What good is the EXIF data that is stored
with your 'digital negative', that is, your photograph's
image file? Photographer, Chris Roberts, will explain.
How EXIF Data Can Improve Your
Photography
Every digital image has a secret identity.
The big difference between your digital photos and a
CIA operative is that it's pretty easy to discover the
secret identity of a digital photo.
This not-so-secret information is called EXIF data,
and it's encoded in every photo that you take with your
digital camera. Think of it like a barcode on a package:
in the same way that the barcode uniquely identifies
the product, EXIF data uniquely identifies an image.
But how can EXIF data improve your photography? Let's
find out.
Common Camera Settings
There are two principal actors in the photos that you
take: aperture and shutter speed.
Aperture is a measure of how wide your lens opens, and
shutter speed is how long your camera's shutter stays
open to expose the digital sensor to light.
All digital SLR cameras and some compacts let you manually
control aperture and shutter speed.
The best way to learn what impact these two features
have on your photos is to tweak the settings and see
the effects.
With film, there is no way to tell what the aperture
and shutter speed are set to for any given image. If
you want to keep track, you have to write down the numbers
on a notepad for every shot you take.
Not exactly convenient.
On a digital camera, the EXIF data takes care of this
for you.
Permanent Setting Storage
Every time you take a photo with a digital camera, the
camera automatically saves the aperture, shutter speed,
and a variety of other settings.
This EXIF data is permanently attached to the photo,
so even when you transfer it from camera to computer
the data is not lost.
Once you open the photo in your image editor of choice,
you can choose to view this EXIF data any time you want
(even a year later).
Here's why this is such a powerful learning tool: you
can easily review all of your camera settings for every
photo you take.
Learning From EXIF
Example one: you take what you think is a great photo
of your daughter playing in the living room. You check
the photo on the computer and the entire shot is blurry.
Why? Check the EXIF data and note the shutter speed.
It was probably too slow to get a clear shot of your
daughter in motion.
Example two: you take a photo of your friend in front
of a fountain. It looks like the water is spouting from
the top of his head.
The EXIF data shows that your aperture was set to f/11.
This aperture ensures that both the friend and the fountain
are in clear focus. A different aperture setting would
have kept your friend in focus but blurred the background.
While you can learn a lot from mistakes like these,
pay special attention to photos that are successful.
Check the EXIF data often for photos that you love,
and you might find some camera settings in common.
In the future, you can manually set your camera to your "favorite" settings
and capture more photos that are keepers.
There you have it.
EXIF data just helped to improve your photography.
Chris Roberts dispenses practical plain-English
advice and information about digital SLR cameras at
the Digital SLR Guide. His
5-week ecourse in digital SLR technique helps beginners get the most out of their
digital SLR cameras.
