39 replies to this topic

[AllStarez]

Gavin,

 

by any chance, have you got some more photos to share using your Askar ? 

[Gavster]

Gavin,

 

by any chance, have you got some more photos to share using your Askar ? 

Unfortunately it’s likely to be a few weeks before I can but will try to get some done at a dark site.

[AllStarez]

I have received mine and it works just fine

tried it with the TS filter changer, the good news is it could reach focus 

 

[trias702]

Does anyone happen to know what sort of housing the OVNI-M uses? I know the OVNI-B is a vanilla PVS-7, but am not sure about the OVNI-M. I think it might be a PVS-18?

[Joko]

Does anyone happen to know what sort of housing the OVNI-M uses? I know the OVNI-B is a vanilla PVS-7, but am not sure about the OVNI-M. I think it might be a PVS-18?

OVNI-M housing is... from OVNI-M housing.

While OVNI-B is made with some PVS-7 parts but there are a lot of differences.

[trias702]

OVNI-M housing is... from OVNI-M housing.

While OVNI-B is made with some PVS-7 parts but there are a lot of differences.

If I may please ask, what are the differences for OVNI-B vs vanilla PVS-7?

 

Also, does the OVNI-M housing use the same MX10130 tubes as the OVNI-B?

Edited by trias702, 03 December 2021 - 11:06 AM.

[Joko]

If I may please ask, what are the differences for OVNI-B vs vanilla PVS-7?

 

Also, does the OVNI-M housing use the same MX10130 tubes as the OVNI-B?

To answer your questions :

 

OVNI-B housing has manual gain control, 1.25" barrel with thread for filter, 2" barrel with thread for filter too, c-mount & M42 to attach any camera lens and also versatility and flexibility of use that are not possible with PVS-7 housing.

 

No the OVNI-M and OVNI-B do not have the same tubes.

We designed our intensifier tubes, they are called "Astronomy Grade". And there are also huge dfferences in terms of tube specs. Best PVS-7 tubes can reach FOM2000 while our best OVNI-B tubes can reach FOM2700 with extremely low EBI.

Edited by Joko, 04 December 2021 - 12:33 PM.

[a__l]

And there are also huge dfferences in terms of tube specs. Best PVS-7 tubes can reach FOM2000 while our best OVNI-B tubes can reach FOM2700 with extremely low EBI.

I want to explain to a beginner the term "huge" as applied to astronomical observations. This is a rough comparison. 

2700/2000 = 1.35 times 

Stars of 2m are dimmer than stars of 1m by 2.5 times.

But. In technology, this has some progress.

[a__l]

And I will add for understanding the ways to achieve the goal.
Standard SCT with a standard reducer (f/6.3 - that's a more or less decent stars) and Newton f/3.3 with a coma corrector (f / 3.8)
6.3/3.8=1.65 times

[nicknacknock]

To answer your questions :

 

OVNI-B housing has manual gain control, 1.25" barrel with thread for filter, 2" barrel with thread for filter too, c-mount & M42 to attach any camera lens and also versatility and flexibility of use that are not possible with PVS-7 housing.

 

No the OVNI-M and OVNI-B do not have the same tubes.

We designed our intensifier tubes, they are called "Astronomy Grade". And there are also huge dfferences in terms of tube specs. Best PVS-7 tubes can reach FOM2000 while our best OVNI-B tubes can reach FOM2700 with extremely low EBI.

Out of curiosity, is the relationship between FOM 2000 and FOM 2,700 linear? And if not, what is the relationship and how does it tie in with EBI?

 

I guess, if someone was trying to compare, what magnitude / brightness difference one should expect? 

 

Focal ratio impact on magnitude reach /  brightness / resolution is one thing, FOM and EBI impact may be a completely different ballgame!

[Joko]

Out of curiosity, is the relationship between FOM 2000 and FOM 2,700 linear? And if not, what is the relationship and how does it tie in with EBI?

 

I guess, if someone was trying to compare, what magnitude / brightness difference one should expect? 

 

Focal ratio impact on magnitude reach /  brightness / resolution is one thing, FOM and EBI impact may be a completely different ballgame!

That's a very good question.

Contrary to what a__l  wrote, there is no link between FOM and magnitude without considering other specs.

We can not just use the FOM to describe the quality of a tube and the magnitude we can reach, there are several other very important specs.

FOM is not a pure spec, it is the caculation of Resolution multiplied by Signal to Noise Ratio (SNR).

And higher is SNR, more difficult it is to have a low EBI. EBI (equivalent background illumination) as to be as low as possible. Because SNR and EBI are linked. 

For example if you have FOM2000 with very low EBI and FOM2700 with high EBI, you'll see much more and higher magnitude with FOM2000

Same with luminosity, if you have FOM2000 with high luminosity and FOM2700 with low luminosity, you'll see higher magnitude with FOM2000.

 

So what i want to explain is there is no relation between magnitude and FOM.

While it is great to have high FOM, all other specs also have to be very high (or very low for the EBI) to get the best observations. There are around 10 specs, some are more important than others.

 

Of course the best is to have several NV devices to compare these facts.

As a conclusion and as explained by nicknacknock in the previous post "ratio impact on magnitude reach /  brightness / resolution is one thing, FOM and EBI impact may be a completely different ballgame!"

Edited by Joko, 06 December 2021 - 05:00 AM.

[nicknacknock]

Joko,

 

NV is something I will dabble in, once I sort out everything else and feel the "pull" of NV. Ideally, some educating is in order!

 

So, looking for:

 

1. High resolution of the tube in terms of pixel density* 
2. High SNR (same as imaging / EAA - see more with less noise)
3. Low EBI (equivalent background illumination) to minimize background illumination **
4. Describe what you mean by luminosity and its relationship to say pixel size or any other factors that increase brightness / luminosity
5. ...
6. ...
7. ...
8. ...
9. ...
10. ...

 

*   and I assume pixel size?

**  why does high SNR make it difficult to have low EBI. How is EBI calculated?

 

Can you also let a noob know on the other factors? You mentioned in total 10 possible parameters. 

 

If possible to discuss these within the framework of the NV forum rules, please do. Otherwise, I understand it if you cannot provide further information.

 

EDIT: added point 4 from your previous note as one of the factors.

[a__l]

So what i want to explain is there is no relation between magnitude and FOM.

 

This is an unproven statement. The relationship is direct.
This parameter characterizes the sensitivity of the sensor.
In the linear part of the term, the magnitude has an exponential law. I wrote above that this is a rough comparison.
Actually, there are a lot of photos from various sensors on the forum, I suggest Joko give links to photos from FOM2000 and FOM2700. These must be confirmed by FOM from sources independent from the Joko.
Then everyone can appreciate his term "huge".

Edited by a__l, 06 December 2021 - 05:38 PM.

[nicknacknock]

You will forgive me if I prefer to take Joko at face value, since it is his job and he has experience in this, vs your statement which is unproven as well.

 

Can you provide links / documentation to support your assertion that this is a direct linear relationship?

[Joko]

Joko,

 

NV is something I will dabble in, once I sort out everything else and feel the "pull" of NV. Ideally, some educating is in order!

 

So, looking for:

 

1. High resolution of the tube in terms of pixel density* 
2. High SNR (same as imaging / EAA - see more with less noise)
3. Low EBI (equivalent background illumination) to minimize background illumination **
4. Describe what you mean by luminosity and its relationship to say pixel size or any other factors that increase brightness / luminosity
5. ...
6. ...
7. ...
8. ...
9. ...
10. ...

 

*   and I assume pixel size?

**  why does high SNR make it difficult to have low EBI. How is EBI calculated?

 

Can you also let a noob know on the other factors? You mentioned in total 10 possible parameters. 

 

If possible to discuss these within the framework of the NV forum rules, please do. Otherwise, I understand it if you cannot provide further information.

 

EDIT: added point 4 from your previous note as one of the factors.

OVNI Night Vision keeps growing and I'm very busy this week as the workshop is moved to a new place.

So i will answer next week. 

Edited by Joko, 07 December 2021 - 03:13 AM.