Here’s version 1 of the Holga Raspberry Pi Camera – a hackable, programable camera with a 5 megapixel sensor and HD video capabilities, in retro camera form.
My original concept was to do something like this:
And I managed to build something like this:
The Holga is an ultra-cheap medium format camera – if you shop around you can get one for about £15-20 – the model I used for this was the Holga Camera 120N (120 N) (Plastic Lens / Hot Shoe) with the Raspberry Pi Model A – although with a bit of modification it would work with the larger model B. Potentially by soldering the power supply and USB directly to the Pi you could make this a slimmer fit, but I wanted something that didn’t modify the Pi in any way.
The model A Pi fits quite well – you just have to remote the 2 plastic struts inside the case, and peel off the foam that secures the film reels inside the case. I had to remove the plastic panels that enclosed what would have been the flash (my Holga came without one). I cut up a cheap USB extension cable to mount on the top of the camera – and to plug into the side of the Pi. In order to make it fit with the right angled micro USB on the other side I needed to solder and make my own USB cable (you’ll need the shortest USB plug available – I used a poundland retractable USB cable as the source for mine).
If you don’t want to bother with the soldering you could probably just drill holes in either side of the case – there is room, and the plastic is easy to cut through.
I also added a couple of plastic struts to locate the Pi in place – it’s a snug fit so doesn’t rattle around inside the case.
With the Pi removed you can see how it sits in the camera:
The yellow wires go to the flash hotshoe – the green to the trigger button on the side of the lens housing, and the red to the power button.
The camera module sits inside the lens with the ribbon cable carefully wrapping around the board and over to the socket – I experimented with Sugru to hold the camera board in place (which would work) but wanted it to be removable, so opted to cut up a piece of spare plastic and drill a hole for the module to peek through – it’s a fairly firm push fit which holds it in place. The lens can still be rotated a little to make it easy to level the Pi camera.
For the power switch I used the same circuit as for the Motorola Lapdock, and added it to the lens mount. I’ve also added a press button on the other side to use to take photos – this will be (eventually) wired to the GPIO.
Despite it’s cheapness the case feels solid – most of the modifications could be done with a sharp craft knife, apart from a few places where the plastic was thicker or I needed to make holes and a dremel was needed. There’s a lot of empty space inside this case so plenty of room to add things later (I wanted to add a speaker and a few other outputs and inputs, so will do later..)
Overall this was a fun project – all the messy cables and glue are neatly hidden (I went a bit overboard on the glue gun when soldering my USB extension cable) and the case was fairly easy to work with.
The case also has a nice screw mount for a tripod – handy for securing the Pi with camera to things.
Making it more than ‘just a camera’
Replicating a simple Camera with the Pi and Holga (HolgaPi? Piga?) would be a bit boring so my aim with this project is to provide a nice case with the possibility of extending it beyond what I could achieve with a normal compact camera.
At the moment the GPIO isn’t connected to the shutter button or flash trigger – i’ll do this next and write up the method in another blog post.
Things to do:
- Think of a name
- Calibrate the viewfinder
- Write / find some code to make the camera operate over a network. As it lacks a screen the idea of putting all the camera controls into a web app makes sense
- Add an LED indicator to the viewfinder
- Add a speaker and think of some sound effects for the camera to make
- Make use of the flash hotshoe (I’m thinking of using an opto-isolator for this, as some flashes have high trigger voltages running through them)
- Add some more inputs – this could make the basis of a camera trap. Would be fairly easy to make this rainproof. As it is it would work with a Makey Makey…
- Write some code to make the GPIO stuff work. I’m relying on this blog post to learn how.
- Spray it red / green to match with the Pi look, neaten up the lens mount where the glue has discoloured the plastic
- Investigate batteries or solar power
- See if I can add a filter mount
- Send a detailed proposal to the Lomo people to ask them to make a modified Holga case for the Raspberry Pi