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p.2 #1 · p.2 #1 · Can someone explain the hyperfocal distance?!? | |
Alan321 wrote:
It was once a very common rule of thumb that DOF was split about 1/3 towards the camera and 2/3 away from the camera relative to the focus plane. In fact it was a very flawed rule. There are occasions when it applies but far more often the split is about 1/2 and 1/2 until you get to very large focus distances. Play with a DOF calculator to confirm this for yourself.
The DOF split is one of the poorest excuses of a Rule of Thumb as you can find! DOF can be 50:50 at very close distances, but it goes to 0.1:99.9 out at very far distances, and it is at 33:66 only at a single distance (as you can see from this table, which assumes a 100mm lens at f/4)
The CofC size assumed on most DOF calculators assumes human visual acuity which is poorer than the 20/20 standard which is the goal of the typical optometrist. IOW, most folks will perceive 'out of focus' at ranges where DOF calculators tell you are 'in focus'! This is one reason why seasoned veterans shooting fixed focal length lenses used the DOF scale marks which assume an f/stop one size LARGER than the shooting aperture...to compensate for poor assumptions of CofC perception.
The DOF calculators also assume viewing an 8x10 print from about 12" away...if you make a larger print and view it at the same 12" distance, the DOF calculation is rendered invalid!
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