3D Printed Rotary Slit-Scan Disc Camera – Part 1

In this video I’m going to use a 3D printer to make an analogue camera. This camera is going to be a little unusual because I am combining two different types of photographic cameras. The first is slit-scan camera which is a type of photographic method designed to remove the time-distortions created by the shutter, for example for use on the finish line of races. And the second is a disc camera – a marketing gimmick as far as I can tell.

The slit-scan stuff is something I’ve worked on with the BBKP guys – who I collaborate with on art exhibitions. We did a photography exhibition back in 2013 and since then, pretty much every year we have done some kind of photography based educational workshop at a museums or art gallery.

Disc-cameras were brought to my attention a few weeks ago by Nathan, who I share the studio with (and who also has his own YouTube channel called OpenTronic) brought back a disc camera from a car-boot sale. It’s quite an unusual camera, produced in the 80s and aimed at the consumer market.

As a format they were a bit of a flop, and for obvious reason. Each disc only took around 15 photos on a hard to process negative, while the standard 36 exposure film spool gave you more photos but could also be automatically processed. The choice was simple.

I can only imagine some bright spark somewhere, thought by putting an analogue photographic method onto a disc – this would in some way re-invigorate photography, and make it feel more futuristic.

The camera looks like a stack of floppy discs, and they’re really no more advanced than a 18th century automaton – mechanically speaking.

That said – the ambition to re-make photography more interesting is not a bad one, and I happen to like the unusual disk shape negatives produced. They remind me of the wide images peering into the Large Hadron Collider. Or the gigantic rotating sets used in the making of Stanley Kubrick’s Space Odyssey.

What I am hoping to do, is producing a slit-scan on a disc will render the time-distortion properties of traditional slit-scan obsolete, because the disc moving quicker closer to the circumference. But firstly I need to design the camera, which I’ll be doing on Fusion 360 and then printing the individual parts out on my AnyCubic i3 Mega.

I’ve already started to design some parts for this camera and I’ve produced a few different versions. This was the first one that I produced and it’s a little large and it took a little while to print out. It’s a direct drive, so this handle here is connected eventually by a screw to this disc which will have the paper stuck to it. And if I make that disc invisible, you can see this section here – if I zoom is, is where the slit will go. It will be made by simply cutting a disc of paper along the centre and sticking it on either side of the slit, going from the top to the bottom. If I remove the lens cap, you can see a window here which will house the lens which I’ll be using from some reading glasses. The problem I have with this camera and this direct drive method is I need to turn the disc very slowly to expose the photographic paper that I’ll be using. Obviously if I was using a negative then I would be able to move the disc by hand and still produce images as negative are generally a lot more sensitive than photographic paper.  What I’m going to show you is the assembly of the first camera and some of the mistakes I’ve made and then move onto the alterations I decided to incorporate into the design.

In theory I could have set up the other printers but this one works so well, I’m a bit reluctant to fool around with the other two. Ok I just pulled that off, and it looks pretty good. A little bit of a flex to it but it’s still warm. I should leave it somewhere flat. You should really leave these on the machine as they cool down. I always seem to get too excited. It looks like a little disc sander doesn’t it.

Ok so this is the lid, I’m currently printing the box section that will fit on this although I kinda pulled this off the printer a bit too quickly and it’s got a little bit of a bend to it. I added this lip around here to try help keep the disc flat. I should have added some going across as well, as you would with injection moulded pieces. Maybe I even needed something on the back of this. Essentially this fits through here but are practically flush now on top. So I don’t think I really needed this ring but I might try and glue it on anyway so all the parts are where I expected them to be.

I made a few mistakes with clearance for what should have been interlocking pieces with this first model. Because of the compression of the first layer which is needed to adhere the PLA to the heatbed, a groove on the turning handle, and lid were a lot narrower than the bits which were meant to fit into them. I’ll leave that to set for a little while and then I’ll glue thing section onto the handle, or if I can, maybe I’ll find a machine screw that will actually tighten in there or throw some glue in there, I’m not sure yet.

Just swapped the machine screw out to get a better purchase. Now it works. It’s a bit tight. It would have been nice if I could have had a gap there and maybe avoided that noise, but everything is doing what it’s meant to be doing. Ok the other thing I need to do is add a lens, in this case from a pair of reading glasses, onto what will be my focusing lens. And I have to admit that noise is really annoying. Haven’t created a mechanism for locking this section onto here at different focal lengths, so what I think I can do is put a bit of tracing paper in the camera where the disc will actually lay inside the box, and just visually look at what’s focuses. Really all I want to know is where infinity is. Ok I’m going to have to use three lenses, so one will end up going on the outside and possibly another back on the inside if I can manage it. So you’re looking at this section here… What I’m finding is the shorter the lens housing, the more reading glasses lenses I need to stack up.

I just wonder like where is it more convenient for you as well? I guess in that corner. That’s Nathans camera. That’s Nathan being squashed by a camera.

I also designed a square hole in the camera body which I was planning to attach the slit too. But it would have been several milometers above the disk and photographic paper, so the effect of the slit would have not worked.

I don’t think that will fit. Try different rotations?

After attaching the lens to the body I used a flush trim bit on the table router to make the opening on the body of the camera the same as the inside diameter of the lens.

And later re-printed a new piece to hold the slit which would bolt onto the same mounting holes as the lens.

I also trimmed the rebate of the camera body, on the table saw so the two pieces could fit together.

The other problem I have is because this section here was printed this way around, the compression of the filament made the groove that this section – this lip, was meant to fit into just too narrow. Instead of trying to widen this I think what I’m going to do is do a few passes on the table saw, and hopefully narrow that down.

Ok it fits together a bit better. One of the corners is not perfect but I think if I was going to use this anyway I’d put a seal of electrical tape around just to make sure it doesn’t pop out, as I don’t have a locking mechanism for the lid.

A DIY camera is not complete without lots of electrical tape.

To find the focal length I placed a piece of opal plastic where the photographic paper would sit and moved the lens until the object I was pointing at – in this case the light fitting was in focus. I use a white pen to mark the lens and labelled the distances upon that.

So I’ve just marked four lines to indicate focal distance. The first one here is 20cm, 25, 35 and 50cm. I can’t seem to get an infinity focus with these lenses that I’ve used on the reading glasses, I think I need to do a bit of reading about how that all works.

This is a left handed scissors.

I decided to make a smaller version of the camera – as the scale of the first model meant re-printing new parts just took too long. I also realised that I should try gear the disc so it would turn a lot slower. I did this by adding an annulus gear to the inside of the disc, and connecting a smaller spur gear to the turning handle which is now off-centred. I drew this up in Fusion 360 by hand. The gear ratio is 100 to 17 – so it takes 5.9 turns of the handle to fully turn the disc.

I’ve just printed the box section of this. I’ll open it. It’s still cooling but the lip and the groove are a lot better suited, this one’s wider here and this is a bit narrower, and they fit together really nicely. I kinda worked that out. Now to try and help avoid warping which is a problem with 3D printed parts, it’s come off the hotbed, and I’m clamping it on to the lid so that will hopefully keep the shape.

This development, alongside silverprint – the place we normally photography supplies from having moved now out of London (like everything else) this time to Poole, of all places – means I am only now just about to test the camera. And no offence to anyone from or around Poole, but if you are from or around Poole, and you want to get into chemical based photography. Well you now have one of the best places on your doorstep.

Ok this is a little area you don’t get to see that often. It’s the darkroom. It’s squeezed between two walls and a supporting arch in the building that we’re based. It’s a really unusual space. I’ve got the camera here, and I’m going to do my first test.

Because of the sensitivity of the photographic paper I am loading it into the camera in the dark-room. If I was using negatives, I would have to do this in complete darkness but photographic paper is a bit more forgiving. The paper is also negative, so the image will have to be inverted or made positive to see details more clearly.

Ok I’m using a bit of electrical tape as a shutter. I don’t know what I’m going to record yet.

Yeah I don’t do clockwise, or anti-clockwise. Ok here goes. Cool.

Oh was the developer on the right? Oh the developer is closest to the door. Ok, that doesn’t look right. Alright I forgot to put the slit in the camera. Oh sheet. It looks kinda cool though. It’s got this kinda moon shape. Ok let do this again. You can see I’ve actually got the slit on there now – that was really stupid.

Nathan is building a belt driven turn table to rotate a large object while taking a slit scan. He sat down on it to see if it could take his weight. I am concentrating on turning the disc as slowly as possible – that’s my concentration face.

Even though the workshop feels quite bright, it will not compare to daylight, and I have to also factor in the speed I turn the disc which exposes the paper, and the thickness of the slit which acts like an aperture. In reality you just have to do a few test and compensate the next time around. On the negative paper everything is reversed. So where I may have paused turning the disc or pointed at a light source, you can see dark lines which means they were exposed (or over exposed), and the light patches of paper, once invested will be dark, which means they were underexposed.

So yet another video has come to a natural end. In the next video I am going to consider planetary gears to further reduce the rotational speed of the disc and continue developing the slit-scan disc camera. If you want to support this channel you can sacrifice your thumbs to the algorithm gods, or support me on Patron where provide additional material to relevant videos. Thanks for watching.

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