One example based on P8079Hp for long range night spotter...

Show and tell for your homebrew nv projects. DIY 'Stickies' here too.
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Lambda
Posts: 21
Joined: 31 Oct 2017, 17:41
Location: Den Haag, NL

One example based on P8079Hp for long range night spotter...

Post by Lambda » 31 Mar 2018, 21:38

Hello,
Following the topic of diy project base on a watec 120n+,

viewtopic.php?f=29&t=18536

Here is presented an illustration about what is doable on a « kitchen table corner » with old mil surplus tube (the famous British P8079HP), pvc tubes, and as usual epoxy/duct tape.... the tube being fed by a old Russian catadioptric lens I slightly modified for rendering it a bit faster (originally f/10, f=1000mm, now around f/7, f=700 mm). Eyepiece being a 30 mm focal length 2 ‘’ barell, initially designed for astronomical purpose). Magnification of the system ( conventional direct visual using), around X20.
nv tube is optically coupled to the sensor of a Sony dschx1 bridge in afocal fashion. Purely passive, no IR.

Here some shots and video... sorry for low quality, I did crude records from the screen of the bridge... next week I should be able to post here the mpeg and jpeg files coming from the memory card of the bridge...

It gives just for now some glimpse of the system.

The main idea is to, in a close future, replace the bridge by a high def cctv cam having sense up and adjustable gain and À gamma correction, in order to increase the SNR ratio of the whole system. Which is not yet the case with the limited video possibilities of the Sony dschx1 (but for photos, with adjustable exposure time, it works greatly...)

Here is the video... the source file quality is better, definitively

https://youtu.be/_2khzABlwkE

Here is some shoots, photo mode. 1/4 sec exposure, 125 iso

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The church is more than one km from me, see the previously cited post for environmental details, around full moon but fully overcast when video and photos made...

Hoping it can bring some elements for the night owl community here.

Thank you.

Regards.

Lambda

hatti
Posts: 34
Joined: 14 Feb 2014, 17:32
Location: Riga

Re: One example based on P8079Hp for long range night spotter...

Post by hatti » 10 Apr 2018, 17:15

amazing - so little noise at f/7 :o

thank you for detailed report - you are giving me ideas.

i have some tubes to do fun stuff with.
maybe someday i will try to bond some sensor directly to the fiber optic plate.

unfortunately p0879hp has some sort of protective plastic window over the FO output.
i don't know whether it can be removed easily without tearing off elastomer of the rear end of tube.

good luck and keep posting!

Lambda
Posts: 21
Joined: 31 Oct 2017, 17:41
Location: Den Haag, NL

Re: One example based on P8079Hp for long range night spotter...

Post by Lambda » 10 Apr 2018, 22:54

Hello.

Thank you Hatti for your encouragements.

Yes, by combining a sensor working with long time exposure or in stacking/sensing up mode, we increase in a sensitive mannner the SNR of the whole dispositive, rendering therefore the perception of the grain of the picture, when use with slow optics and/or in too low light condition, less visible.

Already with the native settling of the video mode of my bridge, it is perceptible... but with long time exposure (here 1/4 s) for shots, it is really remarquable.

The idea of my project is to equip the tube with a video camera allowing to freely adjust rate frame, and therefore time exposure by sensing up to benefit the best of the two worlds: reasonable vidéo fluidity and improved SNR with sensitivity brought by the tube.

In normal using, with naked eye and this f/7 optics, the picture is normally darker, grainy, but nevertheless still surprisingly quite sharp in term of definition.

For the direct coupling, by using a tapered optic fiber plate, it would be generally speaking the best solution... time to time on eBay such plate can be found, or also available by Edmund optics company, for instance or Thorlab... but requiring a large budget and having to be selected and sized for matching the size oh the sensor used: a demagnification ratio has to be defined and respected.... a direct coupling sensor/FO of the tube would be also doable, but at the cost of the FOV which would be very small ( by not using the full surface of the FO screen: no demagnification ration... and also less coupling efficiency).

But as you rightly mentioned, the screen if the P8079HP is unfortunately not a pure erected FO ... this additional protective window sucks, for applying this solution.... perhaps the focus mismatch -induced by this window preventing access to the right focal plan on the FO - would be perhaps acceptable?? No idea... it would depend also on the resolution of the sensor, I guess: if low/coarse resolution perhaps this mismatch would be un-noticeable?

But practically, the solution of the relay lens is still the more accessible for us as hobbyist, and is giving good result in term of resolution and the intrinsic low coupling efficiency of this solution can be easily compensated by the sensing up method applied with the sensor. And also trying to have the best lenses as possible for creating the relay lens itself.

Nevertheless, according your hunting activity, only a sensing up X2 to max X4 (depending on the time exposure of the unitary vidéo frame) would be acceptable, I guess. But still interesting by also playing with gain and gamma correction...

At the end, nothing new under the stars... just that today, tech and access to the tech have evolved sufficiently to allow us, as individuals/hobbyists, to develop and implement the « old » ICCD concept and system, which were only available 20 years ago, for univ labs/r&d dpartment of wealthy company/gov/mil...

For this project of long range spotter, I ordered one tft screen 5 ‘’ (480X800) to sure24 and will soon order a model of KPC camera from them suitable for my purpose. The relay lens will be made of the current eyepiece (2’’ Barrel, f=30 mm, f/0.8) and à Computar lens (f=6 mm, f/0.8), mounted in afocal manner, in vis a vis. The demagnification obtained here (x0.2) should allow the sensor of the camera (1/3 ‘’) to be roughly more or less properly covered by the 25 mm diameter of the Screen of the P8079HP (i think that the sensor of the cam will be slightly, in one dimension, overfilled by the image circle of the image provided by the tube screen...).

Here is the status of my project... sorry for the length of my disclosure... hoping not boring the community here.... :oops:
Hoping also to bring, humbly, some general ideas helping you to develop your own projects...

Hatti, please, I would be very curious, and also enthusiastic, to see your own tries with your tubes, in this sense...

Thank you all for your reading patience.

Best regards.

Lambda

hatti
Posts: 34
Joined: 14 Feb 2014, 17:32
Location: Riga

Re: One example based on P8079Hp for long range night spotter...

Post by hatti » 19 Apr 2018, 10:34

so far i have built only a few simple "objective > i2t > ocular" thingies.

cascade and gen2 mx9644 rifle scopes
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mx10160 head mounted binocs (not quite finished,but functional)
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now i am trying to build a 6 inch f/8 achromat refractor readily compatible with cascade scope
here is picture of focuser with scope attached.
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Lambda
Posts: 21
Joined: 31 Oct 2017, 17:41
Location: Den Haag, NL

Re: One example based on P8079Hp for long range night spotter...

Post by Lambda » 19 Apr 2018, 19:01

:shock: :clap: :clap:

Hatti, What a beautiful bunch of réalisation you have done there! Impressive, really.... masterizing a metal lathe is something you seem to do well!

Did you have the occasion to compare, with the same objective, performances of your cascade tube and your gen 2 mx 9644? In terms of contrast, brightness and visual resolution?

Here, for this project, I finally cannibalized the other watec 120n+ Project, in order to complete this one... because this watec model offers a very flexible and wide range of adjustment particularly suitable for this iccd project.

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It is more or less the final version of this « prototype « ... what can just be changed is to replace my crappy battery pack by something more compact and with bigger capacity.

The green board magnet is used for maintaining open the iris of the Computar objectif which is the second part of the relay lens. Indeed, normally, the iris is maintained opened thanks to an electrical signal provided by the camera itself. But such way consumes a lot of energy and exhausts quickly batteries. With the board magnet properly positioned and glued on the body of the objective (empiric trials) it is possible to maintain it permanently open, without using juice...

With a sense up settled at X2, and gain at minimum, playing with the gamma correction, results are really impressive.... better than my other gen 3 project, in term of contrast and brightness of the image, but with a bit lower resolution in term of visual feeling... I can really obtain an image having the amount of information provided by a « long exposure « photo, as shown in
Above posts of this thread (photo of the church), at least equivalent or even superior, but in true or quasi true video mode.

Here is my other mx10160 monocular fed with a f/1, 90 mm lens. Definitively more portable than the iccd project.

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The next project will be based on making a binocular night spotter using a f/0.75, f=50 mm lens feeding a watec 910hx with a lcd viewfinder adapted on an optical binocular head, if possible... but first à budget has to be build... :D


Best regards.

Lambda

hatti
Posts: 34
Joined: 14 Feb 2014, 17:32
Location: Riga

Re: One example based on P8079Hp for long range night spotter...

Post by hatti » 19 Apr 2018, 20:06

yeah,that cascade tube and sensitive camera combo clearly has huge potential!
a real improvement over bare tube.

as for cascade vs mx9644,i did comparison pictures a couple years ago.

both scopes had 75mm f1.1 object lenses, same scene, same illumination level - moonless overcast night.
no light pollution.

mx 9644 minimal gain
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mx 9644 maximal gain
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cascade
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Lambda
Posts: 21
Joined: 31 Oct 2017, 17:41
Location: Den Haag, NL

Re: One example based on P8079Hp for long range night spotter...

Post by Lambda » 20 Apr 2018, 09:13

Thank you Hatti for these photos.

The cascade tube is definitively impressive, compared to the more recent gen 2 like the MX9644:

Better contrast/SNR, resolution, brightness.... just these typical geometrical pin cushion distortion, but which is quite small and really not disturbing (for me).

One additional evidence of the non systematic pertinence of gen classification system for estimating true performance of a nv tube.

Regards,

Lambda

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some bloke
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Re: One example based on P8079Hp for long range night spotter...

Post by some bloke » 20 Apr 2018, 10:15

Blimey - someone else used wood too. :lol:
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