Before we delve into that subject that seems to be the source of considerable
perplexity among even some very experienced photographers, a warning.
Beware of that newfangled information source called the Wide World Internet or
something like that. There are many web sites that purport to be expert
sources of information that are in fact pages filled with text and photos who's
main intent is to sell advertising! In doing my research to see what
others have said on this subject, I found two of the first three sites I visited
had depth of field (DOF) information that was dead wrong. It was, as many
experienced photographers will have already guessed, that old chestnut that
"Wide angle lenses have greater depth of field than telephoto lenses." Or,
the shorter the lens, the greater the depth of field. Dead wrong. So
let's get a few things straight first. Armed with the information below,
you'll changed DOF Mystery into DOF Mastery.
First, as Benny Hill would say, "What's this thing called, love?" In order
to understand DOF, we need some kind of definition. It's basically defined
as the area in the photo that appears sharp. Manufacturers have come up
with exact figures based on the Circles of Confusion (COF) size and how many
lines per millimeter appear sharp. But in practical terms, and since DOF
scales on camera lenses are practically nonexistent nowadays, you can use you
your eyeball, your knowledge, and experience to determine what will remain
sharp, and what will appear out of focus. For exacting work there are
tables you can use and even software you can download that will give you the
specs you need. Landscape photographers looking for maximum depth by using
hyperfocal distance should have this information. With all that in mind,
let's separate fact from fiction and see how we can use this information in
practical usage. Since I'm a portrait photographer, we'll see how to use
this information while doing portraits.
TRUE: The smaller the f/stop, the greater the depth of field.
FALSE: Shorter lenses have greater depth of field than longer lenses.
TRUE: Image size, not lens length, is a factor in depth of field.
The larger the image size, the less the depth of field.
TRUE: Depth of field extends about 1/3rd in front and 2/3rds behind the
point of focus, or twice as much behind as in front.
FALSE: To change perspective, change lenses.
There, got all that? And since we're talking portraits here, let's look at the
'typical' portrait. It's usually done with a long lens and a wide to
moderate f/stop (f/1.8 to f/5.6). Why? Because we usually want our
subject sharp, our background 'soft', a narrow angle of view, and a comfortable
working distance from our subject. People don't like lenses shoved in
their faces. Of course, I use lenses from 17mm to 300mm for
portraits. But that's another story.
Earn $200+ Per Day Taking Simple Photos In Your Local Area:
http://www.ptgjob.tk/
|
Having problems with message search?
Fill out this form to ensure your group is one of the first to be migrated to the new message search system.
Offline 
Send Email
