Canon 7D Tips – Magnification plus F-stop equals Blurred Background

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Take a look at the above photos.   Both photos were shot with my Canon 7D and the Canon 100mm-400mm L lens at 200mm and 1/350 shutter speed.  The only difference was the f-stop.  Even an f/5.0 f-stop can produce a great blurred background (bokeh) when the lens magnification is high enough.


So what about an f/2.8 f-stop?  Well, an f/2.8 alone will not produce a significantly blurred background. Take a look at the above photos.  Both photos were taken with the Canon 15-55mm EF-S lens at 55mm.  The background in the f/2.8 photo was blurred, but not as much as in the 200mm photo.  The background is simply too close to produce a significant blur even at f/2.8.

Spring flowers are just starting to bloom, so experiment with this simple formula:

magnification + wide open f-stop + distance = blurred background

You can produce a pleasant blurred background even with a f/5.0 f-stop when the magnification is high enough.  Now you might be asking, what would happen if you had a faster lens like the Canon 85mm f/1.2 L?  The wider f-stop would produce a smoother blurred background.  (Take a look at the bokeh comparison in my review of  Sigma’s 50mm f/1.4 lens.)  But, don’t let that stop you from being creative with the lenses that you already have.


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4 Replies to “Canon 7D Tips – Magnification plus F-stop equals Blurred Background”

  1. another factor to take into acount is the distance from your subject. You don’t need a tele-zoom lens to create ‘bokeh’, if you just move your 18-55 closer to the subject, the background will start to blur more too.

  2. Yes! The 7D is a DSLR which just happens to also shoot video. You can use the full Manual mode or the AV Aperture Priority mode to control the f-stop for shooting either video or still photos. Just flip the switch to either Live View or Movie Shooting.

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