I had a bit of fun this weekend constructing a pinhole lens for my camera. For those that don't know, a pinhole lens is a very simple construction that can turn a high tech digital camera into some sort of high tech camera obscura.

There are two difficulties in building a pinhole lens. The first one is finding a suitable material to build it out of. Many people on the internet recommend "brass shim stock", but finding some is easier said than done. I eventually found a package of miscellaneous brass shims at a hobby store in Kitchener.

The second difficulty is punching a perfectly circular pinhole in the brass. Due to the dimensions of my camera, I needed to punch a hole exactly 0.2mm in diameter in order to get the best image quality. Unfortunately, the smallest sewing needle I could find was almost 0.5mm in diameter, so I had to be really careful. It took me three tries before I got something close, and I didn't want to risk widening the hole by trying to make it circular, so my results are somewhat suboptimal.

I have set up a small web page explaining my efforts in more detail.

Anyway, today I decided to take my "new lens" out for a spin, so I ventured into Victoria Park and set up my tripod on a bridge. Unfortunately you can't take hand held photos with a pinhole lens, because it does not let in enough light. The focal length of my camera lens is 50mm and the diameter of the pinhole is about 0.2mm, which means the aperture is approximately f/256!

Another side effect of having such a small aperture is that any dust on the sensor becomes instantly visible. I just cleaned my sensor a couple of weeks ago and the pinhole lens revealed a huge hair on it! (I have photoshopped it out of this image, but I left in all of the other dusk specks.)

So, this is a view of Victoria Park, including a bench and some ducks, taken with my new pinhole lens, the cheapest lens in my collection. :)

Technical details: This was shot with my Rebel XT + 50mm pinhole lens at ISO 200, f/256 for 5 seconds. I increased the saturation slightly and applied massive sharpening in Photoshop to get the final result.

Comments

Damn, that is really cool.  Your sensor isn't that dirty, BTW, I've seen worse,
a lot worse.  Can you share some pictures of your pinhole camera?

OK, I finally found some time to set up a little website with some images and
descriptions of my pinhole lens.  It can be found here:


http://anttila.ca/michael/pinholelens/


Enjoy!

Thanks for the time to set up the website.  Very cool. We learned a lot.