What really is EEVA

[saac]

2 minutes ago, vlaiv said:

Regardless of how we name things - I just had my first night vision session (EEVA style ) to prove above concept works.

Details:

- target is TV tower about 6.5 miles away

- scope used is 32mm F/4 finder/guider by Astro Essentials

- primary focus eyepiece - 17mm plossl giving magnification of about x7.5

- NV device - Xiaomi A1 with full HD display and 400ppi screen resolution

- observing eyepiece 32mm plossl - field stop about 27mm - FOV resolution about 425 points on diagonal (this needs to be as high as possible for smooth display - it is number of visible "pixels" on diagonal of AFOV).

Mind you - this is hand held setup so everything was rather shaky and not properly spaced / aligned

Anyway - here is image at observing eyepiece snapped with Canon 750D (don't ask how I managed to hold phone, eyepiece and camera together to do this )

You can actually see some screen around the eyepiece since camera was moving and I snapped the image as it was further away from the exit pupil - not whole eyepiece FOV is visible here and image is zoomed in comparison to what you see at eyepiece (and yes, I did look and you can see the pixels regardless the fact that it is not as zoomed in).

I also managed to snap image (well touch screen did as I accidentally pressed it while holding the eyepiece against the screen):

So above is what phone camera sees at the prime focus eyepiece (17mm one).

If you want to try this - remember to unscrew 1.25" barrel from the observing eyepiece as field stop needs to almost touch the phone screen (phone screen needs to be at focal plane of observing eyepiece).

Nice experiment . Do you know of any stacking app that runs on mobile phone?

Jim 

[PeterW]

.... the resolution means stars aren’t probably quite as tiny pointy as with glass... though binocular glass views give better stars as your brain can average... and binocular NV views enable even fainter nebulosity to be seen. 
So many ways to enjoy the sky and see stuff, so many things to look at....

Where I (sometimes) differ from @GavStar is that I have usually done NV handheld, giving me freedom to scan and view where I want... less “artificial” than pushing buttons and letting Goto take you to specific locations. 
 

I’d quite like to see what the Sony A7 with a wide fast lens could offer and I wouldn’t mind looking through a sionyx digital system, though even it lacks the sensitivity for nebulae.
 

Peter

[vlaiv]

1 minute ago, saac said:

Nice experiment . Do you know of any stacking app that runs on mobile phone?

Jim 

Actually I don't but for the time being I would settle for setup that I don't have to hold so it does not fall apart and simple application that will cycle half second exposures on screen or even 33ms ones - like live video with photon noise and all - just to see if it will be anything like nv experience.

I would also like eyepiece with larger field stop - like simple 55mm plossl. That would double number of points on diagonal which would make smoother appearance.

There seems to be an issue with mobile phones - well, at least android ones. Google included very nice feature in android OS back in 2015 - called Camera2API which enables software developers to fully use camera hardware - which means raw data and all. However it seems that phone manufacturers exploited this in ways not intended by Google - they only enable it on their flagship models as selling/marketing trick (better camera capabilities).

If it proves to work then I guess 3D printed parts to hold everything together and phone app will be eventually developed, right?

[PeterW]

For experience (though in old fashioned green) you could do worse that listening to JDB...

I agree, it’s the experience we’re after, some people get blown away by seeing Saturn’s rings or the odd moon crater to two, some seek more.... let’s hope for some clear skies we can actually use in ‘21....

Peter
 

[Moonshed]

Have to say vlaiv I am impressed with your image but even more with your ingenuity.

[vlaiv]

Resolution of this system is quite nice visually if one manages to put more than 1000 points per diagonal. I did try it on number of occasions - I even have M51 image in my phone that I observed

However, in order to do that with 32mm finder - I need to keep phone more than arms length away from scope + eyepiece. I don't know what sort of optic arrangement would be needed to bring that down in length.

Here is diagram for that arrangement - and I think it would work nicely - since I tried two separate halves of it and it works:

So I tried putting phone against telescope - and as you've seen in image above, it works nicely.

I also tried looking at the phone with finder / eyepiece combo. It has all the advantages and only one disadvantage - it needs distance to work properly. Say we use 32mm F/4 finder and 17mm eyepiece as device to observe the phone (this is really done so that one has "eyepiece" experience - otherwise they might just look at phone screen - but we want to do the same as NV devices here) then we need to place phone at following distance from finder:

If we have 7cm to be width of phone display and we have x7.5 magnification and we have lens formula like 1/f = 1/a + 1/a*7.5 => 1/f = 8.5 / 7.5*a => 8.5*f = 7.5*a => a = 8.5/7.5 * 128mm = 145mm

Distance is 7.5 * 145 = 1088mm = over 1 meter away.

I managed to mess up above calculation. We don't need to use x7.5 magnification of the system at infinity but rather ratio of phone screen width and field stop of 17mm plossl eyepiece in this calculation. Field stop should be around 14.3mm so magnification used should be 70mm : 14.3mm = ~x4.92

1/f = 1/a + 1/a*4.92 => 1/f = 5.92 / 4.92 * a => a = 128mm * 5.92 / 4.92 = 154mm

Distance is 4.92 * 154mm = 757mm = 75.7cm - that is more arms length

 

Edited December 24, 2020 by vlaiv

[Macavity]

Without my "Watec Revelation", I doubt I would have got back into Astronomy?
Sadly, dreams of smaller pixels, 16-bit real-time integration, proved just that. 😛

But then, technology had to rely on "popular demands" (e.g. security Cams)?
TBH, I felt the (strictly) no post processing rule rather "nailed the coffin" too... 😐

I started at wrong time? lol. Just before offline integration came to dominate. 🥳
But 8-bit stacking (stacks) was a fun challenge. I may yet reprocess some of it...

[saac]

54 minutes ago, vlaiv said:

 

If it proves to work then I guess 3D printed parts to hold everything together and phone app will be eventually developed, right?

That's just what I was thinking vlaiv, maybe a Christmas break project   

Jim 

[Scooot]

1 hour ago, saac said:

Nice experiment . Do you know of any stacking app that runs on mobile phone?

Jim 

You can do live stacking with the ASIAIR Pro and use the Asiair app on the phone or tablet to view it if that counts.

[vlaiv]

8 minutes ago, Scooot said:

You can do live stacking with the ASIAIR Pro and use the Asiair app on the phone or tablet to view it if that counts.

In another thread, not long ago, I  mentioned possibility of having ASCOM / INDI drivers for phone camera.

It would work over the network and you would install one application on the phone that would snap images and transmit them to the other app installed on the lap top which would in turn present itself via ASCOM or INDI as camera interface.

That way you could use applications like SharpCap or OACapture to do live viewing / stacking at your computer.

By far the cheapest solution for EEVA - most if not all have phone with decent enough camera and adapters for them to be attached to the telescope + eyepiece are rather cheap. Rest is software support.

This approach offers a lot of flexibility.

- Phone could be used attached to telescope to do EEVA in the field without any additional devices. Image would be presented on telephone screen

- Phone could be used as electronic eyepiece that would stream images to laptop / tablet via wifi

- Phone could be used as integral part of night vision device with addition of another eyepiece or some sort of optical assembly.

In principle one application for phone could handle all these tasks.

[nicoscy]

Sigh, being admin on CN means that I had to go through recurring bouts of trying to define EAA / EEVA / NV. These were the great EAA wars on CN. What came out of it:

EAA is viewing without an eyepiece, doing any enhancements available in real time and while one is observing (applying calibration frames real time, tweaking software display options, cooling etc). Anything done to the actual image after observing (post processing) is considered imaging. As an avid EAA practitioner, this is how I see EAA. I do both traditional viewing and EAA viewing and I consider them complementary and I also consider myself lucky to have options available.

NV is traditional viewing with an eyepiece, but that eyepiece offers on the fly enhancements. There are no laptops involved, no ASIAir Pros (love mine), no external power packs, no cables, no CMOS or CCD cameras, nothing else except slotting your electronic eyepiece, or doing afocal NV and immediately just observe. It is different enough to EAA to deserve its own classification, as the equipment used is wildly different and techniques used are wildly different.

Feel free to ignore my opinion of course, but I do wonder why so much energy is devoted to define how one observes. There are a host of different opinions, but in the end, as this is a privately owned forum, the admins will decide the direction they wish this place to follow.

I would vote, if a vote was asked for, for a separate NV forum. Why? Observations are conducted differently, equipment discussions are completely different and the end result is quite different too. My 2c

[vlaiv]

3 hours ago, nicoscy said:

There are no laptops involved, no ASIAir Pros (love mine), no external power packs, no cables, no CMOS or CCD cameras, nothing else except slotting your electronic eyepiece, or doing afocal NV and immediately just observe. It is different enough to EAA to deserve its own classification, as the equipment used is wildly different and techniques used are wildly different.

But is it really?

Have you seen this device:

https://www.omegon.eu/digital-night-vision-device/omegon-alpheon-nv-5x40-night-vision-device/p,47286#tab_bar_0_select

Here is a quote from description:

Quote

The generous internal memory allows you to take more than 7,000 photos or record multiple, up to 10 minute, video sequences. The USB interface and AV output let you output these images to a PC or TV to share them with friends.

and resolution is quoted to be 640x480 ...

Best night vision device is not one with photo multiplying tube - but rather just the above - good sensor with high QE over the whole spectrum and into IR. High density display with high contrast ratio and clever software in between.

I would not be surprised that 3/4 gen devices use the same approach. I read once that there is bloom suppression in one such device - and I can't help notice that is easily done in software.

In the end - it is just how one optimizes the size and everything is already small enough to pack into eyepiece sized package, but it is still - sensor and display and computer and some optics to make it work nicely together.

[PeterW]

No. The ONLY digital NV device that gets within a mile of Gen3 intensifiers is the Sionyx (with its special black coating and HUGE pixels). Even it has trouble when things get dark... like when you want to look at nebulae. I am sure it mig he be possible to do better.... the phone machine learning approaches can do wonders with pictures in conditions no sane photographer would normally expect anything..... if there is a market and money to do the development. But no few hundred )£/€/$/¥ digital device will disappoint.

Peter

[vlaiv]

10 minutes ago, PeterW said:

But no few hundred )£/€/$/¥ digital device will disappoint.

I'm sure they will - but I was just making a point that whole system can be packaged into eyepiece sized device.

Don't really follow how intensifier can perform better when both devices operate on the same input. No device can produce more light than there already is.

In fact - intensifiers don't do longer exposures, right? I mean standard ones - based on photo multipliers. That is why there is so much photon noise in intensified image as each photon is represented as a small flash of light. Would we loose anything by doing 30ms exposure?

I guess in wartime conditions - yes, you want the best interaction with environment as possible - but for astronomy? I don't think most people would mind even 100-200ms exposures, it would still be considered real time.

[nicoscy]

14 minutes ago, vlaiv said:

But is it really?

Have you seen this device:

https://www.omegon.eu/digital-night-vision-device/omegon-alpheon-nv-5x40-night-vision-device/p,47286#tab_bar_0_select

Here is a quote from description:

and resolution is quoted to be 640x480 ...

Best night vision device is not one with photo multiplying tube - but rather just the above - good sensor with high QE over the whole spectrum and into IR. High density display with high contrast ratio and clever software in between.

I would not be surprised that 3/4 gen devices use the same approach. I read once that there is bloom suppression in one such device - and I can't help notice that is easily done in software.

In the end - it is just how one optimizes the size and everything is already small enough to pack into eyepiece sized package, but it is still - sensor and display and computer and some optics to make it work nicely together.

NV devices as they are used, do not by themselves stack images. Rather, they enhance in real time. Sure, you have phonetography for NV, but that is just to convey what is seen and it is not the means by which NV is practiced.

Traditional EAA is either say one very long image where photons are stacked over time, or some short images which are stacked. "Traditional" EAA is near real time. NV is real time.

Disclosure: I only do "traditional" EAA. My stacks are in the order of 10 seconds of anything between 10 to 20 frames. Yes, I have a "usable" image to observe in 20 seconds and then it just improves with more stacking. But NV - it is instant, at the eyepiece.

I guess that is the separator - for the time being with current technology - that NV is real time  - 0-100miles in a fraction of a second real time - electronic enhancement at the scope with an eyepiece that includes all electronics Vs traditional EAA which is near real time but not quite there, and employs much additional gear.

[PeterW]

Intensifiers have noticably lower quantum efficiency and no ability to add clever electronics.... so should be worse. Long exposures statistically average the random photon arrivals and show the fainter detail. 200ms exposure will give 5Hz refresh, which from my thermal experiences is poor unles you have a stable(possibly tracking) mount. >30Hz is much preferred for moving scenes.

 

Peter

[nicoscy]

1 minute ago, vlaiv said:

I'm sure they will - but I was just making a point that whole system can be packaged into eyepiece sized device.

Don't really follow how intensifier can perform better when both devices operate on the same input. No device can produce more light than there already is.

In fact - intensifiers don't do longer exposures, right? I mean standard ones - based on photo multipliers. That is why there is so much photon noise in intensified image as each photon is represented as a small flash of light. Would we loose anything by doing 30ms exposure?

I guess in wartime conditions - yes, you want the best interaction with environment as possible - but for astronomy? I don't think most people would mind even 100-200ms exposures, it would still be considered real time.

 

A 219 euro device is no competition for modern white phosphorus devices costing at least 30x more for the bare minimum. Now, if your aim is to see some wild life at night and at relative close proximity, this device (the Omegon) will do. It works with an infrared illuminator, so quite different to the devices used for NV...

[PeterW]

.....if you are looking to go wildlife spotting then thermal is a much better bet, monochrome visible light kit (intensifier/digital etc) doesn’t make alive (warm) things so immediately visible.

the sionyx or a secondhand Gen 3 would be a good complement for going walkies at night without bumping into things or advertising your presence with a glowing red “eye”.

For EEVA you want a tracking mount and a low cost astro ccd/cmos camera or a fast scope and a Gen3 intensifier. 

 

Peter

[vlaiv]

3 minutes ago, PeterW said:

For EEVA you want a tracking mount and a low cost astro ccd/cmos camera or a fast scope and a Gen3 intensifier. 

Or combination.

I need to test out another option for EEVA that will be hybrid approach of these two and could possibly allow for real time observing without stacking (or combination there of - switch stack on/off).

Optically it would be the same as NV device but in operation it would be same as EAA approach.

Take a scope, put an eyepiece in it. Take a camera and put a lens on it. Now stick two together

Main issue with cheap astro cameras is small sensor and if you do prime focus EAA - you have relatively small FOV. This also means that for the most part you have rather high sampling rate - which dilutes light over many pixels.

If properly matched, above approach can create wide field with low sampling rate - lot's of light per pixel.

Say you take 4" F/5 refractor (If you want apo performance - use 4" F/7 doublet and reducer / flattener). Stick 32mm plossl in it. This will give you something like 3.33° of FOV translated into 50° AFOV. Take ASI224 and 6mm C/CS-mount lens. At this crop factor 1/3" sensor gives 53° on diagonal with 6mm lens.

It will capture whole field of 50-52° plossl.

Such a fast system will have a bit of field stop so you can actually use something slower. Exit pupil will be around 6mm, but most 6mm lenses are as fast as F/1.2 so only 4mm entrance pupil. I don't think one could easily get F/1 6mm lens - so this needs to be taken into consideration when putting together a setup.

Another option is to use slightly larger sensor - for example ASI178 which needs 12mm lens to image 50° FOV. 12mm lens will be able to get whole 6mm exit pupil even at F/2.

[bomberbaz]

Ever wished you hadn't asked that question? 🤣

[Highburymark]

On 28/12/2020 at 07:45, nicoscy said:

Sigh, being admin on CN means that I had to go through recurring bouts of trying to define EAA / EEVA / NV. These were the great EAA wars on CN. What came out of it:

EAA is viewing without an eyepiece, doing any enhancements available in real time and while one is observing (applying calibration frames real time, tweaking software display options, cooling etc). Anything done to the actual image after observing (post processing) is considered imaging. As an avid EAA practitioner, this is how I see EAA. I do both traditional viewing and EAA viewing and I consider them complementary and I also consider myself lucky to have options available.

NV is traditional viewing with an eyepiece, but that eyepiece offers on the fly enhancements. There are no laptops involved, no ASIAir Pros (love mine), no external power packs, no cables, no CMOS or CCD cameras, nothing else except slotting your electronic eyepiece, or doing afocal NV and immediately just observe. It is different enough to EAA to deserve its own classification, as the equipment used is wildly different and techniques used are wildly different.

Feel free to ignore my opinion of course, but I do wonder why so much energy is devoted to define how one observes. There are a host of different opinions, but in the end, as this is a privately owned forum, the admins will decide the direction they wish this place to follow.

I would vote, if a vote was asked for, for a separate NV forum. Why? Observations are conducted differently, equipment discussions are completely different and the end result is quite different too. My 2c

Agree with all of this. Except we don’t have enough NV practitioners on SGL to justify a separate forum at the moment. Trouble is we have almost nothing in common with EEVA either. The only threads we can all contribute to are these long discussions trying to define what EEVA is. There’s no common ground - unless we use the same filters. 

 

[nicoscy]

5 minutes ago, Highburymark said:

Agree with all of this. Except we don’t have enough NV practitioners on SGL to justify a separate forum at the moment. Trouble is we have almost nothing in common with EEVA either. The only threads we can all contribute to are these long discussions trying to define what EEVA is. There’s no common ground - unless we use the same filters. 

 

Agreed and noted. On CN we had to reach a critical volume of both topics / posts and number of active members before taking action...

How about using tags for NV related topics?

[vlaiv]

4 minutes ago, Highburymark said:

Trouble is we have almost nothing in common with EEVA either.

Lines are getting blurrier every day.

Many people getting into astronomy come with idea that they want to do it all - they want to observe but also to snap a few pictures, maybe record a video. They often live in big cities with lots of light pollution.

One solution to above equation is visual setup capable of EEVA on some level, maybe just smart phone connected to eyepiece.

Once people get into astronomy without preconditioning (I'm visual astronomer or I'm imager, or I doing NV), they will be quite open to all styles and won't even think that there is "strong" distinction.

For their benefit it would be nice to have place to discuss it all.

[PeterW]

I am very happy to discuss and very keen for people to go try stuff out, don’t just do what others have before, that’s how we discover new and better ways of doing things... watec to short exposure ccd and NV... a “smartphone” type approach may well be round the corner, bringing down the cost and complexity of EEVA, but it’s got to deliver the goods. Seems that EEVA and NV observers don’t often look at the same objects, NV preferring wider field objects.

PEter

[GavStar]

2 hours ago, Highburymark said:

Agree with all of this. Except we don’t have enough NV practitioners on SGL to justify a separate forum at the moment. Trouble is we have almost nothing in common with EEVA either. The only threads we can all contribute to are these long discussions trying to define what EEVA is. There’s no common ground - unless we use the same filters. 

 

I think some night vision discussion on sgl even with the existing few practioners on a separate nv forum would be better than the current virtual zero nv discussion that happens on the eeva forums. A separate forum might also prompt more people to consider trying nv.

Edited December 29, 2020 by GavStar