Wigwam Jones
Caesar non supra grammati
Sorry, this bugged me. Thread got closed and I was not allowed to respond to an obviously incorrect statement because I was rude.
So, I won't be rude in this thread.
Depth of Field, which is the distance that a given photograph is 'in acceptable focus' is NOT a function of the focal length only.
http://www.dofmaster.com/dofjs.html
Focal length, f/stop, and size of sensor (or film size) and distance to the subject combine to make depth of field.
If you go to the link above and put in your typical digicam, which has a sensor size of 1/2.5 of an inch (very small), you will note that your typical depth of field for a subject 10 feet away, assuming a 50mm (equivalent) lens (would be 6.3 mm in digicam terms):
Subject distance 10 ft
Depth of field
Near limit 6.16 ft
Far limit 26.6 ft
Total 20.4 ft
In front of subject 3.8 ft (19%)
Behind subject 16.6 ft (81%)
Now, take 35mm film and a 50mm lens, same f/stop, same distance:
Subject distance 10 ft
Depth of field
Near limit 9.08 ft
Far limit 11.1 ft
Total 2.06 ft
In front of subject 0.92 ft (45%)
Behind subject 1.13 ft (55%)
The difference is 20 feet of focus in total versus 2 feet of focus. This means you will get a much slimmer DOF for a given focal length, for a given distance, for a given f/stop, if you have a larger sensor (or film size).
It is incorrect to state that a digicam can do the same DOF tricks that a 35mm film camera can. Not only can it not do them well, it can barely do them at all.
I mean no insult towards anyone. Things like this get on my nerves. Digicams are great, I love 'em, I use 'em. But they are hardly a replacement for a 35mm film camera, and until their sensor size is the same as a 35mm frame of film (some dSLR cameras have that) they will not be a suitable replacement. That's not opinion - simple, provable, fact. The math does not lie.
So, I won't be rude in this thread.
Depth of Field, which is the distance that a given photograph is 'in acceptable focus' is NOT a function of the focal length only.
http://www.dofmaster.com/dofjs.html
Focal length, f/stop, and size of sensor (or film size) and distance to the subject combine to make depth of field.
If you go to the link above and put in your typical digicam, which has a sensor size of 1/2.5 of an inch (very small), you will note that your typical depth of field for a subject 10 feet away, assuming a 50mm (equivalent) lens (would be 6.3 mm in digicam terms):
Subject distance 10 ft
Depth of field
Near limit 6.16 ft
Far limit 26.6 ft
Total 20.4 ft
In front of subject 3.8 ft (19%)
Behind subject 16.6 ft (81%)
Now, take 35mm film and a 50mm lens, same f/stop, same distance:
Subject distance 10 ft
Depth of field
Near limit 9.08 ft
Far limit 11.1 ft
Total 2.06 ft
In front of subject 0.92 ft (45%)
Behind subject 1.13 ft (55%)
The difference is 20 feet of focus in total versus 2 feet of focus. This means you will get a much slimmer DOF for a given focal length, for a given distance, for a given f/stop, if you have a larger sensor (or film size).
It is incorrect to state that a digicam can do the same DOF tricks that a 35mm film camera can. Not only can it not do them well, it can barely do them at all.
I mean no insult towards anyone. Things like this get on my nerves. Digicams are great, I love 'em, I use 'em. But they are hardly a replacement for a 35mm film camera, and until their sensor size is the same as a 35mm frame of film (some dSLR cameras have that) they will not be a suitable replacement. That's not opinion - simple, provable, fact. The math does not lie.
