Thursday, May 14, 2009

My Digital Pinhole Camera

I have never seriously pursued pinhole photography, but idea of it, and the soft dreamy scenes have always appealed to me. One day I got this wild idea to make a pinhole lens for my D300. So, without consulting the all mighty internet for ideas, I set about making this lens. Whatever the outcome, I wanted a lens that was professional looking, and not something like a cardboard tube with aluminum foil taped over the front or something like that. To me, this dictated that the lens had to mount to the camera on the Nikon F mount. The only items that I could think of that could mount to the body of the camera were a lens or extension tubes used for macro photography. If I wanted to use a lens, I would have to strip it of its glass, or remove the mount from the lens and somehow attach the pinhole to the mount. I looked at my small inventory of lenses, and though I had some real cheap lenses, they all worked, and I couldn't make myself disassemble one. That left me, in my mind, two options. Try and find a broken or very cheap lens (I was thinking $5-15 is my budget for this project) or find really cheap extension tubes. For some reason, I thought a set of extension tubes would run me $50+, so I didn't bother to look at what was available. Instead, I search craigslist, and ebay for broken lenses. No luck. On a whim, I search ebay for extension tubes and found a ton that were only $10 (that included shipping). So I bought a set. Of course it was coming all the way from China, and I didn't expedite the shipment so it took about 2 weeks to get the extension tube set in the mail. My expectations for this product was fairly low, and I pretty much expected them to be made out of plastic, but they are aluminum. Even still, I am very careful not to cross thread them or try and tighten the various extension tubes to much since I am sure the threads will just get torn apart.

With extension tubes in hand, how do I turn them into a pinhole lens? I am lucky and work for a medium to large machine shop and a friend of mine who is a machinist offered to make me something if I drew up a print. So, 2 minutes to draw something up for him, and a day for him to machine it for me I had a part that looked like a lens cap that as threaded and could be screwed onto the entension tubes. Below are some pictures.

Here is the extension tube set with the aluminum pinhole adapter.




For those not aware of how extension tubes work, the tubes are a set of 5 parts, first part has the nikon body mount on one side and threaded on the other. Three parts ar basically just spacers that thread onto the first part. The last part threads on the end and the lens mounts onto it. So the pinhole adapeter is threaded to screw onto any one of the spacers.

Here is another image with the extension tubes and adapter.


Here is a picture with the adapter screwed onto the end of the extension tube.



So now I need to make a pinhole in something. My first attempt was using aluminum foil like most pinhole cameras are made with. The results were less than desirable. At first I thought this project was all for not. I was not naive to think that I was the first one to come up with this hair brained idea, and given my poor results, I decided to look on the internet and see how other people's pinhole cameras turned out. I found one guy who punctured a hole in a can and seemed to have the image quality that I wanted mint to have.

Here is a sample image using the aluminum foil.


So I took a coke can and cut it up, sanded it on both sides and used a thumb tack to make a hole. The idea, when making the hole, was to make the smallest possible hole. So I tried to stick it in just enough to start penetrating the aluminum. Since the pressure of the pin dents the aluminum, I sanded the front and back one more time.

Here are some of the tools I used.


Here is a macro shot of the hole (using the extension tubes as intended!).


Now I need to affix this to my pinhole adapter. This image has a close up of the hole along to the top since its difficult to see.


Now for a picture of the whole rig on my N80 film camera.


Pretty sexy for a pinhole camera... well I think so anyways, but I am a bit of a photo geek.

So how does this new hole compare to the terrible picture above? Check it out!

Yeah, its soft, but much better than the other, in my opinion. I even refined the hole a bit, and made one a touch smaller and got an image that was a little better. These small images may make it difficult to see the difference but here is a comparison anyways.

When using the aluminum foil, my hypothesis is that the pin creates a ridge of displaced material on one side of the pinhole. This ridge interferes with the image quality, but when using an aluminum can, the ridge can be sanded away, and the image quality is much improved.

Now I need to take it into the field and really play around!

Until next time...

Matthew Eddy
Photographer
http://www.oil-rigs.net/