I love photos like this: sharp object in foreground, blurred background. If you regularly view my blog posts, you’ll have noticed a few of them (and thank you for your visits!). But I freely admit I can’t be bothered to figure out the technicalities of taking them. I use a combination of zoom and focus area size to compose my shots. I set the ISO, colour balance, f stop and shutter speed manually, but don’t think about what’s happening beyond that. All of these photos were shot at 1/400 sec, F2.8, ISO 100.
But Jude’s assignment this week got me looking more closely at this selection of photos, and I did notice that the focal length corresponds to the amount of blur. “Lens focal length tells us the angle of view—how much of the scene will be captured—and the magnification—how large individual elements will be. The longer the focal length, the narrower the angle of view and the higher the magnification. The shorter the focal length, the wider the angle of view and the lower the magnification.” (source)
So I’ve presented these photos in order of longest to shortest focal length. The photo above and this one below have the same long focal length (most shallow depth of field) and extreme blurring of background.
The photos were all taken at Hamilton Island last July. Despite large signs stuck to the balcony doors saying “do not feed the cockatoos!!” the people beside me did just that.
This last photo has the shortest focal length (longest depth of field), and while the trees on the hill are certainly not in focus, they are much less blurred than in photos with longer focal lengths. The balconies are definitely much sharper.