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Filters to better preserve dark adaptation when using night vision devices?

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#1 ABQJeff

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Posted 28 July 2022 - 02:30 PM

I plan to purchase a PVS-14 NV device for my SCTs and Fracs.  I very much enjoy visual observing and just want to enhance the views without distracting from the wonder and awe of observing from a dark site.

 

The one concern I have with NV at a dark site (Bortle 1-2, SQM > 21.5) is the NV device ruining dark adapted viewing of the Milky Way naked eye or in viewing faint galaxies or faint open star clusters thru glass (I read these don’t benefit as greatly from NV at dark sites).  I have read that others turn their gain way low when at dark sites and that the NV device is no more obtrusive to dark adapted vision than SS is in night mode on an iphone (is this true?)

 

Regardless, if it is of any benefit, I was thinking would an Amber filter at the ocular objective (eye end) used with a White Phosphor device help?

 

https://tnvc.com/sho...sentinel-dtnvg/

 

I know these are designed to blend with green NV, but I was thinking they could help with retaining dark adaption when using white phosphor tubes.  Thoughts?

 

(btw on web sites, looks like the occular thread is 30mm so different from 1.25” EP filter thread, darn…please correct if that is not true as I could then just use a red 1.25” filter)

 

Thanks for any insight/responses!

 

Jeff

 

 



#2 sixela

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Posted 28 July 2022 - 03:08 PM

An amber filter would mean you’d only see details bright enough to be seen with photopic vision, and that might help with EEA…but frankly with a night vision device I have to look with averted vision (i.e. scotopic vision) for the faintest details, so that would be rather counterproductive.

Edited by sixela, 28 July 2022 - 03:10 PM.


#3 JMW

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Posted 28 July 2022 - 03:51 PM

I use my left eye for normal astronomy and use my right eye with the PVS14.


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#4 ABQJeff

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Posted 28 July 2022 - 03:53 PM

An amber filter would mean you’d only see details bright enough to be seen with photopic vision, and that might help with EEA…but frankly with a night vision device I have to look with averted vision (i.e. scotopic vision) for the faintest details, so that would be rather counterproductive.

Wow, so you still have to use averted vision with NV devices?  I thought all the ‘rage’ on these was you could direct viewing of even the faint visual objects?  So great for outreach, no averted vision needed.



#5 ABQJeff

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Posted 28 July 2022 - 03:54 PM

I use my left eye for normal astronomy and use my right eye with the PVS14.

I have read others do this as well.  Thing is I am very much right eye dominant.



#6 sixela

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Posted 28 July 2022 - 03:59 PM

Wow, so you still have to use averted vision with NV devices? I thought all the ‘rage’ on these was you could direct viewing of even the faint visual objects? So great for outreach, no averted vision needed.

Depends what you mean.

It makes some barely visible objects without NV look as if they were M42 in a big scope, but there’s still even fainter stuff that with NV is hardish to see rather than completely invisible when using glass eyepieces.

Also there is stuff for which it barely helps. M33 at a dark site at low power is still better with good glass than with an NVD (except for some of the open clusters in it).

You’re making it sound as if you were looking at a bright TV screen, and that’s not how it looks. Apart from the scintillation when the gain’s too high it feels very much like an eyepiece.

Edited by sixela, 28 July 2022 - 04:06 PM.

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#7 RodShea

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Posted 28 July 2022 - 06:57 PM

I’m using NV at Bortle 1-3 sites, as well as observing with glass alone. I’m finding that, yes, the NV takes the edge off my night vision, but the effect is temporary. It is much less of a problem than looking at Jupiter. I usually have the gain so scintillations are just barely visible. Some people set theirs a bit higher than I usually do. The thrill of seeing so much more of the h alpha is worth any temporary loss of night vision

So far as averted vision, I can see detail far better by turning up the gain than trying averted vision with the monocular.
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#8 ABQJeff

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Posted 28 July 2022 - 07:57 PM

Thank you, all these replies are very informative for someone who has never looked thru a NV device.


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#9 ABQJeff

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Posted 28 July 2022 - 08:00 PM

I’m using NV at Bortle 1-3 sites, as well as observing with glass alone. I’m finding that, yes, the NV takes the edge off my night vision, but the effect is temporary. It is much less of a problem than looking at Jupiter. I usually have the gain so scintillations are just barely visible. Some people set theirs a bit higher than I usually do. The thrill of seeing so much more of the h alpha is worth any temporary loss of night vision

So far as averted vision, I can see detail far better by turning up the gain than trying averted vision with the monocular.

Ok much less than Jupiter, that is a helpful benchmark, how about versus looking at Sky Safari in night mode, or your red beam flashlight reflecting off the ground, or an illuminated hand controller?  I am just trying to get an idea of what to expect.

 

Thanks!



#10 bobhen

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Posted 29 July 2022 - 06:14 AM

Don’t worry about dark adaption. Get the intensifier. You will be blown away. It’s kind of a new way of observing so you have to toss out some old notions. The intensifier "light" is just not that strong.

 

If you want to look at the Milky Way, many NV users use camera lenses or 50mm guide scopes, etc. to get extremely wide field, low power NV views that will show you the Milky Way, literally, in a whole new light. The Milky Way is more impressive with NV than naked eye. With NV you will gain a whole new perspective and respect for our galaxy.

 

You could always start your session with glass and then move to NV. But to be honest there is no real need to do so and every time I put a glass eyepiece in the scope it is pulled out rather quickly.

 

Galaxies and clusters are all enhanced but just like with visual some are better seen than others. You will be able to resolve clusters that were previously difficult to resolve or just smudges. Many galaxies will become easier to spot. Cygnus will become filled with nebulas and Sagittarius will become so thick with stars that dark nebulas will be easy to see against the background glow. Some objects that were previously thought to be imaging targets will become observable.

 

Averted vision is still used because the universe is a rather large place and although NV makes many objects easier to see and with added details there are still new, faint objects that are the limit, just as there are still objects at the limit with the Hubble telescope.

 

The two filters that you need are a Pass filter (610 for mild light pollution and a 685 for heavy light pollution), for non-nebula objects, and a Ha filter (many start with a 6 or 7 nm Ha filter) for nebulas. Forget visual filters of any kind.

 

With NV, the wonder of the Milky Way is not diminished as a matter of fact it is “greatly enhanced”. 

 

Your SCT for small stuff and your refractors for low power, wide field views are perfect. An SCT and refractors (achromatic refractors work well) are also what I use. If you don’t have one, a reducer for the SCT will come in handy. One look through a small, fast refractor with NV and you will probably want to go even wider, hence why many add camera lenses.

 

One session and you’ll figure out the minor adjustments you need to make or the added accessories you might want to add.

 

My intensifier is the best accessory I purchased in over 40-years of observing.

 

Have fun exploring a "new" Milky Way.

 

Bob


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#11 ABQJeff

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Posted 29 July 2022 - 09:36 AM

Don’t worry about dark adaption. Get the intensifier. You will be blown away. It’s kind of a new way of observing so you have to toss out some old notions. The intensifier "light" is just not that strong.

 

If you want to look at the Milky Way, many NV users use camera lenses or 50mm guide scopes, etc. to get extremely wide field, low power NV views that will show you the Milky Way, literally, in a whole new light. The Milky Way is more impressive with NV than naked eye. With NV you will gain a whole new perspective and respect for our galaxy.

 

You could always start your session with glass and then move to NV. But to be honest there is no real need to do so and every time I put a glass eyepiece in the scope it is pulled out rather quickly.

 

Galaxies and clusters are all enhanced but just like with visual some are better seen than others. You will be able to resolve clusters that were previously difficult to resolve or just smudges. Many galaxies will become easier to spot. Cygnus will become filled with nebulas and Sagittarius will become so thick with stars that dark nebulas will be easy to see against the background glow. Some objects that were previously thought to be imaging targets will become observable.

 

Averted vision is still used because the universe is a rather large place and although NV makes many objects easier to see and with added details there are still new, faint objects that are the limit, just as there are still objects at the limit with the Hubble telescope.

 

The two filters that you need are a Pass filter (610 for mild light pollution and a 685 for heavy light pollution), for non-nebula objects, and a Ha filter (many start with a 6 or 7 nm Ha filter) for nebulas. Forget visual filters of any kind.

 

With NV, the wonder of the Milky Way is not diminished as a matter of fact it is “greatly enhanced”. 

 

Your SCT for small stuff and your refractors for low power, wide field views are perfect. An SCT and refractors (achromatic refractors work well) are also what I use. If you don’t have one, a reducer for the SCT will come in handy. One look through a small, fast refractor with NV and you will probably want to go even wider, hence why many add camera lenses.

 

One session and you’ll figure out the minor adjustments you need to make or the added accessories you might want to add.

 

My intensifier is the best accessory I purchased in over 40-years of observing.

 

Have fun exploring a "new" Milky Way.

 

Bob

Thank you Bob!  Very nice rundown and summary of NV astronomy.  Yes I still do plan to get an NV device and the dedicated filters for it.  And you are correct, my multiple scopes (plus a C11 and 0.7 reducer and some 3x and 5x afocal lenses for handheld use) will give me a large range of views from 40 degrees down to 1.2 degrees all faster than F/4.

 

CS!



#12 RodShea

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Posted 29 July 2022 - 01:23 PM

Ok much less than Jupiter, that is a helpful benchmark, how about versus looking at Sky Safari in night mode, or your red beam flashlight reflecting off the ground, or an illuminated hand controller? I am just trying to get an idea of what to expect.

Thanks!



#13 RodShea

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Posted 29 July 2022 - 01:31 PM

I use different equipment, so I can’t answer directly. Having said that, the loss is mild, temporary, and tolerable to me. I’m also older, and use dark ground cloths and an eyepatch. If I’m looking at something faint, I’ll use a hood, so I’m careful about dark adaptation. I think it is mainly pupil construction and not the longer term biochemical changes in the retina, but that is ia guess. It is well worth it.
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#14 ABQJeff

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Posted 29 July 2022 - 01:50 PM

I use different equipment, so I can’t answer directly. Having said that, the loss is mild, temporary, and tolerable to me. I’m also older, and use dark ground cloths and an eyepatch. If I’m looking at something faint, I’ll use a hood, so I’m careful about dark adaptation. I think it is mainly pupil construction and not the longer term biochemical changes in the retina, but that is ia guess. It is well worth it.


Thanks Rod!!

#15 Deadlake

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Posted 30 July 2022 - 01:17 PM

plus a C11 and 0.7 reducer

Which reducer?
You might need to get the AP Tele compressor as it has 150 mm of back focus which you will need when using the NVD focally.



#16 Jeff Morgan

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Posted 30 July 2022 - 02:14 PM

I started out using both regular and NV with the intensity turned down.

 

Then I realized any faint fuzzy that requires averted vision is going to be better in NV.

 

Go ahead and buy the intensifier and turn it down, or save it for the end of the session. But I predict you won’t be splitting time for very long. 


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#17 sixela

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Posted 30 July 2022 - 03:17 PM

That depends on where you are observing.

Except for edge-ons and the rare galaxy in the zone of avoidance I find that in good Bortle class 4 skies and darker a lot of galaxies look better through glass than through an NVD.

Edited by sixela, 30 July 2022 - 03:21 PM.

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#18 ABQJeff

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Posted 30 July 2022 - 05:01 PM

Which reducer?
You might need to get the AP Tele compressor as it has 150 mm of back focus which you will need when using the NVD focally.

The Edge 0.7 reducer which maintains its 146mm backfocus (and I plan to do afocal with the Televue adapter, put my 'glass' to some use wink.gif )



#19 ABQJeff

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Posted 30 July 2022 - 05:11 PM

Thanks all for the replies/insight, keep them coming. 

 

I haven't seen any direct comparisons yet of effect on dark adaptation due to intensifier light (other than 'less than Jupiter').    Same as SS in night mode (in which case great, I use that all the time), or an  illuminated hand controller (even better), or bright as the red light on a flashlight reflecting off the ground/equipment as you hunt for gear (ok, I don't do that much, it ruins vision a little but it quickly recovers, so acceptable), or same as Saturn (ok better than Jupiter, but not great, kind of like the red flashlight off the ground),  same as a double star, like Albireo or Castor (awesome, barely any effect there), like a car's headlights passing by next to you (egads, no! I know that is more than Jupiter, so no it isn't that wink.gif), you get the idea.

 

Thanks Again!

 

CS!

 

Jeff



#20 Jeff Morgan

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Posted 31 July 2022 - 10:57 AM

I know, it’s hard to let go of the Old Ways.

 

If this really bugs you, just leave the intensifier in the case until the last hour of your session. It’s your session to manage. 

 

But trust me, you’ll get used to direct vision. 
 

All of the dorky stuff I did in the years before NV - carrots, red goggles, yes once I even pulled the portable oxygen bottle out of my glider - never again.


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#21 ABQJeff

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Posted 01 August 2022 - 03:16 AM

I know, it’s hard to let go of the Old Ways.

 

If this really bugs you, just leave the intensifier in the case until the last hour of your session. It’s your session to manage. 

 

But trust me, you’ll get used to direct vision. 
 

All of the dorky stuff I did in the years before NV - carrots, red goggles, yes once I even pulled the portable oxygen bottle out of my glider - never again.

"once I even pulled the portable oxygen bottle out of my glider"...don't tell me you flew into a dark site with your telescopes and glider, now THAT would really be trying to get away from LP lol.gif

 

(I assume you pulled it from your glider and brought it with you in a road vehicle wink.gif )




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