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Wide Angle Night Vision on meteors and such

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#1 john hraba

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Posted 25 June 2020 - 01:39 PM

My question is has anyone tried wide angle lenses on a night vision device with the intent of observing meteors and other phenomena that would benefit from such wide angle coverage.  By wide angle lens I mean any lens having a focal length less than 25mm. I would appreciate any information on specific lenses and filters used as well as observations and technique.  With the Perseid meteor shower peaking on the night of August 12th this seems like a good time to have this discussion.  I had seen this topic mentioned in another current thread and rather than hijack that thread I started this one.



#2 TOMDEY

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Posted 25 June 2020 - 02:06 PM

Yea, I did Night Vision video of the Leonid Meteor Storm Nov 17/18 Y2001. The lens was a 13mm C-mount and worked well.    Tom

 

~click on~ >>>

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  • 34 leonid storm video tom.jpg
  • 35 leonid storm video tom.jpg


#3 john hraba

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Posted 27 June 2020 - 01:53 PM

Yea, I did Night Vision video of the Leonid Meteor Storm Nov 17/18 Y2001. The lens was a 13mm C-mount and worked well.    Tom

 

~click on~ >>>

Tom,

 

Your setup looks like an efficient way to capture and record meteor trails using video.  I was wondering if you remember the particulars of the 13mm lens you used specifically the manufacturer,  f/# and the sensor size covered.  I expect the angle of sky covered by the setup was between 70 and 85 degrees, please correct me if I am wrong.  Also I am wondering if at any point you used the 13mm lens on the NV unit with an eyepiece to look at meteors and perhaps the sky in general.  Your description and impressions of what you saw would be appreciated since most use of NV these days seems to be at 1X and greater.



#4 TOMDEY

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Posted 27 June 2020 - 05:07 PM

It may have been this lens. I have hundreds of lenses all over the place. That old NV is the Collins Optics gizmo that was nice in some ways, and very expensive at the time... long long ago. I think I spent well over $5K on it. Two problems with it. The custom relay lens (phosphor output to camera array) was pretty clunky, and the rectangular portion of the 18mm diam sampled by the array was unnecessarily constricted. It was also very heavy.

 

The several devices that I use now, at 1x... all have the dedicated 1x objective lenses and eyepieces. I actually do true binocular at 1x... two separate tubes, one for each eye. Spectacular!    Tom

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  • 45 cannon 13mm F1.5 lens for Night Vision Tom's.jpg


#5 hoof

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Posted 27 June 2020 - 06:03 PM

Interesting idea. I have a mod3c, nikon lens adapter, and a shelf full of DSLR lenses. Might try my 8mm crop-frame fisheye F/3.5 lens for meteor tracking some day.

I have played with sub 25mm lenses, the main issue is the vertigo issue with the visuals not slewing vs your head “correctly” leading to discomfort. And the rectilinear distortion is a factor to. The fisheye does mitigate the latter, but not the former.

#6 Alien Observatory

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Posted 27 June 2020 - 10:02 PM

Perseid Meteor Shower using a Tokina 11 to 16 Zoom with a ZWO 071 Cam...10 second single image...Full frame and Crop / Zoom....Pat Utah smile.gif

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  • Perseid Shower 8-2016.jpg
  • Life and Death of a Persaid.jpg

Edited by Alien Observatory, 27 June 2020 - 10:10 PM.


#7 cnoct

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Posted 29 June 2020 - 09:19 AM

That 13mm, yea wow is that wide for the Collins.

 

Peculiar lens for sure being both 13mm and f/1.5, not an expected set of values.  

 

Like that you've documented your systems and components over the years, really helps when looking back. 

 



#8 SMark

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Posted 30 June 2020 - 12:21 AM

I think watching for meteors may be my most frequent NV activity. I have an ANVIS binocular with class A 1x objectives. Even the weaker meteor showers are worth watching with NV.
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#9 Eddgie

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Posted 30 June 2020 - 09:45 AM

I think watching for meteors may be my most frequent NV activity. I have an ANVIS binocular with class A 1x objectives. Even the weaker meteor showers are worth watching with NV.

Yeah, I use my Mod 3 binoculars a lot and even when there are no showers, I find them to be really superb catching meteors. Most nights (weather permitting) I go out with my binoculars for ten or fifteen minutes and it is pretty typical to see at least one or two meteors.

 

The best thing though is that in the days before or after a shower, I almost always see more meteors than I would see during the peak of the shower before I started doing night vision. The binoculars are outstanding for this application.

There is one major piece of advice I would give.  If the meteor appears very bright, train yourself to immediately drop the BV from your eyes (or NV device) and look at it visually.  NV Is fantastic for seeing faint meteors, but when the really bright ones streaks across the sky, if you follow your instinct to track it with NV, you will miss the colors that often flash when the big, grazing ones streak across the sky. I would warn that this is hard to do.  The instinct is to follow it, but if one sees the meteor start to spark or get very bright in the NV device, lower it and look with the eye.  Since I have conditioned myself to do this, I have caught some really colorful meteors.



#10 nimitz69

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Posted 30 June 2020 - 10:52 AM

I have used my MOD3 specifically for a meteor shower yet but I’ve seen meteors when doing 1x handheld viewing lots of times with either my ENVIS or Fujinon 25mm f/.85 lens’

#11 SMark

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Posted 30 June 2020 - 02:35 PM

One of the great things about watching meteors with night vision is that you really get a good perception of the different types of meteors. Some of course are very fast streaks across the sky, but my favorites are what I called the “slow burners.” Usually they are larger and they slow down as they burn out, and you can see fragments burning off the core as it burns out. It’s fascinating to watch those.

During meteor showers, it’s not uncommon to see five or six meteors at one time. I can only imagine how many I could see if I had an even wider field of view.

And also keep in mind, I’m watching these meteor showers in the middle of my suburban city. I would probably see three or four an entire evening without night vision.
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#12 SiriusLooker

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Posted 03 July 2020 - 03:57 AM

A side note also is the (after math) of a bright streaker. That can be just as impressive to see, and in some cases for a minute or more later,-- the very detail smoke trail left behind is remarkable in NV.. Having the look of Veil nebula on a large scale. Those few that I have seen are still implanted in my feeble mind of the NV.. I too have recently acquire multiple ultra wide lens just for this purpose, to view meteor showers and the like.--having 10mm Zeiss, 12mm Zeiss, 16mm,. I have been pushing my NV. lately to its upper most (flexible limit), and hope to present that very soon here. For the record, being very fortunate, the brightest Meteor I have seen in over 50yrs, gracing over 3/4quarters of the sky, seen over multiple states, and still quite vivid in my mind, -- happens to be on film!.


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#13 john hraba

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Posted 03 July 2020 - 05:15 PM

Thank you to those of you who responded to this post.  Those responses have made a couple of things clear:

 

1. There can be substantial benefit to meteor observing by using a NV device.

 

2.  Not a lot of people have tried using lenses with focal lengths less than 25mm on their NV devices.

 

This sounds like an area that may be worth further exploration to that end I have ordered a Fujinon CF16HA-1.  This lens is a 1" format, 16mm focal length, manual lens made for C-mount machine vision cameras.  The lens should give me a field of view on the sky of about 65 degrees. I will post my experiences with this lens once I have had a chance to use it on my MOD3-C.

 

One other possible application of a 16mm lens, that I thought of, was to use it afocally with a Panoptic eyepiece.  The Panoptic has an angle of view of 68 degrees and the 16mm lens has an angle of acceptance of about 65 degrees so it should cover the majority of the Panoptic field compressing that field into the 40 degree field of the MOD3-C. I believe the combination should act like using a 0.6 focal reducer on the Panoptic.  There is, of course, also the issue of adapting the 16mm lens' 49mm front thread to the eye end of the Panoptic.



#14 GrahamDFyffe

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Posted 03 July 2020 - 08:22 PM

Let me know how the CF16HA works out. I too am looking for a short focal length objective that will fully illuminate the sensor.



#15 a__l

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Posted 04 July 2020 - 07:19 AM

https://www.fujifilm...a-Pixel 1.0.pdf

 

Relative illumination (aperture at full open) image height at diagonal  34



#16 GrahamDFyffe

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Posted 04 July 2020 - 02:04 PM

https://www.fujifilm...a-Pixel 1.0.pdf

 

Relative illumination (aperture at full open) image height at diagonal  34

so in theory yes it will fully illuminate the sensor? It also seems to have an M49 thread. Does someone make an M48 to M49 adapter so you could use 2" filters?



#17 john hraba

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Posted 04 July 2020 - 02:21 PM

Let me know how the CF16HA works out. I too am looking for a short focal length objective that will fully illuminate the sensor.

The CFHA16HA-1 lens is designed for a 1" format.  A 1" format lens has a diagonal of 16mm; the photocathode of my MOD3-C has a diameter of 18mm.  So I shall see how well it works in practice.  Frankly I expect it to work well enough for my experiment.  While a 4/3 format lens would be corrected over the entire sensors diameter, actually 22mm, it would be much larger, heavier and more costly.  You may find following the link to the Thor Labs Camera Lens Tutorial of interest:  https://www.thorlabs...ctgroup_id=1822

so in theory yes it will fully illuminate the sensor? It also seems to have an M49 thread. Does someone make an M48 to M49 adapter so you could use 2" filters?

A 48mm to 48mm step-down ring is available from B&H and ebay.  My plan is to use my 2" long pass filters.



#18 a__l

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Posted 04 July 2020 - 06:59 PM

so in theory yes it will fully illuminate the sensor? It also seems to have an M49 thread. Does someone make an M48 to M49 adapter so you could use 2" filters?

For my CF75HA-1, I bought on AliExpress RISE (UK). There are so many different rings for threads of different diameters.
I use 2" Baader H-Alfa 7nm and 685 nm filters. This filters have threads on both sides. I use an additional light shield.

 

I liked this Fujinon. In addition, it is much easier to adapt to NV than the Zeiss Jena DDR Tevidon 25mm f/1.4 (4/3 standard). I spent a lot of time installing Zeiss on NV.
Now I am pleased with both lenses.


Edited by a__l, 04 July 2020 - 07:10 PM.


#19 john hraba

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Posted 23 July 2020 - 03:44 PM

In post #13, of this thread, I mentioned ordering a Fujinon CF16HA-1 which is a 16mm focal length, 1” format, c-mount lens sold for machine vision.  I received the lens and have had a chance to use it.  So I thought I would share my findings.  I believe most of what I learned would apply to the other focal lengths in the CF-HA series shown here and here

 

My conclusion is, while not perfect, I am planing to keep the lens.  What I like about the lens is the field of view covered by the lens is about 65 degrees which is shown in the 40 degree field of view of the eyepiece of my MOD3-C, see photo of Big Dipper below.  The field covered has about 2.8 times the area that would be visible in an Envis lens.  Wide open at f/1.4 the central region is quite sharp with the edge being a bit soft, certainly usable for spotting meteors. By f/2.8 the lens is relatively sharp over the entire field of the MOD3-C. 

Since the lens is only designed to cover a 1” diagonal format, which has a 16mm diagonal, it was gratifying to see that the lens’ performance was still reasonable over the full 18mm field of the MOD3-C sensor.  The lens’ distortion is not apparent by eye, the specs claim 0.96% total distortion, which seems believable.

 

A few points of concern if considering one of the lenses of this series specific to mounting on a MOD3-C.  The diameter of the lens at it’s base is 50mm; where it attaches to the MOD3-C.  What this means in practical terms is that the gain knob of the MOD3-C must be nearly flush with or below the plane of the c-mount flange or the lens will not mount, see photo below.  If you try adding a 5mm spacer to the rear of the lens, the lens will mount but will not reach infinity focus.  It turns out, with my device I had to shim the lens 1mm forward to get the lens to focus near where it should in it’s focusing range.  The shims are visible, in yellow, in the photo below.  This was probably due to my not having the o-ring in place.  Just mounting the lens without the shim resulted in the lens focusing about 1/3 of the way through it’s travel and an increase in edge darkening.  The photo below of the big dipper shows the lens’ edge darkening which the spec’s lists as 35% relative illumination at the edge, perhaps a bit less since the value given is for a 16mm diagonal and the photo is showing the field at 18mm.  The edge darkening decreases as the lens is stopped down.

 

The lens has a 49mm front thread.  I tried mounting a 2” diameter filter using a 49mm to 48mm step-down ring to this thread.  The result was vignetting.  Or put another way the edge darkening increased in the last 10% of the field of view.  Still usable but for meteors probably better without the filter.

 

IMG_0232.jpeg

 

The photo of the Big Dipper, below, was taken with the lens on my MOD-3C using an iPhone XR with NightCap ISO 24, 1/3 second shutter speed, averaged for 10 seconds.

 

IMG_0091.jpeg

 

 


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#20 a__l

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Posted 23 July 2020 - 08:30 PM

I believe most of what I learned would apply to the other focal lengths in the CF-HA series shown here and here

 

I think that this is not entirely true. 75 and 50mm stand-alone f/1.8

 

Wide open at f/1.4 the central region is quite sharp with the edge being a bit soft, certainly usable for spotting meteors. 

What users write in the review, you must match the position in the lens adjustment at infinity (or close) and a sharp image on the tube. Otherwise, the picture becomes softer around the edge. Although it may have something to do with my next comment.

 

Just mounting the lens without the shim resulted in the lens focusing about 1/3 of the way through it’s travel and an increase in edge darkening.  The photo below of the big dipper shows the lens’ edge darkening which the spec’s lists as 35% relative illumination at the edge, perhaps a bit less since the value given is for a 16mm diagonal and the photo is showing the field at 18mm.  The edge darkening decreases as the lens is stopped down.

Likewise. The closer the lens (glass) is to the tube (more precisely to the out hole), the less vignetting. In my case, there are additional option. I can cut the right side of the threaded bronze c-mount adapter to a minimum. Photo. In order to further reduce vignetting. Whether this makes sense, we'll see later.

 

The lens has a 49mm front thread.  I tried mounting a 2” diameter filter using a 49mm to 48mm step-down ring to this thread.  The result was vignetting.  Or put another way the edge darkening increased in the last 10% of the field of view.  Still usable but for meteors probably better without the filter.

This is not the case for 75 mm. I don't see vignetting using 2" filters.

In any case, I am moving in the direction of decreasing the focal length of the lens and my next step will be CF25 mm (package on the way).

 

Should not be concerned about the shine of the internal thread of the adapter. In any case, Televue doesn't care.

Attached Thumbnails

  • CF75_C-mount_.jpg
  • N31_.jpg

Edited by a__l, 24 July 2020 - 12:17 AM.


#21 cnoct

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Posted 23 July 2020 - 10:02 PM

Very nice set up john hraba, looks a bit like a spaceship! salute.gif

 

In post #13, of this thread, I mentioned ordering a Fujinon CF16HA-1 which is a 16mm focal length, 1” format, c-mount lens sold for machine vision.  I received the lens and have had a chance to use it.  So I thought I would share my findings.  I believe most of what I learned would apply to the other focal lengths in the CF-HA series shown here and here

 

My conclusion is, while not perfect, I am planing to keep the lens.  What I like about the lens is the field of view covered by the lens is about 65 degrees which is shown in the 40 degree field of view of the eyepiece of my MOD3-C, see photo of Big Dipper below.  The field covered has about 2.8 times the area that would be visible in an Envis lens.  Wide open at f/1.4 the central region is quite sharp with the edge being a bit soft, certainly usable for spotting meteors. By f/2.8 the lens is relatively sharp over the entire field of the MOD3-C. 

Since the lens is only designed to cover a 1” diagonal format, which has a 16mm diagonal, it was gratifying to see that the lens’ performance was still reasonable over the full 18mm field of the MOD3-C sensor.  The lens’ distortion is not apparent by eye, the specs claim 0.96% total distortion, which seems believable.

 

 

attachicon.gifIMG_0232.jpeg

 

 

 



#22 a__l

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Posted 24 July 2020 - 12:08 AM

By the way, I looked at the diameter of the image in the focal plane for the CF75, it is more than 23 mm. The tube will have a cropped image.



#23 GrahamDFyffe

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Posted 24 July 2020 - 12:52 AM

So is there a reason you did not go down to the 12.5mm? Seems like that would give you an even wider view albeit at cost of pretty low magnification (ok reduction). Might be interesting afocal with say a Baader Morpheus 17.5mm 76° eyepiece.



#24 SiriusLooker

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Posted 24 July 2020 - 11:37 AM

A side note also is the (after math) of a bright streaker. That can be just as impressive to see, and in some cases for a minute or more later,-- the very detail smoke trail left behind is remarkable in NV.. Having the look of Veil nebula on a large scale. Those few that I have seen are still implanted in my feeble mind of the NV.. I too have recently acquire multiple ultra wide lens just for this purpose, to view meteor showers and the like.--having 10mm Zeiss, 12mm Zeiss, 16mm,. I have been pushing my NV. lately to its upper most (flexible limit), and hope to present that very soon here. For the record, being very fortunate, the brightest Meteor I have seen in over 50yrs, gracing over 3/4quarters of the sky, seen over multiple states, and still quite vivid in my mind, -- happens to be on film!.

Forgot to give location-(Fireball-Photo)-March 2002 Astronomy Magazine, Pg 103. Article by me too.



#25 john hraba

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Posted 24 July 2020 - 03:17 PM

So is there a reason you did not go down to the 12.5mm? Seems like that would give you an even wider view albeit at cost of pretty low magnification (ok reduction). Might be interesting afocal with say a Baader Morpheus 17.5mm 76° eyepiece.

The reason I did not go to a shorter focal length lens was because of my concern that objects, like constellations, would be so small that they would be insignificant visually.  I thought the step to 16mm would be reasonable to still allow a pleasing image since I mainly plan to use this lens visually.  From what I have seen so far I am pleased with the choice.  Perhaps after using the 16mm lens for a time I may decide to try a shorter focal length.  If I were attaching the lens to a camera to do a meteor survey a shorter focal length might be a better choice.




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