’t as dark and again because of the stars being a bit bloated as well as the halo on brighter stars.

 

What kind of lens on the scope would help with this issue?  A doublet?  Triplet?  ED glass?  Higher grades like FPL-53 or Lanthanum coatings?  Or it’s all minimal improvements like the last 5% improvement?

The scopes I use are a 102mm F5 achromatic refractor, a 102mm F7.5 apochromatic triplet refractor and an 8" F10 SCT. The all can be used reduced. I observe in prime mode.

 

I find that bright stars are more degraded in all the scopes. But, for example, globulars show very pinpoint-like stars in all the scopes as well. So, it's the brightness of the point-source that seems to matter most not the optics.

 

The intensifier itself is the main cause of degradation not so much the optics. Now, better data in better data out of course. But I find any differences in the scopes above to be somewhat minimal and the real cause of bright star degradation is the intensifier. Filters will also add to that as well. And there really aren't any bright stars that I want to look at with an intensifier anyway.

 

Like other intensifier aberrations, I find they are all rather easily ignored when one is studying the main object of interest. When that smudge resolves into a globular with pinpoint stars or when you see M35 and 2158 fill the field and 2158 is bright and resolved into pinpoints all is soon forgotten and forgiven.

 

Bob


  • blackhaz, Dale Eason and chemisted like this

#11 WheezyGod

WheezyGod

    Apollo

  • -----
  • Posts: 1,346
  • Joined: 07 Jun 2021
  • Loc: Massachusetts, USA

Posted 02 February 2023 - 12:41 PM

I also noticed that the quality of the stars isn’t the same but it’s an easy compromise to make when I’m seeing so much more with NV. Depending on how much you turn the gain up (I like it fairly high) it doesn’t feel as much like you’re looking at a night sky because the sky background isn’t as dark and again because of the stars being a bit bloated as well as the halo on brighter stars.

The scopes I use are a 102mm F5 achromatic refractor, a 102mm F7.5 apochromatic triplet refractor and an 8" F10 SCT. The all can be used reduced. I observe in prime mode.

I find that bright stars are more degraded in all the scopes. But, for example, globulars show very pinpoint-like stars in all the scopes as well. So, it's the brightness of the point-source that seems to matter most not the optics.

The intensifier itself is the main cause of degradation not so much the optics. Now, better data in better data out of course. But I find any differences in the scopes above to be somewhat minimal and the real cause of bright star degradation is the intensifier. Filters will also add to that as well. And there really aren't any bright stars that I want to look at with an intensifier anyway.

Like other intensifier aberrations, I find they are all rather easily ignored when one is studying the main object of interest. When that smudge resolves into a globular with pinpoint stars or when you see M35 and 2158 fill the field and 2158 is bright and resolved into pinpoints all is soon forgotten and forgiven.

Bob


Yup I completely agree on globulars and in general, smaller stars looking fine in NV where there’s far less bloating. Conversely, an open cluster can be less ideal since they typically have brighter stars and sometimes blue stars which NV is less effective on.

#12 slavicek

slavicek

    Viking 1

  • *****
  • Posts: 994
  • Joined: 01 Aug 2017
  • Loc: Massachusetts

Posted 02 February 2023 - 01:01 PM

I am glad D-zen made a fair assessment of the pros/cons of NV.

 

As I posted elsewhere, one should not be getting the NV to look at color stars (like doubles) or planets. NV is good for "deep sky".

And, even thou I use Ethos (100 deg FOV) for observing, the "narrow" FOV of NV does not bother me a bit. I thing the trick is to use correct FOV for the given object and as long as the object you are looking at fits the FOV you are good.

 

My 2c.


  • Joko and jconroy like this

#13 bobhen

bobhen

    Cosmos

  • *****
  • Posts: 7,514
  • Joined: 25 Jun 2005

Posted 02 February 2023 - 03:29 PM

Yup I completely agree on globulars and in general, smaller stars looking fine in NV where there’s far less bloating. Conversely, an open cluster can be less ideal since they typically have brighter stars and sometimes blue stars which NV is less effective on.

Yes. But there are also usually stars in open and globular clusters that are too dim to be seen with glass but are easily seen with NV. 

 

Bob



#14 D-zen

D-zen

    Lift Off

  • -----
  • topic starter
  • Posts: 8
  • Joined: 27 Oct 2022
  • Loc: SouthEast Europe

Posted 02 February 2023 - 04:07 PM

I think there are quite a few open clusters that benefit from NV like M37 or M46, especially in smaller telescopes.
  • bobhen likes this

#15 Joko

Joko

    Vendor - OVNI

  • *****
  • Vendors
  • Posts: 831
  • Joined: 21 May 2008
  • Loc: France, Europe

Posted 22 July 2023 - 04:32 AM

I think there are quite a few open clusters that benefit from NV like M37 or M46, especially in smaller telescopes.

Most open clusters are very large. To see them in their totality they require afocal observation with long focal length eyepieces (such as the TV67mm) or a small telescope with a short focal ratio. Using a small telescope in prime will give sharper stars than in afocal.
So there's no need for a big telescope and some are also better to observe with your OVNI-M hand-held at x1 or higher magnification, such as x3 or x5.
Of course, no filter is necessary. But for someone observing in a light-polluted area, an IR Pass 685nm is recommended to darken the sky and to provide more contrast.

Edited by Joko, 22 July 2023 - 06:05 AM.

  • Speedy1985 likes this

#16 Frank2

Frank2

    Mariner 2

  • *****
  • Posts: 298
  • Joined: 26 Mar 2009
  • Loc: SC

Posted 22 July 2023 - 07:20 AM

My 2¢. NV is another tool. I have eyepiece view, UHC and OIII filter views, and NV. I will pick a target and examine it with each option. I am mainly looking at DSO's in a sky where the Milky way is ever so faint, if visible at all, with an 11" Cat. Typically the eyepiece view is usually the least impressive. The filters bring out significant details, and the NV multiplies the effect. However, the progression does not always follow that path, which makes each observation so interesting. Some examples, I did a goto on the Cresent Nebula. My gotos are usually very accurate, but nothing showed in the eyepiece. I viewed through the filters and again nothing. I put the NV in and there was the Cresent faintly, but clearly, visible. The M51 eyepiece view showed a concentrated center with a diffuse outer area and the companion. The filtered views made the galaxy disappear, and the NV view was no better than the eyepiece view but added the NV artifacts such as scintillation and star bloating. Swan nebula was faintly visible in the eyepiece, showed a lot more contrast with the filters and exploded with nebulosity with NV. There was some remnant of nebulosity in almost the entire view. M57 ghostly but plainly visible in eyepiece, darker with more contrast in the filterd view, and in your face in NV with the hinted at central haze in the filterd view there to see by even inexperienced observers. NGC 6139, this faint globular was a pale, almost not there, unresolved smudge in the eyepiece. The filters made it dissapear. NV resolved about a dozen stars. The Helix Nebula was invisible in the eyepiece and with filters. It showed as a very faint, but distinct doughnut in NV. After seeing it in NV I could tell something was there with the UHC filter, but could not make out the shape. One of the planetaries, I forget which one Saturn Nebula maybe, showed well in the eyepiece, better with more contrast with the filters, and was noticebly less distinct in NV. Special note: the NV views are usually made using a 6nm IR filter, but not always, and a 6.3 focal reducer is also part of the mix. Using NV for me just adds another dimension to the viewing experience. Not to mention that using the NV alone I can see, at zero magnification, stars that are usually only visible in 10x50 binoculars. That never gets old. The whole zero power NV use is beyond the scope of this post, but let me say that it opens up a whole new observation experience with nebulas, meteors, and satelites. One last note, if observing at night in a dark location, and a strange noise is heard in the middle of the night with a pile of expensive equipment all around you, is it a fox, snake, bear, person? Putting the NV to your eye turns night into day. Could I live without NV now? It would be difficult.

Edited by Frank2, 22 July 2023 - 04:55 PM.

  • slavicek likes this


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