64 lines HD mechanical camera ??

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64 lines HD mechanical camera ??

Postby Gregory » Wed Apr 14, 2021 6:38 am

I was just wandering if it is possible to build a reasonably portable mechanical camera capable of 60 or 64 lines resolution, but not using a flying spot system, so the camera could be used in outdoor light conditions.

Would this be feasible for home construction or too difficult? Has any one tried this or have there been any previous posts of members constructing something similar?

Any info or advise would be most helpful.

From what I read so far it seems it would be difficult to obtain sufficient light for a 64 lines system.
I have no idea where to start from but I think it would make an interesting construction project, if it was at all possible.
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Re: 64 lines HD mechanical camera ??

Postby Harry Dalek » Wed Apr 14, 2021 4:55 pm

Gregory wrote:I was just wandering if it is possible to build a reasonably portable mechanical camera capable of 60 or 64 lines resolution, but not using a flying spot system, so the camera could be used in outdoor light conditions.

Would this be feasible for home construction or too difficult? Has any one tried this or have there been any previous posts of members constructing something similar?

Any info or advise would be most helpful.

From what I read so far it seems it would be difficult to obtain sufficient light for a 64 lines system.
I have no idea where to start from but I think it would make an interesting construction project, if it was at all possible.


PMT camera success Nipkow 32 line willing to work smaller could do 64
viewtopic.php?f=20&t=2139&hilit=PMT

Mirror camera almost i did not take into account this all had to be done in a light proof case even just testing stage ,the idea could of worked and would of been multi system and small. Idea was similar to your current monitor a line mirror and a framing mirror
viewtopic.php?f=1&t=1795&hilit=mirror+camera

I can't say apart from flying spot there are to many others on the forum that have made a mechanical direct light camera i think Troy had a go also at a 32line one ,i have made flying spot and direct light mechanical NBTV cameras and vidicon multisystem all electronic .

So yes i can't see why its not possible a light proof case and you are almost there :wink: ,only light from the lens focused to your scanning disk or mirror ,so there's a bit of optics to work out and you pretty much know the rest ...Have a read and think about which way you want to go Nipkow or mirrors .

Well i have not heard that on 64 line but i suppose its logical half the light than a 32 line would produce ,well if you use a nipkow ...i used a PMT behind mine you will have no problems with light levels with those ...I think troy used a solar cell on he's big desk size camera using a record .
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Re: 64 lines HD mechanical camera ??

Postby Gregory » Sat Apr 17, 2021 7:51 am

Thanks for the info, and from what I understand as with the televisor the camera can use the Nipkow disk or mirrors , assuming it will be used under normal light conditions, an not in the dark with a flying spot.

With the nipkow disk I believe from 32 to 64 lines, the light level will be a quarter, as the spot area will be this.
The mirror system seems more appealing, and I like the idea of the vibrating mirror for the frame scan, and at 12.5 hz it should be possible to follow a sawtooth path, with suitable mechanics.

The point that worries me is how large the mirror drum will need to be. The normal view angle of a camera is around 60 degrees, so if I am not wrong this would need a 12 sided mirror. I am not sure how large the image on this needs to be to work correctly with sufficient sensitivity.
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Re: 64 lines HD mechanical camera ??

Postby Harry Dalek » Sat Apr 17, 2021 8:47 am

Gregory wrote:Thanks for the info, and from what I understand as with the televisor the camera can use the Nipkow disk or mirrors , assuming it will be used under normal light conditions, an not in the dark with a flying spot.


Theres no reason why you couldn't do a small 2 mirror drum version of your monitor for a camera if you want to go small and multi system,but would have to be in a light proof box again apart from the lens system or just lens focusing the image to it .


With the nipkow disk I believe from 32 to 64 lines, the light level will be a quarter, as the spot area will be this.
The mirror system seems more appealing, and I like the idea of the vibrating mirror for the frame scan, and at 12.5 hz it should be possible to follow a sawtooth path, with suitable mechanics.



The vibrating mirror has on flaw ..line fly back is not instant as with a rotating mirror drum so has to run twice the speed so best to make the framing mirror this idea .
Cameras are hard but you never know with these things till you try and work out the problems ,one thing i was not expecting on the nipkow side is does not matter so much how good your nipkow holes are lined up it the will be no gaps in the resulting video ,only mechanical sync is more of a problem any vibration makes the sync pulse width sightly different so the lines will line up wavy , mounting the disk mirror on some thing like a vcr head or HD drive motor where there will be none of that is the way to go !
Light levels for the nipkow will be small anyway 32 or 64 line amplification and your pick up device should be sensitive enough and just use more light all that has to be experimented with ,i used a PMT which can detect a photon ,i have only really used solar cells on flying spot pickup camera but as i recall Troy did it .
Panrock i forgot has a 3 colour PMT camera on the forum as well.

The point that worries me is how large the mirror drum will need to be. The normal view angle of a camera is around 60 degrees, so if I am not wrong this would need a 12 sided mirror. I am not sure how large the image on this needs to be to work correctly with sufficient sensitivity.

[/quote]

Comes down to optics ! my nipkow PMT camera i used a old video camea lens to focus the scene on nipkow scanning raster size which i made from a cd dvd the resulting image was tiny to the nipkow but all the area was there on the scanning raster ..its your lens system construct your camera for the lens system ..small is not that much of a problem .
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Re: 64 lines HD mechanical camera ??

Postby Gregory » Sun Apr 18, 2021 3:29 am

From all the info I've read, I'm beginning to understand that the two most critical factors are:

1) Good light sensitivity with a high signal to noise ratio
2) A very stable speed so that the sync pulses and video signal are accurate

What may be a good starting point would be a narrow beam lens such as a telephoto or telescope type together with a photo sensor in a light proof box to test for the sensitivity.

If this is satisfactory then one could deflect by placing line and frame mirrors in front of the lens to scan the area required. If stepper motors are used for this, as in my televisor, then the oscillators could be crystal controlled to ensure stable speed.

Well that's the theory, maybe, but first must get the televisor finished first.
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Re: 64 lines HD mechanical camera ??

Postby Harry Dalek » Sun Apr 18, 2021 8:48 am

Gregory wrote:From all the info I've read, I'm beginning to understand that the two most critical factors are:

1) Good light sensitivity with a high signal to noise ratio
2) A very stable speed so that the sync pulses and video signal are accurate

What may be a good starting point would be a narrow beam lens such as a telephoto or telescope type together with a photo sensor in a light proof box to test for the sensitivity.

If this is satisfactory then one could deflect by placing line and frame mirrors in front of the lens to scan the area required. If stepper motors are used for this, as in my televisor, then the oscillators could be crystal controlled to ensure stable speed.

Well that's the theory, maybe, but first must get the televisor finished first.


Since you are thinking about making it small ,as with my try it seemed the old video zoom type lens was handy and gave the focus size scan but comes down to size of your scan area what ever you build and try and match it size wise with the lens system you can find .
More lensing does make it dimer but it still worked in side in room light ,
Well yes stable speed for of cause syncing but more so for using feed back sync so that the disc or mirror does not wobble at all thus a very accurate mount here such as a vcr head or HD motor mount would give and no warping in a disc if you go that route .
A trick i used to over come the problem was i used the feed back sync to get the disc to sync but didn't use it for the video signal i swapped switched to a crystal made 400hz sync just used that to add to the video signal worked a treat ! ; 0 ) a nice stable video .
I found even a tiny scratch in the black case ( it was painted matt black on a transparent case ) would show up as static in the video so i knew every time that happened !
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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