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How to Produce Background Blur

Posted by: rich | December 30, 2008 | 4 Comments |
What sometimes grabs our eye in a photo is the contrast in detail between one or more objects in a photo. This is commonly referred to as bokeh or background or foreground blur. There is that element in photography which we immediately recognize because this is exactly how we tend to see things naturally and when we see this in an image it grabs our attention. But how do we produce this most powerful photographic effect?

Old Hay Rake

There are more than one element involved in this. First and most importantly your subject should minimally be a pleasing-to-the-eye subject and better yet a strong one. Here we have a most unusual subject, an old steel wheel off a farm implement no longer used. Rusty, hardly even noticed in a run-down farm field most passers-by would not give it a second glance. It is just another worn down piece of junk from days gone by. But when photographed using bokeh, it commands 1st place attention. The fact that this is in B&W may help a bit more to some, but the primary ingredient is the subject placement in the lens, or the sensor’s field of view.

Can this be done with any camera? Well yes & no. The camera can capture this even if it is a consumer point & shoot pocket sized one, but the true effect is best captured using a Wide Zoom Lens and at the longest telephoto length. Say you are using a 17-40 zoom. The fact that it is fairly wide, 17mm coupled with it being in the longest length produces the very best bokeh possible. However in the above photo this can also be accomplished with a mid-range zoo as it was captured using a 70-200mm lens at an F-stop of 9 and a zoom length of 200. And further as I mentioned above this can involve the foreground or background blurred, in this particular case I have produced a blur in both. You see only a very tight range, for this subject, in the middle as pertains to it’s Depth of Field.

Pine Flowers

Now here is another using a consumer level point & shoot, a Canon PowerShot S2 IS, captured at an F stop of 3.5 and a focal length of only 21mm. Imagine how much more blurry this would have been if the camera was able to capture it at a longer length, or I had backed up more & then refocused on just the pine flowers. So you see this technique of creating bokeh can be a regular part of your shooting expertise by simply using a couple of factors.

under: Photos Tips & Tricks
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Responses -

awesome advice! Thank you :)

   By: 1stAngel on December 30, 2008
at 11:43 am

Hi Rich. Thanks for this explanation.

Shallow depth of field is achieved by either using a long focal length or a wide aperture. Most point-and-shoots won’t let you set the aperture but many of them have a portrait setting. The portrait setting is programmed to use the widest aperture possible given meter reading and zoom setting in order to throw anything behind or in front of the ’sitter’ out of focus. Maybe this helps, too. This is the setting I use on my Sony Cybershot T100.

Another favourite of mine is the super macro setting, which works at the widest angle of the lens only on this particular camera but as you can move as close as 5 cm on something you focus on, everything else is out of focus. With this particular setting the effect is strongest the closest you get to what you focus on.

Hope this helps.

   By: f2point4 on December 30, 2008
at 12:42 pm

Sorry, I forgot to say, I used the macro setting on the picture in my last entry: “freezing…”, just for illustration.

   By: f2point4 on December 30, 2008
at 12:45 pm

Yes thank you f2point4. Your added advice is appreciated.

   By: rich on December 30, 2008
at 8:13 pm

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