Fun With Bokeh

Bokeh refers to the out-of-focus shapes formed in a photograph by the camera's aperture, particularly those of background features. I had found various instructions on the web on how to construct your own shaped filters, but none that would allow me to easily change these filters on the go. 

After some thought I came up with a useful, reusable method for easily switching out shaped filters. This method is documented here.

You will need:

  * A camera. Any DSLR camera should work; point-n-shoots tend to have quite small lenses so may not work so well.
  * A lens for which you know the key measurements: focal length, and maximum aperture. I used a 50mm f/1.8 canon lens. Something with a large aperture relative to its focal length will probably work best.
  * Black construction paper
  * White glue (Elmer's or similar)
  * Scissors & sharp craft knife.
  * Pencil, ruler, and (optional) pair of compasses.
  * A cheap UV or similar filter to fit your chosen lens (optional) Why? I wanted to be able to permanently stick the filter holder in place without ruining a good lens. I bought the cheapest UV filter I could, about 99 cents on eBay!

Step 1: Calculations

The first step is to determine the maximum size of your bokeh filter design. This size will be determined by the maximum aperture of your lens. Take the focal length of your lens, and divide it by the maximum aperture size, for example:

  50mm / 1.8 =~ 27.7

I went with a 26mm diameter to be safe.

You'll also need to measure the inner diameter of your filter or lens body.

Ok, maths over, on to construction.

Comments

[Nano_Burger]

I've seen decorative paper punches that I guess are designed for scrap booking.  Hearts, paw prints, aircraft, stars etc.  They could be used for the aperture of your "bokah generator."  Save a little time and folks who are not good with an exacto knife.

[Rimwulf]

if you have a camera phone you may (or not, haven't tried it) use a laser light filter (the ones that change the look of the laser) over the lens on the phone.

[WhyIsThisOpen]

I finally got around to trying this. Also, for anyone else using a 50/1.8 lens, a US quarter is about 24mm so it makes a nice template for the center region.

[avatar_i]

Actually, BOKEH was originally an 'Art' form whereby the WHOLE picture was blorry- using a shalow depth of field [what most people now call bokeh] with camera movement, rendering the entire picture blurry.

Bokeh = blurry

I dontt know when the name was re-defined to be another way to emloy shalow depth of field [shallow depth of focus is more precise term].

Virtually any lens over 50mm will give you a very shallow depth of focus, the longer the focal length the more blur.

Shallow/ultrawide lenses have a greater depth of focus, so sharper pictures at any distsnce.

piratemonkey mostly got it right.

[Malarette]

Nice work. Here's my own tutorial about this with maybe a few more details: http://dianeazais.wordpress.com/2011/01/31/creative-apertures-2/

[Lftndbt]

Ok, i'm totally missing something here. If you stick a cut out like that in front of your lens, does it not just allow the light to pass through your shape giving you a sillouette which you can see through?

I don't understand, how you get the multiple lil' tree effect.

I would love to try this on my DLSR, but I am missing something.
I just made a rudementary version, before I posted and all I get is a normally square framed picture, now framed by the cut-out shape. Not even close to the picture you provided. Could you go into a lil more detail on the actually use of the device. Are you taking multiple exposures? I'm lost.

[piratemonkey]

 It's a single exposure. The key to getting the cut-out to appear is using a shallow depth of field, which you can do either by setting a wide aperture (I use f/1.8, but use the largest you have), or by ensuring the background is much farther away from the camera than the subject - the narrower the aperture, the greater the distance must be.

You might have better luck using either the Av or M setting on your camera, and setting as wide an aperture as your lens allows, and with as great a distance between foreground and background as you can get.

[Lftndbt]

I'm using f/2.8 so ap is wide.
I shoot, I get a one silouette of the slide not a mirade of the shape speckled all over the object being shot. 



....


ok I get it now, really only works in dark environments where there are illuminations. For every light on the tree, it is changing the incoming glob illumination in the slide shape.

Good for christmas trees an such, but what else could you use it for? 

[rhino]

Make outdoor areas with patches of light at night turn into fanciful flying saucer movies. Just manually rack the lens out of focus and shoot away. With a UFO filter shape on of course.

[piratemonkey]

Yeah, it does help if the out-of-focus objects are somewhat brighter than their surroundings. As to uses, just off the top of my head how about

- light reflecting off water 
- sunlight through trees
- distant city lights

[lotusduck]

-When using flash on falling snowflakes

[hairyneil]

Ooh, good plan

[trifle]

lovely, i hope it works with my cam

[tobster9103]

I just got into photography and I love this! I made my slide holder removable by cutting it to fit tight and not gluing the holder to the lens filter and putting a piece of tape to pull it off.

[hairyneil]

This is awesome!

I got my gf (she's much better with a scalpol) to cut out a goatskull ( \m/ hehe )
Taken with a Nikon D200 and 50mm 1.4
<img src="http://farm5.static.flickr.com/4055/4355332633_a76bfa9046.jpg">

I've also tried this with a 18-70mm 3.5-4.5 but either the 3.5 isn't  wide open enough or the 18 is too wide an angle. Would further away lights/smaller cut out help do you think?

[MistressX956]

Awesome, been wondering how it was done! Thanks!

[Weissensteinburg]

 Cool! They make glasses that do the same thing...any word on how they work?

[piratemonkey]

 Well, the camera/ lens follows the same principles as the eye, so I would imagine the glasses are constructed along the same lines as used in this instructable - a shaped aperture that causes in-focus objects to appear correct, if slightly dark, while blurring out-of-focus objects in to the desired shape.

[Rimwulf]

actually they use micro printing 100s of the same picture printed the lens on the classes. though all the eye only needs one printed picture in the way to work it has 100s when you move your eye to look in a different direction; although the principles same it my no means uses focus or lack of to accomplish this feat, but instead it relies purely on distortion. the same is applied to laser light filters. dozens of micro prints but only one picture comes out.

[WhyIsThisOpen]

Very cool. I will have to try this.

[jessyratfink]

 How pretty! I especially love the hearts, that's adorable. :)

[mrmath]

I'm guessing you can't do this with a standard point and click type digital camera, right?

[Jayefuu]

"  * A camera. Any DSLR camera should work; point-n-shoots tend to have quite small lenses so may not work so well."

[scoochmaroo]

Very clever!

[Cartermarquis]

I really like this. I've played around with Bokeh filters a little, and came up with a similar system of interchangeable filters, but not as simple/easy to use as yours. Heres my most recent one.  I didnt make the star quite small enough.