Design and build

Here is the camera obscura as it is today :

The camera obscura

See below to see how I built my first obscura!

My first camera obscura was built using a 3x3m gazebo, bought off gumtree. I then sewed lots and lots (and lots) of curtain backing fabric to fit like a sort of tent inside it.  Here is a picture of it, and below – pictures and notes from the build. The camera was built for The Pinhole Pedallers – which packed the obscura onto bicycle trailers and set it up to at South West’s most beautiful landscapes to celebrate and photograph them. See the camera obscura page to see how I am using it now.

The first in situ test of the obscura
The first in situ test of the obscura

The Build

Gazebo

As the obscura needed to be fully collapsible and light enough to tow by bicycle ( see the pinhole pedallers link!) I thought that using a structure of a gazebo could be perfect. It proved to work well, I bought a second hand one off eBay and designed the fabric tent around it.

Tent construction

The construction took a pretty long time – mainly because I didn’t know anything about sewing (but soon learnt) and I only had access to a small domestic sewing machine (I later learnt of large industrial machines that would have the job done in a flash!). But! We persevered, drank tea and got through reels of thread until the sewing was complete. Next, we had to line the joins from the inside with gaffa tape to cover up all the holes that the sewing had made, and add a bit more strength to the structure.

The fabric I used is designed for backing curtains, and claims to be completely light tight. This is a bit of a lie, as it does in fact let light in through many many tiny pinholes. However, it was more that sufficiently light tight, especially when using a large, bright lens. Half way through the construction I came across some light tight fabric that was backed with charcoal on the inside – I had thought I had struck gold as this would reduce reflections within the camera – but in fact I found this fabric even less light tight, and not as had wearing as the normal cream material. Avoid! The curtain backing fabric is fairly light, which was important  – the gazebo structure is not designed to take weight in this way, and so it needed strengthening in certain areas such as the joints nearest the top.

I used Jupiter rings to attach the fabric to the gazebo structure (I later added more as it didn’t hold shape too well). These are super easy to fit – and then made some simple buckles.

Lens

As the space is so big – I knew I would need a lens with a fairly large diameter to make a bright, clear picture. A friend of mine happened to be selling a telescope with a lens cell that matched perfectly. The 5 inch lens is off a refractor telescope and has a focal length of 100cm. It gives a beautiful crisp image! fitting a tripod mount was pretty straightforward too, allowing me to attach a study manfrotto tripod safely and securely. One day I will put the telescope back together and look at the stars..

Focussing

Inside the camera (sorry I couldn’t find a clear picture of this) there are two lines that hold the focussing screen. This allows the screen to slide forward and back to focus on subjects closer than infinity. It also allows a bit of play – enabling you to demonstrate what happens when the lens and screen are not parallel to create some funky tilt shift effects. The screen I used most of the time is actually an old blind that was perfectly sized for the job. Also – the material lets a little light through, enabling groups to enjoy the image from both sides. I have also got some heavier, brighter fabric that I hang when light levels are lower – the more reflective surface makes the most of the light which is really needed when I’m working inside.

Extras

As the obscura was going to be set up outside and with members of the public having a look inside, I really needed to make sure it was secured nicely to the ground. It’s a big structure, and I didn’t want to send a family floating across Dartmoor in a stiff wind. I attached guy ropes to various points on the obscura allowing us to see off some winds but this is still a bit of a weakness I’d like to work on some more.

Thank you

Big big thank you to Louise, Iona, Jack, Alex, and Mum (for the loan of the much abused sewing machine)

I also wish to thank everyone who contributed to my crowdfunding campaign to get the project off the ground – it would have been impossible without your support and enthusiasm!

Once again – if you want to see more pictures of the obscura along with images made with it – have a look at the project specific site – The Pinhole Pedallers .

I am currently designing and building my second camera obscura. It’ll be a little smaller and reflect light from above. I am aiming for a more intimate design, with interchangeable lenses and I want to use the wind to introduce an element of motion to the projection.. Exciting times!

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