An eclectic selection of technology with some cookery
Working out what factors of a lens / camera body govern the depth of field of an image.
Often know as a “F Number” in photograthry. Also the term “T number” is sometimes used in high end cinimatic lenses. To my understanding F numbers are calculated from the lenses design where “T” numbers are measured by sending light though a built lens. The latter being more accurite. For the purposes of the calcilation they will be used interchangeably.
The focal length of the lens, normall stated in “mm”. Commonly a 50mm lense is used with a 35mm film stills or “full frame” camera.
f not to be confised with the “F number”.
How far is the lense from the subject.
I’ll adopt the d/1500 calculation to simplify this.
Sensor Size | CoC |
---|---|
1” | 11μm |
4/3” | 15μm |
APS-C | 18μm |
35mm | 29μm |
DOC = (2 ( u 2) N c)/ ( f 2)
This suggests f focal length and Distance to subject have the largest effect as they are square factors
Doing some calculations on a spreadsheet agrees with the above statment, sensor size also has a noticable effect but not as much as you might think. Also having F Numbers on lenses and reffering to f for focal lenght is very confusing.