The nipkow how small could one be made

[Viewmaster]

I too have been musing over the smallest Nipkow one could make.
About 2 inch dia seems small and could be made....32 lines gives frame height of some .2 inches and width of about .15 inches requiring 32 holes some .004 inch diameter !!!

I have an old Ensign Selfix 120 rollfilm stills camera.
I am musing with taking a photograph of the club's 12 inch Nipokow disk against bright lighting. Arrange camera to Nipkow distance such that it gives a 2 inch dia image on the film.
Process film in very high contrast should give the required 2 inch dia Nipkow disk on the film with the .004 inch holes in the tiny image. They would be accurate as they are a direct copy of the club's Nipkow.

Just cut out the 120 film around image of the disc, pierce the centre hole and there is the smallest Nipkow.....to be viewed with a tiny B/W camera and VDU.
Tiny Nipkow mounted on top of the VDU for show.
Might look quite attractive.
If you only have a 35mm camera one could try a 1 inch dia Nipkow but that might be pushing the grain on the film to resolve the 32 holes.

I daresay all this sounds daft but that's me

[Steve Anderson]

...but that might be pushing the grain on the film to resolve the 32 holes...

If you used a very fine-grain film and the appropriate developer you should certainly be able to do this on 120 film and quite possibly 35mm too. If I were to have a stab at this I would use Ilford PAN F film (ISO 50) developed in either stock PERCEPTOL (finest grain) or ILFOTEC DD-X (maximum sharpness). This is monochrome of course.

Using the above method the resolution that can be achieved is down to less than 5um (micro-metres). So for a 36 x 24mm image results in the approximate pixel resolution of 5000 in the 24mm dimension. At two and a quarter square (120 film) results in nearly 12,000.

It's possible...but what it all hangs on is the glassware, the lens, is it up to the job? It'll need stopping down to it's smallest f-stop and an accurate focus. At Ilfords' PAN F's ISO rating of 50 it could be quite a long exposure. A tripod and remote shutter release certainly required.

The above also generally applies to modern still digital cameras. So it's got a 12 mega-pixel sensor...wonderful...but a cheap plastic lens...marketing...I treat them with the same disdain as accountants...

Steve A.

[Viewmaster]

Further to this idea Steve, the film would be rather flimsy and the bright LED (not an array required , just a single one ! ) would also show through the darker portions of the film even though it was develped to max contrast.

If my memory serves me, fine grain film and high contrast stock don't go hand in hand, but not sure about that.

So two/three sets of images could be combined and registered with each other to help increase the contrast between the clear holes and the black film area.

Also the film's flimsyness could be overcome by sandwiching it between 2 steel/plastic washers whose dia didn't quite cover the 32 holes.
I see little grain worries etc as only need to resolve .004 dia image,
which for film, is quite large. (a very low 10 lines per mm )

Also one could shoot many images on a roll of film all at various exposures etc and pick the best.

Busy at present on my other big project but I am now going to buy a roll of 120 film.
I never ever thought I would be using 120 again in my old Ensign.........I wonder if the shutter still operates !

edit......Is there a tiny B/W camera that is sensitive enough to see the very very dim Nipkow image created by .004 dia holes ?

[Viewmaster]

Well Steve I have ordered a roll of Ilford PAN F film as per your suggestion.

Also bought a new tiny, tiny B/W video camera from ebay for £5. It's only 1 inch but also states it can be externally synchronised so that might be worth exploring re sync to the little disc.

For £5 it's worth experimenting with.........just a cheap stocking filler at this time of the year!

[gary]

it can be externally synchronised

if it can be it has applications well beyond this one, any more information? a link perhaps?

[Viewmaster]

it can be externally synchronised

if it can be it has applications well beyond this one, any more information? a link perhaps?

This is it, Gary......
http://www.ebay.co.uk/itm/260863696255? ... 1439.l2649

BTW, it's PAL only.

Scroll down past the pictures of it down to the spec.
The last box is 'functions' where it states,
"External frame synchronization."

[gary]

Thanks Albert, I wonder if Baird could have imagined in 1925 that in 2011 you could buy, what for him would be a high definition camera, for the equivalent of 93 pence? (and Not to mention FREE delivery - I still can't see how they manage that).

After a bit of googling I notice that a lot of those "surveillance" cameras claim to have "external frame sync" but none explain what they mean by that. As there are only power and video connections it's had to see how it is achieved, unless it is based on something like this:

www.sampson-jeff.com/qprot/d-m4088.pdf

and has some digital connections on the back.

I'll be interested in what you end up with.

[Viewmaster]

Thanks Albert, I wonder if Baird could have imagined in 1925 that in 2011 you could buy, what for him would be a high definition camera, for the equivalent of 93 pence? (and Not to mention FREE delivery - I still can't see how they manage that).
.

It's amazing isn't it. Shipped half way around the world...the 2 plugs on it are worth 50p too.

After a bit of googling I notice that a lot of those "surveillance" cameras claim to have "external frame sync" but none explain what they mean by that. As there are only power and video connections it's had to see how it is achieved, unless it is based on something like this:

www.sampson-jeff.com/qprot/d-m4088.pdf

and has some digital connections on the back.

I'll be interested in what you end up with.

I see your link states that there are both hor and vert timing o/p too.
But the addressing internal registers might be a complexity too far for me.
The camera I have bought is just a simple single o/p but I wonder how one
gets into the externl sync.......we shall see.

Yes Gary, I will let you know how it performs, especially on sensitivity which is critical for my .004 holes. But, unlike normal sized Nipkow discs which need a diffuser set back from the disc, a single ultra bright LED can by positioned right up to the disc to get max illumination in this tiny system.

Just realised that normal B/W film will not be suitable for photographing the club disc against bright light. Either a reversal film is required or shot on colour film.
That's the first of the spanners in the works, although not a big one.

[Klaas Robers]

It's possible...but what it all hangs on is the glassware, the lens, is it up to the job? It'll need stopping down to it's smallest f-stop and an accurate focus. Steve A.

To my knowledge you should not go to the smallest f-stop, as then the optical bending around the small hole of the diaphragm spoils the sharpness. When you do the opposite, a large lens opening, the sharpness is spoiled by the optical errors in the lens. For maximum sharpness you should go to f/5.6 to f/9, depending on the quality of the lens.

As I learned in the past.....

[Viewmaster]

It's possible...but what it all hangs on is the glassware, the lens, is it up to the job? It'll need stopping down to it's smallest f-stop and an accurate focus. Steve A.

To my knowledge you should not go to the smallest f-stop, as then the optical bending around the small hole of the diaphragm spoils the sharpness. When you do the opposite, a large lens opening, the sharpness is spoiled by the optical errors in the lens. For maximum sharpness you should go to f/5.6 to f/9, depending on the quality of the lens.

As I learned in the past.....

Whilst that is true, on a long focus camera such as a 120 rollfilm, the depth of field gets quite small at the larger stops.
On a single lens reflex then one can see if in correct focus, but on older models, like mine, one needs the bigger depth of field obtained on the smaller stops, most especially as it is a close up shot in this application.

[Steve Anderson]

I'm tempted to order a couple of those monochrome TV cameras...just 'cos the may come in useful in the future...a good source for a 625-NBTV converter. No need to get rid of the PAL or NTSC sub-carrier.

I say a couple simply because everything I buy made in China either doesn't work 'out-of-the-box' or fails shortly thereafter. I've had desk lights melt, UPS's catch fire the first time the power fails and power distribution strips (220V type) arc-over internally. All new.

So these days I avoid Chinese-made goods unless I have no choice, in this case these cameras are so cheap it's a case of, "What the heck."

Steve A.

[Viewmaster]

I'm tempted to order a couple of those monochrome TV cameras...
Steve A.

You had better hurry up Steve as 12 have been sold in the last month,
although 10 more are now available.

The guy sells many types of camera and small monitors
One is a spy camera built into a pair of sunglasses.
Another is a tiny camera with built in video recorder. Amazing stuff.

http://www.ebay.co.uk/itm/Small-mini-ca ... 3cbb3bd1a2

Goto to his listing and click on 'other items'

[Steve Anderson]

Goto to his listing and click on 'other items'

I did, and I could see without some form a restraint I would end up spending far too much! So I've given myself a self-imposed 'cooling off' period of at least a few days...if those cameras all get sold in that time, so be it...after all, they fall into the 'Nice to have category', not essential for what I'm doing right now.

Steve A.