Bokeh Effects

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Background

Bokeh is an adaptation from a a Japanese word meaning blur. In photography this term is used to describe the quality of the areas in the picture which are not in focus” (Udi Tirosh. (2007). DIY Bokeh. Available: http://www.diyphotography.net/diy_create_your_own_bokeh/. Last accessed 1st Jan 2015.)

What consists of a pleasing bokeh is entirely subjective being entirely the opinion of the viewer. There is,  however, what is usually accepted as good practice, for example in portrait photography bokeh is used to make the subject stand out from the background, if part of the subject is also to be deliberately blurred the point of focus is generally the eye. Images where the eye is not sharp look distinctly odd.. To achieve the bokeh effect a wide aperture is required, the wider the aperture the more pronounced the effect. Hence prime lenses with wide apertures are best suited to achieving good results although the effect will be present to a degree in all lenses, how visible the effect will depend on a number of factors such as focal lenth of the lens, distance from subject, aperture and visible highlights in the background.

Bokeh is particularly visible when there are strong highlights present such as those generated by street or Christmas lights, a wide aperture lens focussed in front of the light source will naturally produce round bokeh. The two images below were produced by merely changing the focus of the lenses, i.e. they are of the same Christmas tree, with the same shutter and aperture settings taken from the same distance (1.5 metres) it is simply that in the second image the focus has been set to about a half a metre from the camera. They were taken on a Canon 5D MKIII with a 50mm lens at it’s maximum F1.4 aperture.

 

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It is also possible to determine the shape of the bokeh by placing a template with a cut out of the desired shape in front of the lens. Some variations below, the different colours are a result of the variously coloured light sources the different shapes by the template selected :

Sunburst

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Shoe

 

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Heart

 

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Preparation

Commercial bokeh templates are available but it’s fun and easy to make your own, there are many example tutorials on the internet. The templates I made were cut out of scraps of black background paper using some paper crafting punches that my wife happened to have. The only issue was that the punch couldn’t reach into what would be the centre of the lens so I needed a method to mount the resulting template. During the course of the shoot I also found a Christmas ornament with a heart shaped cut out and that worked well too.

As I wanted to be able to change the bokeh templates frequently I decided to make something more solid than paper for the holder, so I cut a plastic disc out of the back of an old DVD case, having first drilled a large hole in the centre and then stuck it to a stepping ring using insulation tape to make a light proof seal. I used the stepping ring in order to provide an easy and reliable means to mount the holder on the lens. The various templates were then simply attached to the front of the assembled holder with masking tape.

Holder

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Templates

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The finished bokeh template holder worked well, screwed directly to the front of my 50mm Lens. I used the Christmas tree as the background and intended to go into the Cricklade town to capture the Christmas lights currently on display however the weather was foul in Cricklade on Jan 1st so will postpone this until the weekend. To complete today’s shoot I decided to add some foreground interest to the purely light shapes. It was serendipitous  to have a shoe template as for another project had learned that one of our lecturers, Jen, crafts hand made shoes and so decided to introduce a shoe into the proceedings as thought it would amuse her.

With the camera mounted on a tripod I simply held the shoe at the half metre focus distance and lit the shoe from the side with a speedlite set to a very low power setting (1/64) as I didn’t want it to be obvious the Christmas tree was the background and keeping the lighting level low obscured it. I also used a voice activated lighting stand (my wife Karen :-)) to hold the flash to obtain the final image.

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 Exterior Shots.

With a cold clear night in prospect I went and captured some shots of the local town Christmas lights. Having determined a reasonable exposure with a few tests shots without the bokeh holder attached and then setting the camera to manual and I found the best way to compose images was to use the live view feature of the camera and manually alter the focus to see the effect. Both the focus distance and the physical distance of the camera to the light source had a dramatic impact on the resulting image.

Hight Street Lights

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I found more (personally) pleasing images could be made by using a tree that was decorated with lights shot from a relatively close distance – 3 or 4 metres – as the light source gave sharper results than general street scenes. An explanation of the multi-coloured effect is given below.

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Having obtained some nice bokeh images I decided to then apply some post processing to images using similar techniques to the recent smoke trails exercise.

bokeh_06__MG_5786_as_takenProcessing in camera raw, reducing exposure slightly decreasing blacks and increasing clarity gives the image above which still has some unwanted detail in the background, this was cleaned up in Photshop by painting over with a black brush to produce :

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To introduce more colour then 2 hue saturation layers were added with a red and green emphasis. With opacity set to about 70%  and then with a large brush painting out some areas allowed the various colours to show through. Where the masking overlaps in the hue/saturation levels the original image shows through, in other areas one or other of the hue/saturation colours is visible. Further colour adjustments can be made by adjusting the blending mode of the various layers.

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Click here for a gallery of all bokeh images.

This entry was posted in Digital Imaging, Location.

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