I think shaped bokeh is a really cool idea, but I had never actually tried it. Video #16 of my #100videoclips project shows my first attempt.
This is one of my favorite videos that use shaped bokeh:
Here’s a short “making of” video:
What I Did
My video is “How to,” so it basically shows what I did.
The key is to use a not-short lens with a large aperture, and put the mask you create right in front of the lens.
Any shape you put in front of the lens will block some of the light, but only if it is smaller than the hole in the lens, which is determined by the lens length and the maximum aperture. As explained in this post by diyphotography.net, the size of your mask needs to be less than the length of your lens divided by your maximum aperture.
For example, if you have a 50 mm lens with f/2.0, you can have a shape that is 50/2 or 25 mm.
In my case, I used my best prime lens, but it’s a “pancake” for my Panasonic GH2. Even though it opens to f/1.7, it’s only 20 mm, so my mask (I found out after I started this video) had to be very small: less than 11.8 mm, or no more than 1/2 inch across.
What I Learned
- I knew about using a prime lens with a large aperture, but it’s the combination of aperture and focal length that’s key.
- You can learn a lot more about the specifics of shaped bokeh from diyphotography.net, particularly the page referenced above and this page (create your own bokeh).