Monday, 12 March 2012

Canon camera AV mode - blurry background

Bokeh or the art of a blurry background
OK there are plenty of tutorials, articles and even Flikr groups dedicated to something called “Bokeh”. Now I could write a blog post everyday for a month about all the effects and equipment use to create different Bokeh, but I'll refrain. I am going to concentrate on taking photographs where the background is blurry, as we'd like the child to be in focus and infact in these photographs we'd like just the child to be in focus.

This can be handy when there's something in the background that could distract from the subject of the photo, or perhaps the background isn't very attractive. We'll cover how to blur the background artificially when we look at photo modification applications.

It's not your camera that counts...
When you bought your DSLR camera (Canon) it came with a bag, a strap and a lens. For 80% of the shots you want to take with your camera this lens is perfect, for really blurry background shots this lens isn't very good.

This is because the blurry effect is due to the lens aperture, or quite simply how big I can make the shutter aperture in the lens when I take the picture. In short the lens attached to your camera is a tube of glass lenses with a black circular shutter at one end (like the round twisty thing you see in the James Bond movie posters). Now this shutter opens when you take the photo – and depending on how easy it is for the light to reach the photo depends on how detailed the photo is.
I've lost you. OK.

Small aperture – Lots of focus.
Large aperture – Lots of blur.

Aperture is measured in F on your camera but is a result of your lens, turn your camera to AV mode and twist the adjustment dial to it's lowest setting to see your lowest F value. Alternatively look at the side of your lens – there are some numbers – 80-150 f5.6. << It tells you it's lowest f value.

For those 'professional' shots where only the lovely eyelash of the child or one side of the face is in focus then you need a lens that lets you reach an aperture of about 1.8. However the shots in this blog were taken with a lens aperture of 2.8.

Actually taking the photograph
So you have invested in a lens that gives you an aperture of 2.8 or less. You've selected AV mode and you're ready to go!

  1. Don't panic if you are looking through the view finder and it doesn't look all blurry in the background. The viewfinder can't always show you the effect of the low aperture setting – concentrate on the bit of the photo that you do want to be in focus.

  2. Use autofocus! Change your focusing mode to a single point if you are doing a close up head portrait shot or multiple points if you are taking a photo of the whole little one.

  3. If your shutter speed is 1/500 or more (1/250) then your shot will be perfect exposure (not to dark or light).

  4. If your shutter speed is 1/2500 then your shot will be over exposed and you need to drop the f setting to a few increments until it's 1/500.

Take lots of shots! One is bound to be the one you want.

Head shots 

I had about 0.2 milliseconds before the baby took this flower out of her hair. I'd not prepared the shot and we were sat on barstools 3ft up.
So while her face is in focus, nothing else is!

Thankfully CBeebies provided a distraction and I had time to focus on her eyelashes to take this shot. We were still on the bar stools!

Body shots 
This photo, my little blonde force of nature was running about on the green near our house. She's mostly in focus!

The photo to the right was taken in bright light – I didn't notice the shutter speed was 1/2500 in the first shots hence the over exposure).   

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