OK, let’s get this out of the way at the outset.  Why make a digital Holga?  Because we can, it’s that simple.  I started this project back in my days working at EP Levine, and when the Imacon 96 back was released they talked a lot about how it was adaptable to any camera, even a pinhole.
 

That’s all I needed. 
 

I’ve often told the story about selling the Holga modification.  We joked, Steve Brettler (owner of EPL and my boss) and me, about doing a Holga mod package and selling it online, to sell digital backs as accessories.  It wasn’t until I joined the Imacon user group on Yahoo and in my biography listed myself as the first in history to shoot with a digital Holga with an Imacon back, that Imacon owners started contacting me about selling them one.  I learned an important lesson- know who your customers are.  It’s easier to sell a Holga to a guy who’s already bought the digital back, than the other way around.   I think, all told, we sold about 50 of these kits, and had a blast doing it. 
 

Chances are, you’re going to use a digital back available to you, and you don’t have much choice what the specs are, but in case you have a couple kicking around, this is what will work best... or work at all, for that matter. 
 

The sensor on the back needs to be as close to the film plane on the Holga as possible.  This allows it to focus relatively accurately.  The further the sensor is away from the film plane, the more the focus will shift to a closer focus.  Remember, the focus at infinity is when the lens is the least distance from the film, and as you focus the lens closer, you’re moving it further away.  If the sensor of the digital back is not at the film plane, it won’t focus precisely at infinity.  Fortunately, precision isn’t really an issue with the Holga anyway. 
 

The Imacon 96 was a perfect choice because it had an adapter plate that, once removed, exposed the sensor as the frontmost plane.  Accidentally, the distance from the flange the plate mounted on to the sensor was exactly the same distance as the back of the Holga to the film plane.  All I needed to do was to cut a hole in the removable back of the Holga and attach the digital back. 
 

I ended up cutting the hole with a milling machine with a standard X-Y vise.  You can use whatever you have, a jewelers saw, coping saw, Dremel tool, even an XActo knife.  I’d suggest starting by drilling four small holes on the corner of your cutout- it makes a cleaner cut.  I also removed all the internal baffles, according to Holga tradition, as you can see here.
 

The sensor size is actually the secret ingredient here.  The Holga lens falls off dramatically towards the corners- a crucial part of the Holga “look”.  If your sensor is too small, it’s just going to pick up the middle of the lens field- the sweet spot- and you won’t get the falloff.  Take a look at this- the outer area is the full 6x6 area of the film plane.  The inner area is 6x4.5, the size of the biggest medium format sensor.  Inside that is the Imacon sensor- 35mm square- next, full-frame 35mm, and finally the smaller sensor on many DSLRs.  I added an overlay of the “Holga Effect”.  Ironically, the bigger the sensor, and the pricier the digital back, the more Holga-ish the shots are going to look.  One reason the idea of taking a Holga lens and slapping it on a DSLR doesn't give you that look, is that the DSLR sensor is just too small.
 

The second thing the back needs to be able to do is to use flash sync triggering.  Most (if not all) digital backs that can run on a view camera adapter will have this option, and then it’s a simple case of using your hotshoe on the Holga to trigger the capture.  Get a hotshoe/PC adapter, plug in the digital back, and you’re ready to go. 
 

The sequence for a digital capture with a digital back is like this.  The back powers up, and charges.  The shutter opens.  The digital back measures the charge passing through each pixel, and reads-out.  The shutter closes.  The data downloads to the CF card or computer.  It really doesn’t matter if the shutter is on an integrated camera like a Hasselblad H3D or a DSLR or a Holga- a shutter is a shutter.  This happens all within the duration of the shutter time- 1/60th of a second, for example.  My grandfather used to say a camera is just a box that holds a lens in one spot and a sheet of film in another- same thing here, except we’re just holding a sensor instead of film. 
 

The one last thing is the ability to aim the camera.  For this you can shoot blind, as with a pinhole, make your own viewfinder, or use a viewfinder that’s commercially available.  Holga has a “Holgaroid” viewfinder- the thing that you use when you shoot polaroids- but I just sight over the top of the camera- referencing the same spots.   I’ve also used a Hasselblad “Sport Finder” for capers like this. 
 

That’s it, really, it’s as simple as that.  Set the digital back up for flash-sync operation, and snap away. 
 

Oh, one little note-  when you’re shooting with this rig, hold the camera by supporting the digital back, not the Holga.  I know, I know, but talk about a “duh” moment…