Datasheet

10
CHAPTER 1 : BEFORE YOU SHOOT ■
Note: What exactly is “noise” in a digital photo? All sensors have some level of electronic
noise caused by the random motion of electrons in the silicon. In high light, the ratio of image
electrons to noise electrons is high, and the noise is hardly seen. In low light, the ratio of
image electrons to noise electrons is low and when the image signal must be amplified to cre-
ate a useful image, the amplification affects both the image and noise. This makes the noise
very visible in such images. The film equivalent of electronic noise is grain. Just as with film,
where going to higher speed films produces more grain, with digital cameras, as you increase
the ISO sensitivity, you will see more electronic noise in your images.
• Some mechanical shutters provide faster synch speeds when used with electronic
flash. This can be important if you are trying to balance flash with bright daylight.
Bottom line: Just about everything you know about film cameras and shutter speeds will
apply to shooting digital.
Metadata
One of the biggest differences between film cameras and digital cameras is the amount of
metadata that can be generated. Metadata is information encoded onto the film or into
the digital file. Some film cameras embed the date and time a picture was taken, and with
a special data back you might be able to encode some other type-based information. This
is nothing compared to the data that is typically encoded by a digital camera.
Digital camera manufacturers have standardized the way this metadata is saved
into a format called Exchangeable Image File, or EXIF for short. To read this EXIF
data, you’ll need imaging software such as Photoshop or Photoshop Elements, or the
imaging software that often comes with a digital camera.
Not only can you use EXIF data to see what type of digital camera was used,
but you can also see the date, f-stop, shutter speed, ISO, and whether a flash was on or
off. Some of the higher-end prosumer and professional cameras even allow you to hook
up a global positioning system (GPS) to your camera so you can encode in the EXIF
metadata the exact spot in the world where you shot a particular image.
Metadata can be used by printing software to determine print resolution. It can
help you organize your digital images and even make you a better photographer by giv-
ing you a handy reference to your camera settings.
Beyond Film
There is a point where the electronic and chemical worlds completely diverge. For
example, most digital cameras are equipped with an LCD screen that provides near-
instant image playback. This may sound like a small thing, but in reality preview ability
has important significance. As you’ll see throughout the book, LCD previews can be
used in a variety of ways, from displaying technical data on the quality of an image to
precise framing, to icebreakers that help your subjects relax as you photograph them.
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