Holga 120 D

This is an update to my original Raspberry Pi Holga camera case project.

Earlier this year Holga Direct created a digital version of the Holga – the 120d as an April fool joke – although my version lacks the 73 megapixel sensor and retina back display it does actually exist, can take nice pictures and is fairly easy to build yourself if you’d like to give it a try.

The aim of this is to build a neat case which fits the Raspberry Pi and camera module, and to do a bit of experimenting with the GPIO (General Purpose Input and Output) pins to use them to control various aspects of the camera. Lacking instant feedback and having no idea what you’ve captured until you take it home also fulfils some of the ideas behind retro analogue photography made popular by Lomography. It also looks a bit hipster.

This is a fully working Digital Holga 120d – it used the case from a broken Holga, unfortunately it doesn’t use the original plastic lens (although I have kept this) as the Pi Camera board has it’s own built in lens, however it is now possible to use screw on lenses and filters.

The case is now finished but I have made a few changes since my last post:

I’ve lost the external USB port as there wasn’t quite enough space inside the case to fit the USB plug – I am now using a nano wifi adapter inside the case – specifically the Edimax EW-7811UN adapter which works well with the Raspberry Pi model A and fits inside the case.

Along the way I’ve added a few extra parts:

• A 49mm adapter ring on the front lens – it is now possible to add filters – this is a zomei 46-49mm adapter ring (similar to this one) which screwed in to the original Holga plastic lens after using a dremel to sand down the holga lens until it fitted.
• 3.5mm plug for external camera trigger – this is a stereo headphone socket with 2 wires attached. Am using a mono 3.5mm cable to use as a cable release driver as I think it’s some kind of standard.
• led indicator (in the viewfinder – which glows red to indicate a picture is being taken )
• Optoisolator flash circuit – this is an LED attached to an image sensor – the model I’m using is rated to control very high voltages.
• A 3 position rotary switch – to select between video, still photos and program mode. This is a 12 way switch so i’m only using a few of the contacts. I used a big chunky switch I found on ebay which makes a satisfying click when you turn it – it did fit after a dremel was used to cut a larger hole. I’ve used a tap washer to fill the gap between the switch and the camera case.

I’m currently powering this using a (rather big) Anker USB battery – will likely use something smaller in due course but the Anker battery seems to last forever and powers the Pi with the Wifi adapter with no problems at all.

The next step is to build the hardware to connect the various inputs and outputs to the Raspberry Pi. I’ve been experimenting with these using breadboard and hope to solder it all neatly together – with details – for my next project post. Essentially I need to wire 3 switches (shutter, 2 rotary switch positions) and 2 LEDs (indicator, optoisolator) to the GPIO.

Then finally there’s the matter of some software to pull it all together. At the moment I’ve been testing using the rather useful BerryCam iOS app – although it seems ironic to be using a device with it’s own much better built in camera to control the camera of another computer remotely, it’s a useful app to test things with. If you use the instructions in the first bit of my post about using the Pi as an Adblock server you can also set the IP address to be the same each time.

Update: I’ve added the inputs and 2 LED outputs to the GPIO on the Raspberry Pi – check out this post for more details, circuit diagrams and code.

Finally here’s a selfie in the mirror: