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

Small aperture + NV vs. Large Aperture

  • Please log in to reply
44 replies to this topic

#1 revans

revans

    Fly Me to the Moon

  • ****-
  • Moderators
  • topic starter
  • Posts: 6,991
  • Joined: 26 Sep 2005
  • Loc: Fitchburg, MA

Posted 12 May 2024 - 04:12 PM

I don't know if this question can even have an answer, but... I notice a tremendous increase in the detail and visibility of faint DSOs using twin white phosphor L3 PVS-14 monoculars with Televue eyepieces on my 5 inch binocular telescope.  Without the NV boost, in my Bortle 6 sky, I can see galaxies down to mag 9.  With the NV boost, I can see galaxies nearly at magnitude 12 and I see a surprising amount of detail. 

 

My unanswerable question is.... without NV boost.... what aperture would I need in order to see what I can using a 5 inch binocular telescope with NV boost?

 

Rick



#2 chemisted

chemisted

    Apollo

  • *****
  • Posts: 1,157
  • Joined: 24 Feb 2012

Posted 12 May 2024 - 04:40 PM

I would guess a dual 16" binocular telescope would be quite comparable.


Edited by chemisted, 12 May 2024 - 04:40 PM.


#3 a__l

a__l

    Fly Me to the Moon

  • -----
  • Posts: 5,115
  • Joined: 24 Nov 2007

Posted 12 May 2024 - 05:45 PM

For the objects you are writing about.
You need good dark skies and that you have good vision. Then you'll see more than you see now for NV. You won't need a larger aperture.



#4 a__l

a__l

    Fly Me to the Moon

  • -----
  • Posts: 5,115
  • Joined: 24 Nov 2007

Posted 12 May 2024 - 05:58 PM

In your observing conditions, most likely any aperture will not help. Due to the fact that the NV spectrum is shifted to the infrared and there is less light pollution there.



#5 Mauro Da Lio

Mauro Da Lio

    Viking 1

  • -----
  • Posts: 889
  • Joined: 12 Sep 2004

Posted 13 May 2024 - 05:09 AM

I confirm a_i's position. Dark sky dark sky dark sky... You might even discover that you see more without NV (for example the outer blue-rich arms of galaxies).

 

M51. It is not yet completely dark. SQM 21.44. Without the intensifier, with the Ethos 21 (163x), one can see the spirals very well, the brightness of the outer halo, and the two tails on opposite sides of the tidal effect. There are several small stars inside. With the intensifier and somewhat lower magnification (115x), the sky background is very bright: the nuclei stand out, but the spirals are practically drowned in the sky background. With the UHXC-S filter, one can see the spirals a little more, but the contrast with the sky background is still very low. The best view with the intensifier is without the UHC-S filter. The spirals, where they can be seen, can be seen quite sharply, but practically, in many areas, they are not visible because they are below the sky level.

 

https://www.cloudyni...eds/?p=12895509

post-5190-0-98434500-1692908808.jpg


Edited by Mauro Da Lio, 13 May 2024 - 05:14 AM.

  • TiSaph likes this

#6 bobhen

bobhen

    Cosmos

  • *****
  • Posts: 8,292
  • Joined: 25 Jun 2005

Posted 13 May 2024 - 05:42 AM

I don't know if this question can even have an answer, but... I notice a tremendous increase in the detail and visibility of faint DSOs using twin white phosphor L3 PVS-14 monoculars with Televue eyepieces on my 5 inch binocular telescope.  Without the NV boost, in my Bortle 6 sky, I can see galaxies down to mag 9.  With the NV boost, I can see galaxies nearly at magnitude 12 and I see a surprising amount of detail. 

 

My unanswerable question is.... without NV boost.... what aperture would I need in order to see what I can using a 5 inch binocular telescope with NV boost?

 

Rick

One of the reasons people gravitate to NV is because they cannot get to a really dark sky or because they don't have the time to get to a really dark sky.

 

I can't answer you question directly but in your Bortle 6 conditions, you have to consider two things... Aperture (light gathering capability) and Contrast.

 

NV offers two advantages over regular glass: The fantastic capability of an image intensifier to multiply photons and therefore multiply images by thousands of times. This is of course something glass cannot do.

 

But the other thing you have to consider is that by adding extremely strong filtration to the optical train, you can add contrast that cannot be added to a regular glass optical train. Hence the need to seek out extremely dark skies for glass-only optical systems.

 

To be seen visually, deep sky objects require both photon gathering and contrast. Adding more and more aperture at your location will do little to add the contrast needed for some of these "at the limit of vision galaxies" to be seen visually.

 

Adding more aperture to a size that equals the photon gathering capability of your smaller aperture plus the intensifier will NOT equal a smaller aperture plus an intensifier because just adding aperture alone does NOT add the contrast needed to go deeper visually. 

 

Bob


  • 25585, Jethro7, dcweaver and 1 other like this

#7 revans

revans

    Fly Me to the Moon

  • ****-
  • Moderators
  • topic starter
  • Posts: 6,991
  • Joined: 26 Sep 2005
  • Loc: Fitchburg, MA

Posted 13 May 2024 - 06:28 AM

One of the reasons people gravitate to NV is because they cannot get to a really dark sky or because they don't have the time to get to a really dark sky.

 

I can't answer you question directly but in your Bortle 6 conditions, you have to consider two things... Aperture (light gathering capability) and Contrast.

 

NV offers two advantages over regular glass: The fantastic capability of an image intensifier to multiply photons and therefore multiply images by thousands of times. This is of course something glass cannot do.

 

But the other thing you have to consider is that by adding extremely strong filtration to the optical train, you can add contrast that cannot be added to a regular glass optical train. Hence the need to seek out extremely dark skies for glass-only optical systems.

 

To be seen visually, deep sky objects require both photon gathering and contrast. Adding more and more aperture at your location will do little to add the contrast needed for some of these "at the limit of vision galaxies" to be seen visually.

 

Adding more aperture to a size that equals the photon gathering capability of your smaller aperture plus the intensifier will NOT equal a smaller aperture plus an intensifier because just adding aperture alone does NOT add the contrast needed to go deeper visually. 

 

Bob

I almost always use H alpha filters on my Televue eyepieces with NV and it really does make a contrast difference no matter whether I'm looking at an emission object or not.

 

Rick


  • Jethro7 likes this

#8 bobhen

bobhen

    Cosmos

  • *****
  • Posts: 8,292
  • Joined: 25 Jun 2005

Posted 13 May 2024 - 06:42 AM

I almost always use H alpha filters on my Televue eyepieces with NV and it really does make a contrast difference no matter whether I'm looking at an emission object or not.

 

Rick

For galaxies (or all non-nebula objects) try a 685 (in heavy light pollution) or 642 (in mild light pollution) IR Pass filter.

 

Bob 


  • revans and Jethro7 like this

#9 revans

revans

    Fly Me to the Moon

  • ****-
  • Moderators
  • topic starter
  • Posts: 6,991
  • Joined: 26 Sep 2005
  • Loc: Fitchburg, MA

Posted 13 May 2024 - 07:28 AM

For galaxies (or all non-nebula objects) try a 685 (in heavy light pollution) or 642 (in mild light pollution) IR Pass filter.

 

Bob 

I sometimes use a 780 IR pass filter.  It is quite a dark filter, but does provide a lot of contrast. I need to order the two that you mention and have been going to for some time now, just got sidetracked and haven't done it yet.

 

Rick



#10 sixela

sixela

    James Webb Space Telescope

  • *****
  • Posts: 17,823
  • Joined: 23 Dec 2004
  • Loc: Boechout, Belgium

Posted 13 May 2024 - 09:09 AM

I confirm a_i's position. Dark sky dark sky dark sky... You might even discover that you see more without NV (for example the outer blue-rich arms of galaxies).


It's really weird, because with my L3 unfilmed and an Astronomik L1 filter at f/4-f/6-ish (prime or prime weakly barlowed) I have the exact opposite experience of yours: I see the tidal tails of the companion with NVD and I don't see them in glass (Apollo 11 or Delos 8, so exit pupils of 2.5 and 1.8mm), and the arm opposite the companion extends much further in the NVD. Of course detail in the brighter parts is a lot easier in the NVD.

[Incidentally, I find the "horizontal" tidal tail "to the left" of the companion in your image a lot easier and much longer than the spurs extending down.]

At the Rassemblement Astronomique du Centre Ardennes I asked roughly 6 people about their opinion, they all agreed with my observation (without hints from me except saying what to look for). I selected the optimal gain for me and the others did not touch it. SQM-L reading roughly 21.4.

I'm at a loss to explain it -- it's not that I'm using day vision and you are using night vision, since the tidal tails require averted vision for me even with the NVD.

Hypotheses left:

-the two filters you're using (no filter and UHC-S) are both non-optimal (no filter because of the airglow, there's a colossal amount of it now, and the UHC-S because it filters too much)
-you're not using the same gain settings as I am
-somehow you tend not to use averted vision in the NVD in the same way as with glass
-for the tidal tails you actually want good gain in yellowish, so a Gen 3 might be better than a Gen 2+
-some other differences in eye/brain system or the NVD.

Edited by sixela, 13 May 2024 - 10:13 AM.


#11 Mauro Da Lio

Mauro Da Lio

    Viking 1

  • -----
  • Posts: 889
  • Joined: 12 Sep 2004

Posted 13 May 2024 - 11:24 AM

 

But the other thing you have to consider is that by adding extremely strong filtration to the optical train, you can add contrast that cannot be added to a regular glass optical train. Hence the need to seek out extremely dark skies for glass-only optical systems.

 

That works only for H-alpha. Otherwise NV under Bortle 6 is like Aperture under Bortle 6. In both cases they do not compare to Bortle 1-2.



#12 Mauro Da Lio

Mauro Da Lio

    Viking 1

  • -----
  • Posts: 889
  • Joined: 12 Sep 2004

Posted 13 May 2024 - 11:39 AM

It's really weird, because with my L3 unfilmed and an Astronomik L1 filter at f/4-f/6-ish (prime or prime weakly barlowed) I have the exact opposite experience of yours: I see the tidal tails of the companion with NVD and I don't see them in glass (Apollo 11 or Delos 8, so exit pupils of 2.5 and 1.8mm), and the arm opposite the companion extends much further in the NVD. Of course detail in the brighter parts is a lot easier in the NVD.

That was using the OVNI-M, SQM ~21.5, no filter, 24" dobsonian (this quote was from this discussion https://www.cloudyni...entry12895509).

It was before finding the issues with the airglow and discovering that IR-cut works better under dark sky.

 

However, IR-cut so far works better with Photonis than with the OVNI ---"the sky background is very bright" (as far as I can remember, because I have yet to carry out a side-by-side comparison on the same targets on the same day and location and under dark sky). I have an IR-cut filter that cuts at about 700 nm (the Astronomik cuts at 720). I will try again as soon as the meteo allows me to go under 21.5.

 

I have no legal chance to try a L3-Harris, but I do suspect it would be the best of the three. 


Edited by Mauro Da Lio, 13 May 2024 - 11:43 AM.


#13 bobhen

bobhen

    Cosmos

  • *****
  • Posts: 8,292
  • Joined: 25 Jun 2005

Posted 13 May 2024 - 01:26 PM

That works only for H-alpha. Otherwise NV under Bortle 6 is like Aperture under Bortle 6. In both cases they do not compare to Bortle 1-2.

Not my experience. You can't add contrast with just glass but you can with NV. Without a filter, in Bortle 6 the intensifier will also intensify the light pollution. With a filter, the background is darker but there are still plenty of photons from the image that can be "multiplied" by the intensifier so the target now stands out from the filtered darker background much better. Can't be done with just glass. 

 

Bob


Edited by bobhen, 13 May 2024 - 01:36 PM.

  • revans, chemisted and firemachine69 like this

#14 Mauro Da Lio

Mauro Da Lio

    Viking 1

  • -----
  • Posts: 889
  • Joined: 12 Sep 2004

Posted 13 May 2024 - 03:48 PM

Which filter?



#15 sixela

sixela

    James Webb Space Telescope

  • *****
  • Posts: 17,823
  • Joined: 23 Dec 2004
  • Loc: Boechout, Belgium

Posted 13 May 2024 - 04:06 PM

That was using the OVNI-M, SQM ~21.5, no filter


Yeah, no argument from me then.

#16 bobhen

bobhen

    Cosmos

  • *****
  • Posts: 8,292
  • Joined: 25 Jun 2005

Posted 14 May 2024 - 05:05 AM

Which filter?

642 or 685 IR Pass.

 

Bob



#17 PEterW

PEterW

    Gemini

  • *****
  • Posts: 3,455
  • Joined: 02 Jan 2006
  • Loc: SW London, UK

Posted 14 May 2024 - 07:11 AM

In heavy light pollution go long. If you want nebulae then use a dedicated narrow hydrogen filter.

Peter
  • Joko likes this

#18 sixela

sixela

    James Webb Space Telescope

  • *****
  • Posts: 17,823
  • Joined: 23 Dec 2004
  • Loc: Boechout, Belgium

Posted 14 May 2024 - 09:06 AM

And in a better sky (Bortle 3-4 or better) go short (IR block from 720nm longwards). For a worse Bortle 4 no filter is sometimes best (all 'our mileage may vary' because it even depends on the amount of airglow, which also depends on the solar activity).

Edited by sixela, 14 May 2024 - 09:07 AM.

  • Joko likes this

#19 Mauro Da Lio

Mauro Da Lio

    Viking 1

  • -----
  • Posts: 889
  • Joined: 12 Sep 2004

Posted 14 May 2024 - 01:11 PM

1) The pristine dark sky is as dark as 22 mpsas in the visual band. A B3 sky may be about 21.5.

2) Airglow in the IR is as bright as about 20 (and even worse if your NVD extends to very long wavelengths).

3) Objects are always the same (less extinction). For example NGC 6946 is 23.73.

 

Now, put everything together.

 

Case A) polluted sky, say SQM 18.5.

a.1) If you use NV+IR-pass then you have this contrast: 23.7 - 20 (NGC6946). i.e. it is 3.7 magnitudes darker

a.2) If you NV and do not use any filter it is 23.7-18.5, i.e., 5.2 darker. 

 

Case B) Be sky, say SQM 21.5.

b.1) If you use IR-cut then you have this contrast: 23.7-21.5, i.e., 2.2 magnitudes still darker. 

b.2) If you use no filter the contrast is 23.7-20, i.e. 3.7 darker. 

b.3) Visually the contrast is 23.7-21.5 = 2.2 (and NGC is faintly glowing)

 

Comments:

- a.2 has relatively better contrast than a.1. However, at 3.7 magnitudes NGC 6946 still not be visible anyway. 

- b.3 is better than both (and in fact NGC6946 is faintly visible)

- b.2 is not visible

- b.1 is similar to b3. for contrast but gives higher resolution.

 

Conclusion: IR-pass under heavily polluted sky do not compare to dark sky, both visually and with NV+IR-cut. You can see more under dark sky.


Edited by Mauro Da Lio, 14 May 2024 - 01:14 PM.


#20 revans

revans

    Fly Me to the Moon

  • ****-
  • Moderators
  • topic starter
  • Posts: 6,991
  • Joined: 26 Sep 2005
  • Loc: Fitchburg, MA

Posted 14 May 2024 - 05:51 PM

I'm sure dark skies always let you see deeper, but if you happen to be in Bortle 6 (like me) and don't travel, then the best you can do is use NV with some sort of filter to increase contrast.  The only question for me, is what would be the best instrument to put an NV eyepiece on.  In a light polluted sky, does it do better as aperture increases or is there a law of diminishing returns.  I haven't been to a dark sky site in years, but I suspect using NV there would show more depth than just glass alone.

 

Rick


  • 25585 likes this

#21 t.mihai147

t.mihai147

    Mariner 2

  • *****
  • Posts: 248
  • Joined: 08 Jun 2020
  • Loc: Bucharest, RO

Posted 15 May 2024 - 01:02 AM

 The only question for me, is what would be the best instrument to put an NV eyepiece on.  In a light polluted sky, does it do better as aperture increases or is there a law of diminishing returns.  I haven't been to a dark sky site in years, but I suspect using NV there would show more depth than just glass alone.

 

Rick

I hope my reply is addressing your above question:

I am learning myself a lot from reading various posts and then trying to experiment.

As far as I have seen, if you have different telescopes with different focal lengths and apertures (so different speeds), for the same camera or NV or observer and in the same sky condition, the variable in signal received by sensor or human eye depends on the speed only. The scale of the target is of course different and the focal length is what determines that but as soon as you match the target with FL, only the speed of the optical system (that is telescope diameter plus reducer or barlow or afocal system) is what it counts.

 

I have just red a post (https://www.cloudyni...r/#entry9349503) that explains it very well from theory side and if you take out all the variables that are the same for one particular telescope and one observer (camera or NV or human eye), then we have simplified the sensitivity ratio as:

 

Attached Thumbnails

  • Untitled.png

  • dcweaver likes this

#22 PEterW

PEterW

    Gemini

  • *****
  • Posts: 3,455
  • Joined: 02 Jan 2006
  • Loc: SW London, UK

Posted 15 May 2024 - 01:57 AM

1) The pristine dark sky is as dark as 22 mpsas in the visual band. A B3 sky may be about 21.5.
2) Airglow in the IR is as bright as about 20 (and even worse if your NVD extends to very long wavelengths).
3) Objects are always the same (less extinction). For example NGC 6946 is 23.73.

Now, put everything together.

Case A) polluted sky, say SQM 18.5.
a.1) If you use NV+IR-pass then you have this contrast: 23.7 - 20 (NGC6946). i.e. it is 3.7 magnitudes darker.
a.2) If you NV and do not use any filter it is 23.7-18.5, i.e., 5.2 darker.

Case B) Be sky, say SQM 21.5.
b.1) If you use IR-cut then you have this contrast: 23.7-21.5, i.e., 2.2 magnitudes still darker.
b.2) If you use no filter the contrast is 23.7-20, i.e. 3.7 darker.
b.3) Visually the contrast is 23.7-21.5 = 2.2 (and NGC is faintly glowing)

Comments:
- a.2 has relatively better contrast than a.1. However, at 3.7 magnitudes NGC 6946 still not be visible anyway.
- b.3 is better than both (and in fact NGC6946 is faintly visible)
- b.2 is not visible
- b.1 is similar to b3. for contrast but gives higher resolution.

Conclusion: IR-pass under heavily polluted sky do not compare to dark sky, both visually and with NV+IR-cut. You can see more under dark sky.

Given the highly nonuniform spectral shapes of the NV tubes and the light pollution and sky glow I’m not sure such a simple calculation is entirely valid. Best to understand what wavelengths the majority of the photons you don’t want are and then filter accordingly so they don’t get amplified. For me that would nearly always be a long pass to remove all the urban visible muck. Sky transparency is also an influencing factor that can vary a lot, some nights some nebulae are easy, some much less so. Having a few options available would help find the best for a given object and local conditions.

#23 bobhen

bobhen

    Cosmos

  • *****
  • Posts: 8,292
  • Joined: 25 Jun 2005

Posted 15 May 2024 - 05:49 AM

I'm sure dark skies always let you see deeper, but if you happen to be in Bortle 6 (like me) and don't travel, then the best you can do is use NV with some sort of filter to increase contrast.  The only question for me, is what would be the best instrument to put an NV eyepiece on.  In a light polluted sky, does it do better as aperture increases or is there a law of diminishing returns.  I haven't been to a dark sky site in years, but I suspect using NV there would show more depth than just glass alone.

 

Rick

Like you, I live in a light polluted location and cannot really get to a dark sky anymore, I have in the past, but not now.

 

I can only give you, my experience. Here are 2 examples.

 

Galaxy 891 was invisible at my location with a C11 using just glass eyepieces. With my 120mm refractor and my intensifier and a 685 Pass filter, I can just glimpse the galaxy. It's definitely not in-your-face visible but once spotted, you can repeat the observation. With the C11 used visually, only few stars in cluster 2158 were observed. With the smaller 120mm refractor, the cluster is completely resolved. A 120mm refractor has less than half the aperture of the C11. So even with non-nebula objects, NV plus a filter is much better than visual when mild or heavy light pollution is part of the equation.

 

How big should you go? Just like visual, NV will do better in light pollution with larger aperture. And, just like visual, the impact or visual gains will diminish as aperture increases.

 

As our ages increase, it's really about what you can handle physically and not about what another 3 or 4 more inches of aperture will show you. Keep in mind, the intensifier has already done the heavy lifting. 

 

I like one wide field scope and one scope with a longer FL and some aperture. An SCT is attractive because they are compact tubes. Of course, a Dobsonian that will breakdown is also attractive. Do you want to setup and teardown a Dob each time?

 

Get what you can handle first. Telescopes don't get lighter as we age.

 

I'm just thrilled that with my small refractors and my C8 I can see the Horse Head Nebula and so much more and on any clear night. That's the power of NV. Without NV, so many objects would be out of reach because of my age and my location.

 

Bob


Edited by bobhen, 15 May 2024 - 06:03 AM.

  • Second Time Around likes this

#24 revans

revans

    Fly Me to the Moon

  • ****-
  • Moderators
  • topic starter
  • Posts: 6,991
  • Joined: 26 Sep 2005
  • Loc: Fitchburg, MA

Posted 15 May 2024 - 10:03 AM

Like you, I live in a light polluted location and cannot really get to a dark sky anymore, I have in the past, but not now.

 

I can only give you, my experience. Here are 2 examples.

 

Galaxy 891 was invisible at my location with a C11 using just glass eyepieces. With my 120mm refractor and my intensifier and a 685 Pass filter, I can just glimpse the galaxy. It's definitely not in-your-face visible but once spotted, you can repeat the observation. With the C11 used visually, only few stars in cluster 2158 were observed. With the smaller 120mm refractor, the cluster is completely resolved. A 120mm refractor has less than half the aperture of the C11. So even with non-nebula objects, NV plus a filter is much better than visual when mild or heavy light pollution is part of the equation.

 

How big should you go? Just like visual, NV will do better in light pollution with larger aperture. And, just like visual, the impact or visual gains will diminish as aperture increases.

 

As our ages increase, it's really about what you can handle physically and not about what another 3 or 4 more inches of aperture will show you. Keep in mind, the intensifier has already done the heavy lifting. 

 

I like one wide field scope and one scope with a longer FL and some aperture. An SCT is attractive because they are compact tubes. Of course, a Dobsonian that will breakdown is also attractive. Do you want to setup and teardown a Dob each time?

 

Get what you can handle first. Telescopes don't get lighter as we age.

 

I'm just thrilled that with my small refractors and my C8 I can see the Horse Head Nebula and so much more and on any clear night. That's the power of NV. Without NV, so many objects would be out of reach because of my age and my location.

 

Bob

Interesting that you mention the horsehead nebula.  It won't be back in the sky for some months, but I had been using it as a test object for my NV setup.  In a 5 inch binocular telescope, 15mm eyepieces coupled to NV, I can easily see the nebulous curtain all around the area of the nebula, but the dark horsehead shape is not evident.  One of my goals is to see it well with NV and that began the impetus for larger aperture to put my NV eyepieces on.  It isn't visible in my C5 with NV.  I had my C6 tied up with hyperstar at the time and couldn't try it.  And I didn't try with my C9.25 which was set up for imaging and I didn't want to disturb it.

 

My thinking was that maybe I should keep a 12 inch Dob around and I very nearly bought an Obsession 12.5 classic.  But after sleeping on it, that seemed extravagant and premature considering I hadn't tried the larger scopes I own with NV yet. 

 

I'm crazy in that I like to keep a particular rig for a particular purpose and leave it setup that way.  I don't like a rig to multi-task unless absolutely necessary.  

 

I've thought of this $1500 eyepiece (SmartEye by Pegasus Astro).  But that really isn't observing.  I think of it as a nice possibility for entertaining visitors interested in astronomy, but not so much for me personally. My next step, anyway, now that my C9.25 is freed up from imaging, is try it with NV.  But I'll have to wait quite a while until the horsehead comes around again.

 

Rick



#25 sixela

sixela

    James Webb Space Telescope

  • *****
  • Posts: 17,823
  • Joined: 23 Dec 2004
  • Loc: Boechout, Belgium

Posted 15 May 2024 - 10:07 AM

Kind of weird...I can see the Horse Head Nebula as a distinct notch at 3x (with an f/1.6 objective) using an NVD in my Bortle 8 sky and a 6nm H-alpha filter. It's one of the easier objects for an NVD. Of course aperture really helps to see it as more than a notch, and it looks a lot better in my 20" than in my 6" (and better stil at darker sites).

A 15mm eyepiece in an afocal stack on a f/10 SCT seems an awfully large magnification for it. I'd tend to use the ubiquitous TV67 for that, and even that is kind of slowish for it.

I can only reconcile your post with a lack of using a H-alpha filter at all, and then it becomes a really hard object instead of one of the easier ones.

Edited by sixela, 15 May 2024 - 10:10 AM.



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