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Need some advice on NV

NV
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#1 nicknacknock

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Posted 04 September 2018 - 01:33 AM

Jeff's last thread was the tipping point for me!

 

I may soon have some spare funds which I would like to spend invest on a NV solution. I am inspired by what one can do with these devices and it is something I want to look into seriously. Being based in Europe restricts what kind of equipment I can get, so I guess I am "stuck" on tubes from Photonis. I am not so concerned by the tube specs for the moment, but I would like to learn (and start planning) on how to construct a NV kit.

 

There are two ways to go about this, hand-holding and through a scope and I am interested in both solutions. The question is simple: Specifically what do I need (would prefer white phosphor image) to make it work in terms of:

 

1. Filters

2. Eyepieces for afocal and / or reducers (I have the classic 1.25" 0.5x reducer and there are 2" 0.5x reducers)

3. Accessories to make the tube usable and able to connect to scope / eyepieces

4. Anything else that would be nice to have / would enhance the experience

 

Let's forget about the actual tube for a minute. While it being the most expensive part of such a kit, discussing tube specifications is a whole different subject by itself. I just want to understand what a complete kit would entail and why.

 

Keep it simple please! I am a visual amateur astronomer who recently started EAA and keen to expand my horizons, but when it comes to NV I am a dunce, so yeah, short, sweet and simple! Thanks!

 

 


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#2 alanjgreen

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Posted 04 September 2018 - 02:37 AM

FILTERS

If you want to keep it simple, then get a PVS-14 from actinblack (Luxembourg). The PVS-14 will work hand-held straight off as it has an objective lens already. The PVS-14 also has a manual "gain" control that is more than useful to tune the view to the conditions and eek out the arms of galaxies for example. The lower you can live with the gain then the higher the signal noise ratio so there is a juggling act to be played.

 

I use a 1.25" Astronomik 12nm Ha CCD filter for x1 hand-held nebula viewing and a 1.25" Castell UHC for hand held Milky Way viewing. The filters can simply be inserted inside the protective objective cover (Sacrificial Window) for no cost solution as it comes with the NVsmile.gif

filter-small.jpg

 

Or there is a 3D printed attachment that can be printed that moshen posted on CN - I use this 3D printed attachment.

x1filter.jpg

 

For scope use, you really need an Astronomik 6nm Ha CCD filter (or 7nm Baader Ha for lower cost) the narrower band brings greater contrast and much more nebulosity into the view. I also use a 2" 12nm Astronomik Ha CCD filter with smaller aperture scopes or at greater magnifications which lets more light into the objective and find that this can yield positive improvements to the views on some objects.

 

If you live with light pollution you will need a 610nm, 640nm or 670nm red filter to remove the light pollution otherwise the NVD will just amplify that too!

I use a Baader 610nm red filter when the big moon is out but otherwise I go filterless as I live in the mountains.

 

 

ACCESSORIES

If you have Televue eyepieces then the simplest solution is to buy the TNVC adapter from USA (no export restrictions on these) and it attaches to both PVS-14 and Televue Dioptrx.

Buy the TNVC adapter from TNVC directly. You have to email them to setup an order as their website only accepts orders from US addresses.

- They are easy to deal with and will create an invoice that you have to pay for via bank transfer. Shipping takes a couple of weeks to arrive and you may get customs charges.

See    https://stargazerslo...ronomy-adapter/

Also    https://tnvc.com/sho...ronomy-adapter/

tnvc-small.jpg

p35.jpg

 

 

EYEPIECES

You will need a TeleVue 55mm Plossl as it acts as x0.5 reducer to double your focal ratio, more light into the NVD is the goal, and provide huge exit pupil.

I also use Panoptic 35mm (which gives a much better image than the 55mm plossl) and also acts as a x0.7 reducer.

Then I use 27mm Panoptic and 18.2 Delite occasionally. As long as they have Dioptrx and around 20mm eye relief then they are ok. Below 18.2mm I find the view in the eyepiece to be too dim so that's as low as I go.

nveye.jpg

 

 

ANYTHING ELSE

Not really, with the PVS-14 its pretty straight forward smile.gif.

 

I wrote an afocal article that explains how the focal ratio changes work and has more info too...

https://stargazerslo...comment-3434224

 

HTH,

Alan


Edited by alanjgreen, 04 September 2018 - 03:23 AM.

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#3 nicknacknock

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Posted 04 September 2018 - 02:46 AM

Thanks Alan!

 

Very straight forward explanation and will allow me to quantify costs of all related accessories. My sincere thanks!

 

The PVS-14 provides a greenish image, correct? Any other options in white phosphorous besides Photonis which I know has these?

 

Re adapter, there is a shop close to my home which prints 3D parts :)


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#4 nicknacknock

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Posted 04 September 2018 - 02:47 AM

What's the price on the PVS-14? If you'd prefer not to say in public, just PM me. If you'd rather not disclose in general, no problem ;)



#5 alanjgreen

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Posted 04 September 2018 - 03:04 AM


The PVS-14 provides a greenish image, correct? Any other options in white phosphorous besides Photonis which I know has these?

 

Re adapter, there is a shop close to my home which prints 3D parts smile.gif

I am unsure of your question re: the greenish image?

The image colour is determined by your choics of tube. I am using White Phosphur and I feel it presents a view that is the most "familiar" to what I am used to seeing in my scopes. Of course all the stars lose their colours - that seems that only downside.

 

As to other options, you are best contacting actinblack and asking them what they recommend?

- be sure to specify that you want it for "astronomy" purposes smile.gif

- be sure to specify that you want really low "EBI < 0.8"

 

Reimer at actinblack knows his stuff and will be able to advise... He may or may not have what you want in stock and you may need to wait (I had to wait for 2 months but that was okay as i did not have the funds when I started looking smile.gif )


Edited by alanjgreen, 04 September 2018 - 03:10 AM.


#6 alanjgreen

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Posted 04 September 2018 - 03:05 AM

What's the price on the PVS-14? If you'd prefer not to say in public, just PM me. If you'd rather not disclose in general, no problem wink.gif

I paid 7000 euro for my PVS-14 with Photonis 4g INTENS tube.

If I remember correctly, the basic price for a PVS-14 was around 3200 euro then you add the cost of the specific tube that you pick, there are many tubes available from actinblack...

 

Photonis ECHO
Res: 57 lp/mm
SNR: 24
Sens: N/A
FOM: min 1500 – max 1800
Photonis Echo tubes with wide spectrum bandwidth. They see what others do not see.  Echo tubes allow for more spots, but at a great value and performance.

 

Photonis ECHO+
Res: 57 lp/mm
SNR: 26
Sens: N/A
FOM: min 1800
Photonis Echo+ tubes with wide spectrum bandwidth. They see what others do not see. Echo+ tubes allow for more spots, but at a great value and performance. Compared to regular Echo tubes these have a min FOM.

 

Photonis INTENS
Res: 64 lp/mm
SNR: 27 or 28
Sens: N/A
FOM: min 1800 or 2000
Wide spectrum image intensifier. Exceptionally high SNR and resolution. A much wider range of the light can be used with these tubes enabling them to beat Generation 3 in most environments.

 

See https://www.actinbla...ensifier-tubes/

 

They have tubes from "other" manufacturers but I dont know of anyone using them and its a risk "to be the first!"

 

Here is a pic of my delivery...

act.jpg


Edited by alanjgreen, 04 September 2018 - 03:24 AM.


#7 nicknacknock

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Posted 04 September 2018 - 03:35 AM

Thanks Alan, 

 

Yep, white phosphor is what I am interested as of course it simulates a more "natural" view.

 

I think you covered all bases and the sticker shock is quite a bit. Besides the cost of the tube and all, the cost of the narrow band filters, adapters and various odd bits need to be taken into consideration.

 

However, I know that it would be something that would give me great pleasure and it is something I need to plan for. Now that I have a good idea about what is needed, it's time to create a little EXCEL sheet and note everything down along with the costs involved.

 

Quick questions:

 

1. AFOV is 40°, correct? Meaning, I can restrict myself to eyepieces with close (or a bit larger AFOV and ignore vignetting) to this AFOV and be covered, yes?

 

2. Why would one choose the 55mm Plossl Vs the 40mm Plossl? I recall someone mentioning there is no limit on exit pupil but how does that work?

 

3. In relation to 2 above, could I use say a 32mm Plossl and a 0.5x reducer or some other reducer and stay at 55mm for example? It all ties to the first question. if AFOV is 40°, who cares about eyepieces with more AFOV? The point is to reduce magnification and thus increase TFOV.



#8 alanjgreen

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Posted 04 September 2018 - 03:51 AM

Thanks Alan, 


 

Quick questions:

 

1. AFOV is 40°, correct? Meaning, I can restrict myself to eyepieces with close (or a bit larger AFOV and ignore vignetting) to this AFOV and be covered, yes?

 

2. Why would one choose the 55mm Plossl Vs the 40mm Plossl? I recall someone mentioning there is no limit on exit pupil but how does that work?

 

3. In relation to 2 above, could I use say a 32mm Plossl and a 0.5x reducer or some other reducer and stay at 55mm for example? It all ties to the first question. if AFOV is 40°, who cares about eyepieces with more AFOV? The point is to reduce magnification and thus increase TFOV.

1. Yes 40 degree. Thats why I use Plossl & Panoptic mainly. If the eye relief does not match the distance to the objective then you can get dodgy edges so I picked 68 degree panoptic rather than 32 & 40 Plossl but they seem to work for everyone else.

 

2. you need to read my afocal article. The 55mm plossl acts as the largest focal ratio increaser and this means more light and brighter image. The NVDs work at f1.2 and we need to increase our scope speeds to match as best we can. The 55mm Plossl will double the speed of your scope. Second key point is that the NVD has a 20mm objective, we want to fill that objective with as large an exit pupil as possible. 55mm Plossl produces a 15mm exit pupil in my f3.6 dob...

 

https://stargazerslo...comment-3434224

 

3. Yes, people are using reducers. Watch for vignetting. I do not use them so I cannot answer this question. Someone else will chime in....  The point is to increase the focal ratio to match the NVD.


Edited by alanjgreen, 04 September 2018 - 03:57 AM.

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#9 outofsight

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Posted 04 September 2018 - 03:53 AM

"There are two ways to go about this, hand-holding and through a scope and I am interested in both solutions." Three ways, now that you put it that way.

 

Not in any meaningful order, although I would strongly recommend you try to have a system that will work at prime focus in various scopes. I'm not sure of all your options for where you are, but I'm pretty sure that Photonis is quite alright. 1. The device itself with the objective that it comes with, and with such things as camera lenses if they can be connected (not with a PVS-14, as far as most PVS-14s I've ever seen), that's handheld. 2. Afocally, like what is being shown in some of the above. 3. And the third way is with a C mount to 1.25" adapter directly into a telescope, in general, from what I know, that can't be done with a PVS-14.

 

Keep reading and researching. It seems complex to the uninitiated, just like many other things, but I can't say it's any more complex than any other telescope stuff. Just keep checking things out until you have your own good understanding. 


Edited by outofsight, 04 September 2018 - 03:54 AM.

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#10 nicknacknock

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Posted 04 September 2018 - 04:24 AM

Sigh, the reading never stops....


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#11 nicknacknock

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Posted 04 September 2018 - 04:25 AM

On it 

 

2. you need to read my afocal article. 

 

https://stargazerslo...comment-3434224

 

 



#12 TOMDEY

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Posted 04 September 2018 - 07:07 AM

Good discussion! I have a very small adapter that allows me to screw 1.25 filters directly over my 1x lens.  Tom



#13 Jeff Morgan

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Posted 04 September 2018 - 08:17 PM

Jeff's last thread was the tipping point for me!

 

I may soon have some spare funds which I would like to spend invest on a NV solution. I am inspired by what one can do with these devices and it is something I want to look into seriously. Being based in Europe restricts what kind of equipment I can get, so I guess I am "stuck" on tubes from Photonis. I am not so concerned by the tube specs for the moment, but I would like to learn (and start planning) on how to construct a NV kit.

 

There are two ways to go about this, hand-holding and through a scope and I am interested in both solutions. The question is simple: Specifically what do I need (would prefer white phosphor image) to make it work in terms of:

 

1. Filters

2. Eyepieces for afocal and / or reducers (I have the classic 1.25" 0.5x reducer and there are 2" 0.5x reducers)

3. Accessories to make the tube usable and able to connect to scope / eyepieces

4. Anything else that would be nice to have / would enhance the experience

 

Let's forget about the actual tube for a minute. While it being the most expensive part of such a kit, discussing tube specifications is a whole different subject by itself. I just want to understand what a complete kit would entail and why.

 

Keep it simple please! I am a visual amateur astronomer who recently started EAA and keen to expand my horizons, but when it comes to NV I am a dunce, so yeah, short, sweet and simple! Thanks!

 

Congratulations!

 

As far as the Photonis, from photos and posts by Alan Green and Gavster they appear to be excellent tubes. And if Photonis is the only game in town, comparisons to L3 are kind of a moot point, eh?

 

Presumably the PVS-14 is the only device (housing) you would have access to, so you would want the TNVC afocal adapter.

Another option to look at is the Baader Zoom option: https://www.cloudyni...t-vision-setup/

 

The Baader would of course only cover the higher power NV options. The zoom would be faster operationally than swapping out the TNVC adapter between eyepieces, which I find to be slow. Of course, you could get a TNVC adapter for each eyepiece, they are relatively inexpensive.

 

You will want at least one long pass filter and one h-alpha. Your choice of bandwidth and filter size. 640 long pass and 12nm H-alpha tend to be "safe" choices. And the least expensive.

 

If you want to do 1x viewing, go to RAF camera and get the ENVIS->1.25" astro filter adapter. Yes, the PVS-14 does not have the ENVIS lens, but the PVS lens and ENVIS lens have the same thread.

 

If you go PVS-14, look at getting the military snap-on 3x afocal lens. Serves the same role as an 85mm telephoto lens in the C-mount world.

 

And get Astrophotography Atlas by Bracken. You will have access to so many more emission nebula that your traditional visual atlases become extremely limiting.

 

That would be your basic kit, assuming an afocal-only device.


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#14 Jeff Morgan

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Posted 04 September 2018 - 08:19 PM

Yes, as the others have said, get a C-mount housing if possible. It is superior in terms of versatility and connectivity.

 

C-Mount can do afocal.

 

Afocal can not do everything C-mount can.




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