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MOD3 WP Honeycomb

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#1 jay.i

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Posted 19 August 2020 - 11:23 AM

Hey all,

 

I just received my MOD3 and with extreme excitement, unboxed it and gave it a test in a closed bathroom. Oh good heavens this is amazing!! It's like someone turned the lights on!

 

But I noticed one thing, after cracking the door open to see how low I could go on the gain, playing around with it. I noticed a honeycomb pattern on brighter areas. I feared that I damaged the tube somehow so I shut the unit off, shut the door, waited a minute, and turned it back on. Still a honeycomb pattern in some spots. In darker areas I don't notice it, but then when panning I see the honeycomb pattern sort of reducing resolution in a way, like I can tell there is something in the way of the image. It's almost hard to get my eyes to focus on the image instead of the honeycomb pattern which seems like a screen in front of the image.

 

On the IR illuminator mode (which is AWESOME) it's clear as day, basically the entire image looks like it has a honeycomb fence in front of it. It would be impossible not to see it even at low gain based on how effective the IR illuminator is.

 

I did not notice this pattern in my initial testing before I decided to crack the bathroom door (not looking outside ofc). I was obviously focused on the image and what I could see and how effective the NV device really is. I have to think I would have noticed the honeycomb pattern, but maybe it just didn't get quite bright enough for me to notice it before? I didn't look directly at any bright light source; I can't have possibly damaged the tube by allowing a little more light into the bathroom.

 

Based on some quick searching, it seems this is not uncommon. However, some people say it's pretty minor in their units. I think it's pretty obvious in mine. What should I do? I spent some real dough on this device and I want to be happy with it, but I just don't know how much other people are seeing and if mine is any more than theirs and if I could expect a tube that exhibits less of the honeycomb effect. I would love to not have to ship this back to UNV and wait who knows how long for another unit/tube, if they're even willing to exchange it for me.

 

What do I do? Can I even expect a unit that has a much more subtle honeycomb? :(



#2 PEterW

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Posted 19 August 2020 - 11:34 AM

Interested to hear e opinion as I find that if I pan slowly I can see more dark nebulous detail as the honeycomb pattern tends to affect the details if I hold still.

Peter

#3 Eddgie

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Posted 19 August 2020 - 12:27 PM

Fixed pattern noise (honeycomb) is common and will show on many tubes when the are used against a bright, even background.

 

They are rarely an issue on most DSOs but sometimes will show on large bright DSOs.  You can see it in this picture looking around the bright overexposed core.  Now otherwise, I never saw the effects of honeycomb anything dimmer than this, but sometimes on the Milky Way under light polluted sky, if I looked for it, 

 

MX on M42.jpg

 

Don't panic.  Looking into a bright scene is not only not typical for using NV, but not desirable due to the wear on the tube.  In most cases though, except when the sky is bright, you probably won't notice the fixed pattern noise.  Give it a chance by using it the way it was intended to be used...


Edited by Eddgie, 19 August 2020 - 01:13 PM.


#4 jay.i

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Posted 19 August 2020 - 12:45 PM

I appreciate the response Eddgie. I'm definitely going to use it on the night sky before I make any final judgments. I can definitely see running into it on brighter DSOs but I might be able to ignore it. What do people who buy NV for terrestrial use think about this? Surely you're going to use it around areas lit dimly by a distant streetlight or whatever. The pattern can obscure detail, and with the IR illuminator it's extremely obvious in the entire frame from edge to edge; I can imagine using the illuminator in tactical situations and having a mesh screen in front of the image would seem distracting to me. Do people really just learn to "look past it"? I know it is something that I will have to learn to ignore and not let bother me, like lateral CA for example (super easy for me to see, it's everywhere, can't let it bother me though).

 

In doing some more testing, it seems that there is a sweet spot (or salty spot?) on the gain where I find it easy to see the honeycomb without looking for it, but with the gain lower, or higher, it's not as obvious. With fairly high gain, it's actually harder to see, oddly enough. When gain is low enough to have very little scintillation, I can see the honeycomb on any lit part of the scene.

 

Another thing too - I wanted to let the unit cool down from some use and see if the honeycomb is more present after the unit has been on for a few minutes. In my tests I found that I had a hard time seeing the pattern at most gain settings for the first 30-60 seconds, but as my eye adjusted to the image, the pattern became more apparently seen. I think this has more to do with my eye adjusting - I don't think it's related to device warm-up or anything like that.

 

I'm crossing my fingers for a clear night tonight so I can put it to work. It's been pretty clear here lately so I'm sure tonight I'll have clouds. I don't have a reducer or afocal setup to test with my telescopes so I'll have to settle for 1x and 2x, which may be an issue because I have plenty of streetlights below my apartment balcony and all around the area. I will of course try my telescopes but they won't be fast enough to be bright at lower gain settings where I might see the pattern (because again it's less visible at higher gain from what I can tell).

 

The more testing I do, the less upset I become. It was super jarring at first and completely killed the giddy child with a new toy feeling and replaced it with a just broke my new toy feeling. But again as I keep testing it in the bathroom, I feel like I am able to ignore it a little more. It will never be invisible to me which is sad because I didn't even though this was a thing to expect with L3 tubes, but I think it's possible I could learn to accept it and move on and enjoy the NVD for the reasons I bought it in the first place.


Edited by jay.i, 19 August 2020 - 12:48 PM.


#5 Eddgie

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Posted 19 August 2020 - 01:19 PM

As I said, fixed pattern noise is usually only visible when you are looking at brighter scenes with even illumination.  For example, if you look at a light polluted sky you will see chickenwire in many tubes. 

For normal terrestial use, it should be invisible, and for most astronmy use with filters, it should be invisible. 

 

You are fixating on the chickenwire. On the fast majority of celestial subjects, you will not see it even if you are looking for it.

 

If you do, then yeah, that could be an issue, but again, for terrestial use it should be invisible and for most DSO and nebula you won't see it.  M42 is unusually bright as is a light polluted sky when no long pass filter is used.



#6 Mazerski

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Posted 19 August 2020 - 01:24 PM

Jay,

 

I have Mod3 WP with Gain and see honeycomb and it has no effect on observing in any mode... hand-held and with scopes.



#7 jay.i

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Posted 19 August 2020 - 01:49 PM

Jay,

 

I have Mod3 WP with Gain and see honeycomb and it has no effect on observing in any mode... hand-held and with scopes.

I get what you're saying, but people say that about chromatic aberration all the time. What they're really saying is it doesn't bother them, that it doesn't affect their enjoyment of the observation. But it's hard to know how much they're seeing and how much they're willing to put up with. It could be that my tube shows a prominent honeycomb structure and yours shows hardly any. Or, ours show roughly the same, and you just don't let it bother you, or it doesn't show up for the subjects you observe.

 

I sadly live in a Bortle ~8 which means looking up at a light polluted sky a lot of the time. I'm moving soon to a place with slightly darker skies, but much less visible sky from the property. Regardless, I won't have dark skies available to me often, which means I may be seeing a lot more honeycomb than others here who live or observe frequently from Bortle 4 or under.

 

We will see! I'm hopeful.



#8 PEterW

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Posted 19 August 2020 - 02:43 PM

If you have gain control the turn the brightness down and you won’t see it. If you have an old tube with no gain control then adding more filters can help darken the background.

Peter

#9 Mazerski

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Posted 19 August 2020 - 02:44 PM

I have east coast LP to deal with but up don’t panic yet. 

 

Suggested filter use for LP:

 

== 685 IR for globulars and galaxies

== 642 IR for certain bright nebula like M42 and to see the Milky Way clouds with lots of stars

== 610 IR with a higher focal ratio - f/8 or so

 

== 6, 7 or 12 Ha for emission and each one has its strengths 



#10 Jeff Morgan

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Posted 19 August 2020 - 09:33 PM

It is not a defect. It is the internal structure of the device. Therefore they all have it, and under the right conditions (bright background and high gain) it may be visible.

 

Turn down the gain.

 

Also makes me wonder if higher sensitivity tubes are more susceptible to it?



#11 jay.i

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Posted 19 August 2020 - 11:24 PM

It is not a defect. It is the internal structure of the device. Therefore they all have it, and under the right conditions (bright background and high gain) it may be visible.

 

Turn down the gain.

 

Also makes me wonder if higher sensitivity tubes are more susceptible to it?

As I said earlier, higher gain actually made it less visible. It's easier to see with a clean image with less scintillation and that is somewhere around the 50% gain mark.


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#12 jay.i

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Posted 19 August 2020 - 11:39 PM

I tested the MOD3 under the night sky tonight and despite clouds and plenty of light pollution to go around, I did not see any honeycomb pattern at any gain setting whatsoever (except with the ENVIS at 1x with the brightly lit sky essentially acting as a flat backlit surface which makes the pattern easy to see). If I can get out to my club's Bortle 3 this weekend I might be able to actually find some nebulae, but nothing as bright as M42 of course. In actual observing with filters, or in darker skies even without a filter, I don't think I'll see the honeycomb.

 

The more I test this the more confident I become that it is something I can ignore. I had to test it when I got it, which meant indoors, in a place with walls and other flat surfaces. Of course! I'm going to see how it fares in just a dark park/wooded area as well to see if I can notice the honeycomb in that setting. If not, I think I won't notice it in basically any realistic scenario, which is great, and I hope is the case.


Edited by jay.i, 20 August 2020 - 12:19 AM.

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#13 PEterW

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Posted 20 August 2020 - 03:07 AM

Is the 642nm that much better at showing stuff (and stamping out urban light pollution) than the 685nm? Probably has a faster cut-on as it’s dielectric?!

Peter

#14 Mazerski

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Posted 20 August 2020 - 08:04 AM

Peter - on the 642nm, for me with east coast US sky, the 642 allows me to easily see the MW clouds. The North American is not visible with 642 but nebulosity of NGC40, Eskimo, M17, M8

and epically M42 is visible while showing a lot of stars. The 642 is not replacing an Ha filter but it’s just a different view.

 

The 685 shows the sky darker, less to no nebulosity (depends) and makes for better contrast on globulars and galaxies.



#15 PEterW

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Posted 20 August 2020 - 09:50 AM

How bad is your sky? I am in an edge of city location skies around mag18.5-19. I don’t have gain control, so slightly worried about image brightness, but more mw clouds would be good.

Thank

Peter

#16 jay.i

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Posted 20 August 2020 - 10:15 AM

My skies are similarly bright (between 18.5-19 on a good night) and I was under the impression that 642nm was for more like 19.5-20 skies (~Bortle 5-6). I can definitely say I didn't see any hint of MW cloudiness with my 685nm filter last night but it darkened the sky nicely while still showing thousands of stars in the FOV. If my skies were slightly darker I think I'd experiment with a 642nm filter.



#17 Mazerski

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Posted 20 August 2020 - 10:20 AM

My location is southwest of Baltimore and northeast of Washington DC. Patio at house is protected from lights but the sky is ruined. Looking at the bortle scale, my area is an 8 and I don’t know anything about SQM. I have seen a map that shows my area bordering color white which = bad news. 
 

I have PVS7 White P and no gain and Mod 3 White P with gain and rarely mess with it. 



#18 Mazerski

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Posted 20 August 2020 - 10:32 AM

Jay,

 

The 685 is overall too restrictive (in my area) to see MW clouds / nebulosity. Some minor nebulosity shows  in the Sagittarius area but the 642 does a much better job. The 610 allows too much light in for my area and contrast is lost as the view is way too bright.

 

For the upcoming winter, look at M42 with Ha filter then try 685 then 642. The differences are stark.



#19 jay.i

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Posted 20 August 2020 - 10:36 AM

Jay,

 

The 685 is overall too restrictive (in my area) to see MW clouds / nebulosity. Some minor nebulosity shows  in the Sagittarius area but the 642 does a much better job. The 610 allows too much light in for my area and contrast is lost as the view is way too bright.

 

For the upcoming winter, look at M42 with Ha filter then try 685 then 642. The differences are stark.

Well it looks like I might be getting a 642 then. Ugh. lol.gif



#20 Mazerski

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Posted 20 August 2020 - 10:43 AM

Overall, I think the 642 is the best filter, can see Some nebulosity, globulars, galaxies and star fields.

The filter does not replace an Ha as Ha is needed for emission nebula. The 642 allows nebulosity from a handful of nebula to peek thru but not like the Ha filter.

 

My opinion with crappy east coast mid-Atlantic Sky



#21 Jeff Morgan

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Posted 21 August 2020 - 01:00 AM

Doing research on a new tube, and I had forgotten what a good resource ar15.com was. While there I found a link for YouTube videos. This one is about cosmetics, briefly touches on honeycomb. 

 

https://www.youtube....?v=XfwrDoOP_K4 



#22 kennyrichmond

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Posted 21 August 2020 - 07:23 AM

It is not a defect. It is the internal structure of the device. Therefore they all have it, and under the right conditions (bright background and high gain) it may be visible.

 

Turn down the gain.

 

Also makes me wonder if higher sensitivity tubes are more susceptible to it?

To the OP, this statement that, "...they all have it.",  is completely untrue.  Fixed patterns in NV devices are serious defects and should be disclosed by a seller.  "Therefore" return it, and get your purchase price back before it is too late.  Secondly, the suggestion that any bright nighttime astronomical subjects will damage a NV tube is likewise a misrepresentation.   NV tubes, particularly thin-filmed, auto-gain are constantly employed over densely lit urban flight paths without damage...or distracting halos.

 

Good luck with the warranty. 



#23 Jeff Morgan

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Posted 21 August 2020 - 10:26 AM

To the OP, this statement that, "...they all have it.",  is completely untrue.  Fixed patterns in NV devices are serious defects and should be disclosed by a seller. 

https://tnvc.com/ufa...ern-noise-fpn/ 



#24 jay.i

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Posted 21 August 2020 - 10:33 AM

Based on more use last night, I didn't see any when using it through the telescope at prime focus. When I attached my 50mm f/1.3 lens, even with the 6nm H-a filter, the sky was bright enough to show the honeycomb pattern at medium gain. If I raised the gain a bit (obviously adding more noise) it was less apparent but still there if I chose to focus on it. Less bothersome in practice than testing in a bathroom, for sure. But not invisible.

 

Interestingly enough, the tube report I got with my unit has some checkboxes for things that are or aren't applicable/tolerable. There is an UNCHECKED check box (meaning not applicable) for "Chicken wire / dark lines acceptable". This would suggest that not every tube exhibits it. That or it's not visible at a certain light level, which is not defined in that area. So, I'll be giving UNV a call to see what my options are.



#25 M44

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Posted 21 August 2020 - 12:32 PM

Overall, I think the 642 is the best filter, can see Some nebulosity, globulars, galaxies and star fields.

The filter does not replace an Ha as Ha is needed for emission nebula. The 642 allows nebulosity from a handful of nebula to peek thru but not like the Ha filter.

 

My opinion with crappy east coast mid-Atlantic Sky

Your experience with 642 exactly mirrors mine. 642 is much more detail than 685 that I tried in my Los Angeles suburban skies.




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