Superzooms are very tempting, but there's a downside
September 24, 2009
At the longest focal length, zoom lenses on compact cameras produce darker images, especially when shooting with your flash.
Today's Fix the Pix photos were shot with a Casio Exilim EX-FS10.
It's very tempting to zoom your camera all the way so you can make distant subjects appear close. This is especially true if you own a superzoom camera (that's a camera with a lens whose longest focal length is at least ten times its shortest focal length; ie, 28-280mm.) When your compact camera’s zoom lens is at its longest focal length, it captures less light, and that’s where problems arise.
The quick technical explanation is that as lenses zoom out, their effective apertures get smaller, and this means less light hits the sensor. The camera compensates by either boosting ISO or turning on the flash. But because the lens lets in less light, the flash is less effective. (It also means that without flash, it's likely that your images will suffer from camera shake.)
Long zoom fail (right): Shot with 10x zoom at full extension from about 15 feet away, anemic flash plus long lens with narrow f/5.6 aperture translates into a picture that’s too dark.
At their longest focal lengths, lenses can also magnify optical imperfections within the lens, so even if you hold the camera perfectly steady, the image quality may not be as sharp as it is when shooting at a wide-angle setting.
A little better: By boosting the IS0, in this case from 100 to 800 (which cameras will do automatically when in “auto ISO” mode, if they have it), I was able to get a somewhat lighter shot but it’s still going to print dark. Yes, I could fix this in Photoshop, but I’d rather get a perfect exposure out of the camera in the first place and save time later. Wouldn't you?
My recommendation: Don't use the entire zoom range. If you have a 10x zoom lens, only zoom 6-7x. If possible, make up for the rest of the range by "zooming with your feet." In other words, move closer to your subject whenever you can. Do this and you'll have a better chance of getting well-exposed flash people pix.
Pix fix: I zoomed out slightly and took a few steps closer, photographing her from around 8 feet away with the zoom lens at a more moderate 6x. This is a good, printable exposure with no Photoshop changes needed.