Posts by tag: focus

Bokeh-O-Matic

Posted by Caz on Sunday, 23rd January 2011

What The Heck Is Bokeh Anyway?

In the last few years, bokeh has become a popular buzzword amongst photographers. Many folks are not really sure what it means, however. During 2008, I had a go at taking a picture to illustrate the meaning on Day #155. The definition is thus:

Bokeh n. a term for the subjective aesthetic quality of out-of-focus areas of a photographic image. [Jap. bokeh, blur]

That Still Doesn’t Mean Much!

OK, here’s another way to show it. The image below has a very narrow depth of field. The beads at the bottom are in focus but as you go further towards the top, the image blurs – that’s bokeh.

Shiny beads with receding focus

Shiny beads with receding focus

Alternatively, you could go for a shot where everything is deliberately out of focus:

Bokeh, bokeh, everywhere

Bokeh, bokeh, everywhere

OK, So Now What?

You’ll see shots exhibiting bokeh all over the place on Flickr. But sometimes, you may notice ones which not only have the round or 5/7-sided blurred shapes, but also other more unexpected variants such as hearts or stars. How to go about getting a shot like this? Well, I did some googling over Christmas and found a handy tutorial, the principles of which I’ll explain here.

The Bokeh-O-Matic

I decided to make myself a little gadget which would help me get custom bokeh whenever I wanted it. Enter the Bokeh-O-Matic:

Custom Bokeh Masks

Custom Bokeh Masks

Main mask fits on the front of the 60mm lens

Main mask fits on the front of the 60mm lens

In the centre of the above image is a circle of black cartridge paper, just large enough to fit snugly into the filter threads and cover the front of my 60mm f/2.8 macro lens (and my trusty old 50mm f/1.8 too) – see left. Bokeh works best when you have a lens with a large maximum aperture.

I covered this mask with sellotape, cutting out the central square, and put two “ears” on the sides so I could easily grab it from the front of the lens when finished with.

On it’s own, this won’t give you very much apart from a bad case of vignetting.

Custom bokeh mask added

Custom bokeh mask added

However, apply one of the smaller custom masks to the front and stick it on with sellotape or just hold it in place and rotate to see how the bokeh pattern changes your image (see right).

For this lens, a mask hole of no more than about 5mm at the widest point seemed to produce the best results. You could try your own experiments with the size of custom mask.

Applying this combo to the front of your lens will of course reduce the amount of light getting to the sensor quite dramatically, and longer shutter speeds will be required, so beware of camera shake (a different kettle of fish to artistic focus blur).

Show Me Some Pretty Pictures!

Here is a selection of images taken with various masks in front of the lens:

One large triangle

One large triangle

Crosses

Crosses

How About Clubs?

How About Clubs?

Christmas bells

Christmas bells

Six tiny triangles

Six tiny triangles

I see stars!

I see stars!

Have A Go

Have a go yourself at creating your own bokeh-o-matic for fun backgrounds. My favourite from today’s shoot was the one with hearts, which I chose for Day #1119.