Minimising depth of field with a compact camera

April 13, 2009 9:19 AM

How can I minimise the apparent depth-of-field (i.e. maximise the blurriness of the background) of photos using a compact camera?

I know I need to zoom in, and get as close to the subject and far from the background as possible. Is there anything else I can do? For example, will forcing ISO settings help? Would using the camera's 'Portrait' mode (or any other mode) affect depth-of-field (experimentation suggests not). The camera is a recent Canon Ixus/Elph.

posted by beniamino to technology (10 comments total)

I find Macro mode (usually a flower icon used for focusing on objects up close) can help achieve a blurry background.
posted by simplethings at 9:24 AM on April 13

In my experience, you can't - or at least not to the point where you'd actually notice. Depth of Field is mostly a function of the aperture size, and most compact cameras only have, at most, two.

When I needed shallow DOF for a recent picture from my point-and-shoot, I ended up just using Photoshop's Lens Blur filter. It's not ideal at all, but it did the trick, especially as the final picture was printed only about twice as big as a postage stamp.
posted by niles at 9:25 AM on April 13

Get in close is pretty much the best you can do. Most of the Ixuses/Elphs (Ixi/elves?) do have a couple stops of range of aperture. Portrait mode does indeed favor a wide aperture to maximize background blur.
posted by aubilenon at 9:38 AM on April 13

It won't make much difference, but keeping the ISO as low as possible will force the camera to use its widest aperture.
posted by diogenes at 9:53 AM on April 13

I use online software like Tilt Shift Maker.
posted by furtive at 10:07 AM on April 13 [2 favorites]

Zoom out, not in. Zooming in narrows the aperture, you want it wide open. If your camera has an aperture-priority mode, set it to the smallest f-stop number you can (ie widest aperture).
posted by -harlequin- at 12:29 PM on April 13

I think a Canon Elph will have both a macro mode and aperture-priority [A] mode.
posted by -harlequin- at 12:32 PM on April 13

You basically can't. Using your lens zoomed out as far as possible will be your best bet.

basically small sensor size=everything in focus all the time. That's why we have large sensor DSLRs and medium format digital cameras.
posted by sully75 at 12:33 PM on April 13

Depth of field (DoF) is affected by focal length, aperture and point of focus. Longer focal length and larger aperture (smaller number) decrease DoF. The closer your point of focus is the shorter your DoF will be as well. This is why you can shoot a landscape scene with a 50mm @ f/2.8 (on a 35mm camera) and still have everything be in focus, and why the same 50mm @ f/2.8 at close range will give you a sliver of DoF.

So, get your subject in close, zoom the lens and set the aperture as wide as it can go. That said, that won't work that well.

Don't use a photoshop filter, it takes a lot of work to get a 'sort of' good effect. Honestly, 99% of the time it'll look like a loser with a filter is screwing with their pics. Instead, find uncluttered backgrounds to shoot against. Accept the technical limitations of your camera and embrace them. Work around them through composition and thought-out shots instead of a filter.
posted by jedrek at 2:31 PM on April 13 [2 favorites]

As others have said:

1. zoom in (telephoto)
2. largest aperture setting (i.e. smallest X where the aperture is f/X)

Unfortunately, on most compact cameras these two instructions are mutually incompatible, as the lenses tend to have a smaller aperture at the telephoto end. Also, the small sensor vastly reduces your opportunity to get shallow depth of field. Two further thoughts:

1. When I used a compact camera, I wondered about the possibility of focusing so that the subject was at the very back of the in-focus depth - i.e. deliberately focusing in front of the subject, but not so much that the subject is unacceptably sharp. I think this should result in a more blurred background that putting the subject bang in the middle of the in-focus zone.

2. I've been experimenting with off-camera flash recently, and it's occurred to me that a good replacement for shallow depth of field (when you're working with a camera that doesn't allow it) is using a flash to overpower the ambient light and make the background dark (described e.g. here). That would give you not a similar effect, but maybe a similar result, in that it would focus (ha!) the viewer's attention on the subject/foreground.
posted by primer_dimer at 10:06 AM on April 14