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Re: Mechanical camera - need advice

PostPosted: Sun Jul 28, 2019 6:09 pm
by Harry Dalek
smeezekitty wrote:I have a new lens setup. I took apart the lens from a broken camcorder and used only the front part. With a bit of cutting and sanding, it fits perfectly in the hole in the front of the case.
It is much more practical than having the lens on a tripod way out in front. I can turn the lens to focus it although it doesn't change it that much -- probably because how far it is from the disc. It only focuses on objects rather close in.


That was a good idea to use another lens and cover the lens hole out right reduces noise and lets the light from the lens enter .

Yes to check the lens focus to the disk put some white paper on the nipkow placement point it at things at different distance and see where it will work and check the image on the paper if its not in focus it never will ...

When trying a lens its some thing that's has to be worked out by testing ... its a 32 line camera so your not going to need long distance focusing you want it to focus close arms length or 2 at most so you can fill the screen.

Try the paper test and see how in focus a object is on that white sheet you might have to adjust the lens distance or the nipkow mounting position .

I tended to do this in my garage with the door open and with sun light the focusing on that white sheet is easy but you want close so a lamp and test card is more wanted here ....we want reflected light ...Troys nipkow camera on this forum he shows this procedure .

Re: Mechanical camera - need advice

PostPosted: Sun Jul 28, 2019 11:47 pm
by Klaas Robers
Or try a single white dot as an object. Use al small bike lamp, or a small LED on a black back ground. Then you will see the "response" of the camera on this small dot. Yes, I understand that you want to see a picture of something, but a picture is built up from single dots. And with the dot you can check your focus easier.

Re: Mechanical camera - need advice

PostPosted: Mon Jul 29, 2019 4:23 pm
by Harry Dalek
One thing i forgot to mention , i did choose my used lens by a test alone that is how big is the focal area was on the paper as i wanted the area size about that of the nipkow scan ,mine were always cd size nipkows so the wanted focus area wanted was tiny ...yours would be postage stamp size yes ?

Re: Mechanical camera - need advice

PostPosted: Wed Jul 31, 2019 7:17 am
by smeezekitty
I am quite sure the optical focus is okay at least in close distances. It focuses in the 20-50cm range depending on turning the focus ring. Still quite close -- can't even get a whole human face sized object in focus.
I feel that the blurriness is most likely an effect of aperture size and the frequency response of the sensor.

yours would be postage stamp size yes ?


Yeah, it is about 18mm wide.

Re: Mechanical camera - need advice

PostPosted: Wed Jul 31, 2019 6:04 pm
by Harry Dalek
smeezekitty wrote:I am quite sure the optical focus is okay at least in close distances. It focuses in the 20-50cm range depending on turning the focus ring. Still quite close -- can't even get a whole human face sized object in focus.
I feel that the blurriness is most likely an effect of aperture size and the frequency response of the sensor.

yours would be postage stamp size yes ?


Yeah, it is about 18mm wide.



OK Yes i would agree your nipkow holes might be to large ...Andrew i recall put tape or foil over hes nipkow with larger holes once it had a hole the correct size and he could move it around to line up the scan lines you could use the idea to fix your large holes with a smaller one and see .
Getting there i expect to see you via your camera soon ok these problems make life interesting ! :wink:

Re: Mechanical camera - need advice

PostPosted: Thu Aug 08, 2019 12:40 pm
by smeezekitty
I made a new disc with 0.6mm holes (instead of 1mm) which gives 20% overlap and it helps slightly but it is still kind of blurry. No amount of adjusting focal lengths will make it sharp either. I'm learning to a sensor problem

Re: Mechanical camera - need advice

PostPosted: Thu Aug 08, 2019 2:40 pm
by Steve Anderson
Suggestion...knock up a 555 in astable mode running at around 1kHz which then drives a red LED, aim the LED at the sensor without the disk in the way. If you have a scope have a look at the edges to see what the rise/fall times are from the output of the sensor/amplifier. Ideally they should be under 30us for a 10kHz bandwidth video signal.

If you don't have access to a scope, you're a bit stuck.

Steve A.

Re: Mechanical camera - need advice

PostPosted: Fri Aug 09, 2019 5:42 am
by smeezekitty
Steve Anderson wrote:Suggestion...knock up a 555 in astable mode running at around 1kHz which then drives a red LED, aim the LED at the sensor without the disk in the way. If you have a scope have a look at the edges to see what the rise/fall times are from the output of the sensor/amplifier. Ideally they should be under 30us for a 10kHz bandwidth video signal.

If you don't have access to a scope, you're a bit stuck.

Steve A.

The results are a miserable 5-10mS

I am using an aggressive high pass filter in software which is how I get a usable image in the first place so I knew it was going to be bad. But this is worse than I expected

Re: Mechanical camera - need advice

PostPosted: Fri Aug 09, 2019 11:26 am
by Steve Anderson
As the Mythbusters team would say, "There's your problem!"....or at least the first one...without knowing what sensor or amplifier you're using I can't help much further...

Steve A.

Re: Mechanical camera - need advice

PostPosted: Thu Aug 22, 2019 12:28 am
by Harry Dalek

Re: Mechanical camera - need advice

PostPosted: Fri Aug 23, 2019 6:17 am
by smeezekitty
Harry Dalek wrote:http://www.retro-forum.com/viewtopic.php?f=15&t=248719

http://www.retro-forum.com/viewtopic.php?f=15&t=243584

http://www.retro-forum.com/viewtopic.php?f=15&t=235874

Same sort of idea different construction

The image quality / sharpness is remarkable! I don't know how I would even make a disc that good.

Also, might be one of the most french things I have seen in a while

Re: Mechanical camera - need advice

PostPosted: Fri Aug 23, 2019 1:54 pm
by Harry Dalek
smeezekitty wrote:The image quality / sharpness is remarkable! I don't know how I would even make a disc that good.

Also, might be one of the most french things I have seen in a while


Yes really quality the disk must be laser cut its impressive ..if i come across any thing else i will post up .

Yes we tend to stick to our self's and don't think the rest of the world must be a little interested in mechanical television also ...the French had a long history with early television also.

http://www.retro-forum.com/viewtopic.php?f=15&t=22862

Beautiful images page 3

Re: Mechanical camera - need advice

PostPosted: Thu Aug 29, 2019 7:52 pm
by Klaas Robers
Be aware that when you make a Nipkow type mechanical camera that the "optics", the taking lens, should be at the other side of the disc, so at the left side if you look from the camera man's position, and on the right side if you look from the televised object's side. That is because the taking lens rotates the picture by 180 degrees. If you don't do that, the curvature of the Nipkow disc is happening twice. If you do it correctly, then both curvatures eliminate each other.

The NBTV HANDBOOK describes in chapter 26 "Standards" what is ment. Look at http://www.nbtv.org/standards.htm to read that chapter.

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Re: Mechanical camera - need advice

PostPosted: Fri Aug 30, 2019 3:18 pm
by smeezekitty
Harry Dalek wrote:
smeezekitty wrote:The image quality / sharpness is remarkable! I don't know how I would even make a disc that good.

Also, might be one of the most french things I have seen in a while


Yes really quality the disk must be laser cut its impressive ..if i come across any thing else i will post up .

Yes we tend to stick to our self's and don't think the rest of the world must be a little interested in mechanical television also ...the French had a long history with early television also.

http://www.retro-forum.com/viewtopic.php?f=15&t=22862

Beautiful images page 3


The early attempts in the thread have disc qualities much closer to what I'm accustom to.


Be aware that when you make a Nipkow type mechanical camera that the "optics", the taking lens, should be at the other side of the disc, so at the left side if you look from the camera man's position, and on the right side if you look from the televised object's side. That is because the taking lens rotates the picture by 180 degrees. If you don't do that, the curvature of the Nipkow disc is happening twice. If you do it correctly, then both curvatures eliminate each other.

The NBTV HANDBOOK describes in chapter 26 "Standards" what is ment. Look at http://www.nbtv.org/standards.htm to read that chapter.

Yeah, I do have this correct.

I haven't had much time lately so I haven't got around to experimenting with other image sensors.

I also cannot get the lens close enough to the disc in order to focus on more distant objects (i.e. to get a full face in frame). I'm not really sure how I could solve that since the case of the device is so thick

Re: Mechanical camera - need advice

PostPosted: Sat Aug 31, 2019 10:29 pm
by Harry Dalek
I used a old video camera lens zoom and all it had to focus to the tiny vidicon target face similar size distance of the nipkow and gave some adjustment to the focus at different distance problem..
Might have to drill the lens hole to a different size for what your using to get closer to focus mounting that lens you have ..optic part was for me very hard till l just experimented with different lenses and just focusing to a paper screen that gave me an idea what would work and at the wanted focused image size.
Yep having time for this is a pain when having to do life stuff