Bokeh Altering – Another Little Experiment

2 posts in one day!

This one has photos too.

Whilst doing a quick google search for “bokeh lights” in a hunt for some inspiration for some digital artwork I want to produce I came across a technique or phenomenon which goes by various phrases, but the term “Bokeh Altering” seems to sum it up best.

I won’t bore you all with the technical details about bokeh, but a brief description would be that it is a term derived from the Japanese word for “blur” (please don’t quote me on translations but it seems to be a generally accepted derivation). In photography it is used to describe the characteristic of the out of focus part of any photograph. Wide aperture lenses produce more aesthetically pleasing blurring when compared to standard lenses due to the nature of their construction. Again leaving out the details, alteration of this quality can lead to some really interesting results. The best thing about this is that it is really simple to produce, seriously, Blue Peter wouldn’t even have to bother with a “here’s one I made earlier”!

So for this little experiment I am attempting to alter the most easily recognisable characteristic of Bokeh. You’ll have seen it if you have ever watched a sappy movie where some star-crossed lovers are walking down a street at night, the camera cuts to a close up and the scene behind them is thrown into a glorious blur of night sky and soft circles of lights coming from  the street lights, passing cars and/or Christmas twinkly lights.

This blurring of these small light sources into perfectly round soft circles is what I am looking to alter…

You can literally chose any shape you like and as long you can cut it out of a piece of card you can do it.

For starters you will need a suitable lens. From what I have read the wider the aperture the better, for reasons that are a little technical and I will spare you all the details.  My lens of choice is the Nikon 50mm, F.1.8. It cost me about £75 on ebay brand new and it is still one of my favourite lenses!

I attached the lens to my Nikon D7000, as it was going to be a low light shot and the high ISO capabilities of this camera put my little old D80 to shame.  I could have used the D80 and mounted on a tripod to allow longer exposure time and get the same shot but I love shooting on my D7000 and using it handheld in this situation was just easier.

OK, to the pictures!

All you have to do is create a lens cap out of card that will fit over the lens and cut the desired shape into middle, the size of the hole is debatable but roughly l.5cm across seems to work quite well.

My D7000 with 50mm f/1.8 lens, capped with my star shaped bokeh altering cap

First shot…

Just to set the scene I took this shot without the star cap. I’ve taken this shot on numerous days and nights and even had a couple published on the Manchester Evening News website. Tonight has been a cloudy, drizzling rain sort of night so I quite surprised how nice this turned out.

Setting the scene, the skyline view from my balcony, in focus, with no bokeh altering cap,

Second Shot…

The control. Again not using the star cap, this shot is to show the natural bokeh effect created by forcing the lens out of focus.

Shot 2, skyline out of focus with no bokeh altering cap.

As you can see, the points of light in the photo have been blurred into creamy soft circles. This particular shot was taken by manually focussing the lens to about halfway between the infinity setting and the closest possible setting. I took one shot with the lens focussed at it’s minimum bit it was so fantastically blurred, all the circles merged together, which would not illustrate the point as clearly.

Third shot, the big finale…

OK, with the lens manually focussed the same as before, I placed the lens cap over the front of the lens and shot the exact same scene…. here it comes…

Skyline shot with bokeh altering star shaped lens cap.

Ta da! Voila! There you go! As simple as that. As you can see, all of those lovely soft circles have been “magically” transformed into stars!

I can’t wait to get out and experiment a little more with this. I’d like to play around a little bit with some foreground detail in focus and some off camera flash effects. The possibilities, as they say, are endless!

For those who enjoyed this brief experiment and would like to know more  of the details of why this occurs you can either google the term “Bokeh” or “Bokeh Adjustment” and read to your heart’s content. Alternatively you can message me and we can have an in depth “geek-out” about the subject!

So as it is now midnight and a certain someone has fallen asleep on the couch I’d better sign off.




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