In outdoor portraits, we love shallow depth of field. We love to see the background nicely out of focus so that our subjects stand out better. In fact, we are easily convinced that we need to pay a lot of money for very bright lenses with big apertures so that we can get that beautiful shallow depth of field.
The truth is that you can do with an inexpensive zoom lens — even the second lens that came with your camera kit can get it done well. Many kits come with a 55-200mm zoom, and you can also buy a 70-300mm lens for a couple of hundred dollars that’ll do a great job.
How can a cheap lens do this?
The reason this works is that depth of field is not only a function of a lens’s aperture. Yes, a big open aperture, like f/2.8, makes a shallower depth of field than f/11. But there are two more factors that affect it, too.
You can get a shallower depth of field with any lens (and any aperture) by focusing on a subject that is closer to your camera. You’ve already noticed this when you photograph close-ups of flowers. The background is always nice and blurry (which is one of the things that attracts everyone to flower photography — you look like a pro immediately!).
Zooming in also makes the background more out of focus. Even those inexpensive (relatively inexpensive, anyway) lenses that came in your kit can give you a good effect. Even better if you combine zooming in and focusing close. You don’t need the person’s whole body in the shot, so you can zoom in all the way and then walk closer to frame the shot. Treat your telephoto lens like it’s a long prime — keep it zoomed in and move your feet to frame — and you’ll get great results without spending a lot of dough.
This picture was shot at 213mm and f/5.1 on my Lumix G9. Now, this 100-400mm lens isn’t really cheap, but it’s not shooting at f/2.8 and it’s giving a great result. Try this with your longest lens and I think you’ll be hooked.
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