If you imagine a diagram with the object uou're shooting on the left, The lens in the middle and the image created on the right.
O I
B M
J-----------------------------------LENS----------------------------------------- A
E G
C E
T
DEPTH OF FIELD DEPTH OF FOCUS
then:
Depth of field is how much the object can move nearer or farther from the lens and "Stay sharp" and Depth of focus is how much the image plane can move and "Stay sharp"
Of course there is only one PLANE of sharpness and the image becomes fuzzy anywhere else, but this "DEPTH" refers to an acceptable degree of sharpness.
(The basis for this is how big the diameter of a "POINT can be before it becomes a blurry disc.)
Depth of focus refers to the IMAGE side of the diagram and depth of field refers to the OBJECT side of the diagram. They are directly related to each other.
In any "Normal" camera (other than a view camera) you can not move the film plane so you don't have to worry about depth of focus.
In an enlarger the negative is the object and the paper is in the image plane. Depth of field describes how much you can move the negative carrier and depth of focus describes how much you can move the easel it is a concern when paper curls or the baseboard is not set up correctly
Elson Elizaga <elson615943@xxxxxxxxx> wrote:
Website remains confusing, primarily because a vague term is defined by vague terms or phrases:
"The depth of field, Dob is the range of distance [vague] along the optical axis [vague] in which the specimen [vague] can move without the image [image of the specimen? what is the specimen?] apppearing to lose sharpness. This [the specimen or the term 'depth of field'?] obviously depends on the resolution of the microscope."
I'm sure I'm missing something by my failure to completely comprehend the difference between depth of field and depth of focus, but several introductions to photography just use the phrase "depth of field", even though it could mean "depth of focus". I've tried to simply the problem by using the phrase "the space where everything is visually sharp" when I talk with layment. But, of course, I'm sure many technicians would object and would ask me, "You mean depth of field or depth of focus?"
howard <home@xxxxxxxxxxxxxxxxx> wrote:
Reference this - found by Googling
http://www.matter.org.uk/tem/depth_of_field.htm
seems to confirm my comment.
Howard
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Herschel Mair
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Higher College of Technology
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