Formulas for Object Size / Focal Length
Calculations
for Object Size
To calculate object size at a given distance:
Formula:
Example:
What height will an object be at 100ft from the lens
using a 50mm lens on a 2/3" camera?
(Note: Formula will work using feet or meters for the
variables)
Image Sizes
|
Format
|
1"
|
2/3"
|
1/2"
|
1/3"
|
1/4"
|
|
Height (mm) |
9.6 |
6.6 |
4.8 |
3.6 |
2.7 |
|
Width (mm) |
12.8 |
8.8 |
6.4 |
4.8 |
3.6 |
Metric Conversions
mm X 0.03937 = inch
m X 3.281 = feet
Calculation of
Focal Length
To calculate the focal length needed:
Formula:
Example:
What focal length is needed for an object be 20ft high
at a distance of 200 feet using a 2/3" camera?
(Note: Formula will work using feet or meters for the
variables)
Image Sizes
|
Format
|
1"
|
2/3"
|
1/2"
|
1/3"
|
1/4"
|
|
Height (mm) |
9.6 |
6.6 |
4.8 |
3.6 |
2.7 |
|
Width (mm) |
12.8 |
8.8 |
6.4 |
4.8 |
3.6 |
Metric Conversions
mm X 0.03937 = inch
m X 3.281 = feet
|
