|
Format, Viewing Size, Viewing Distance Independent Background Blur Metric
In reply to clengman,
6 months ago
|
clengman wrote:
... The maximum blur disk diameter depends on the absolute aperture of the lens and the subject distance and is most usefully (I think) expressed as a percentage of the frame height. This will tell you how blurred the background looks.I decided to try ditching this messy Hyperfocal Distance and Depth of Field stuff altogether, and used Merklinger's "Object Field" model in order to derive a mathematical identity that states the percentage of the total image-frame diagonal dimension that the blur-disk (Merklinger's "Disk of Confusion") represents (along the lines of what you are describing above).
B = ( (100) / ( (F)(H) ) ) x ( ( (L)/(D) )^(2) ) x ( Df - D ) / ( 1 + (M)/(P) )
where:
B is the percentage of the image-frame diagonal that the blur-disk represents;
F is F-Number;
H is the diagonal dimension of the image-sensor;
L is the Focal Length (when focused at infinity);
D is the Camera (front nodal-plane) to Subject (plane-of focus) Distance;
Df is the Camera (front nodal-plane) to Background Subject Matter Distance;
M is the Image Magnification;
P is the Pupillary Magnification.
In most situations, M is close to zero, so even if P is less than one (as in the case of a telephoto lens-system), the divisor of ( 1 + (M)/(P) ) will have a value that is close to one, so:
B ~ ( (100) / ( (F)(H) ) ) x ( ( (L)/(D) )^(2) ) x ( Df - D )
So, there you go, my friend. Number-crunch away. Last one in the pool is a "rotten egg" ...
| Post (hide subjects) | Posted by | When | |
|---|---|---|---|
| 6 months ago | |||
| 6 months ago | 6 | ||
| 6 months ago | 8 | ||
| 6 months ago | 4 | ||
| 6 months ago | |||
| 6 months ago | 2 | ||
| 6 months ago | |||
| 6 months ago | 2 | ||
| 6 months ago | |||
| 6 months ago | |||
| 6 months ago | 3 | ||
| 6 months ago | 1 | ||
| 6 months ago | |||
| 6 months ago | 3 | ||
| 6 months ago | 1 | ||
| 6 months ago | |||
| 6 months ago | 1 | ||
| 6 months ago | |||
| 6 months ago | |||
| 6 months ago | 1 | ||
| 6 months ago | |||
| 6 months ago | |||
| 6 months ago | 1 | ||
| 6 months ago | |||
| 6 months ago | 1 | ||
| 6 months ago | |||
| 6 months ago | |||
| 6 months ago | |||
| 6 months ago | |||
| 6 months ago | |||
| 6 months ago | |||
| 6 months ago | |||
| 6 months ago | |||
| 6 months ago | |||
| 6 months ago | 1 | ||
| 6 months ago | |||
| 6 months ago | |||
| 6 months ago | |||
| 6 months ago | 1 | ||
| 6 months ago | |||
| 6 months ago | |||
| 6 months ago | |||
| 6 months ago | 1 | ||
| 6 months ago | |||
| 6 months ago | 1 | ||
| 6 months ago | |||
| 6 months ago | 2 | ||
| 6 months ago | 1 | ||
| 6 months ago | |||
| 6 months ago | |||
| 6 months ago | 1 | ||
| 6 months ago | |||
| 6 months ago | |||
| 6 months ago | 1 | ||
| 6 months ago | 1 | ||
| 6 months ago | |||
| 6 months ago | |||
| 6 months ago | 1 | ||
| 6 months ago | |||
| 6 months ago | |||
| 6 months ago | 2 | ||
| 6 months ago | |||
| 6 months ago | |||
| 6 months ago | |||
| 6 months ago | |||
| 6 months ago | 1 | ||
| 6 months ago | |||
| 6 months ago | 3 | ||
| 6 months ago | |||
| 6 months ago | |||
| 6 months ago | 2 | ||
| 6 months ago | |||
| 6 months ago | |||
| 6 months ago | |||
| 6 months ago | 6 | ||
| 6 months ago | |||
| 6 months ago | |||
| 6 months ago | 2 | ||
| 6 months ago | 2 | ||
| 6 months ago | 2 | ||
| 6 months ago | 2 | ||
| 6 months ago | |||
| 6 months ago | |||
| 6 months ago | 1 | ||
| 6 months ago | |||
| 6 months ago | |||
| 6 months ago | |||
| 6 months ago | |||
| 6 months ago | |||
| 6 months ago | |||
| 6 months ago | |||
| 6 months ago | |||
| 6 months ago | |||
| 6 months ago | |||
| 6 months ago | |||
| 6 months ago | |||
| 6 months ago | |||
| 6 months ago | |||
| 6 months ago | 1 | ||
| 6 months ago | |||
| 6 months ago | 1 | ||
| 6 months ago | |||
| 6 months ago | |||
| 6 months ago | |||
| 6 months ago | |||
| 6 months ago | |||
| 6 months ago | |||
| 6 months ago | 1 | ||
| 6 months ago | |||
| 6 months ago | |||
| 6 months ago | |||
| 6 months ago | |||
| 6 months ago | |||
| 6 months ago | 1 | ||
| 6 months ago | 1 | ||
| 6 months ago | |||
| 6 months ago | |||
| 6 months ago | |||
| 6 months ago | |||
| 6 months ago | |||
| 6 months ago | |||
| 6 months ago | |||
| 6 months ago | 1 | ||
| 6 months ago | |||
| 6 months ago | |||
| 6 months ago | |||
| 6 months ago | |||
| 6 months ago | |||
| 6 months ago | |||
| 6 months ago | |||
| 6 months ago | |||
| 6 months ago | |||
| 6 months ago | |||
| 6 months ago | |||
| 6 months ago | |||
| 6 months ago | |||
| 6 months ago | |||
| 6 months ago | 1 | ||
| 6 months ago | |||
| 6 months ago | |||
| 6 months ago | |||
| 6 months ago | |||
| 6 months ago | |||
| 6 months ago | |||
| 6 months ago | |||
| 6 months ago | 1 |