Enter the T-Stop value and the lens transmission percentage into the calculator to determine the equivalent F-Stop value. This calculator helps in converting T-Stop, which accounts for light transmission efficiency, to the standard F-Stop used in photography.
T-Stop to F-Stop Formula
The following formula is used to convert a T-Stop value to an F-Stop value.
F-Stop = T-Stop * sqrt(Transmission / 100)
Variables:
- T-Stop is the T-Stop value of the lens.
- Transmission is the percentage of light that is transmitted through the lens.
- F-Stop is the equivalent F-Stop value.
To convert T-Stop to F-Stop, multiply the T-Stop value by the square root of the lens transmission percentage divided by 100.
What is T-Stop?
T-Stop, or Transmission Stop, is a measurement that indicates the actual amount of light that passes through a lens and reaches the camera sensor or film. Unlike F-Stop, which is a theoretical value based on the lens aperture size, T-Stop takes into account the light loss due to the lens glass and coatings. T-Stop provides a more accurate exposure measurement, which is especially useful in cinematography where consistent exposure is crucial across different lenses.
How to Calculate F-Stop from T-Stop?
The following steps outline how to calculate the F-Stop from a T-Stop value.
- First, determine the T-Stop value of the lens.
- Next, determine the lens transmission percentage.
- Use the formula F-Stop = T-Stop / sqrt(Transmission / 100).
- Finally, calculate the equivalent F-Stop value.
- After inserting the variables and calculating the result, check your answer with the calculator above.
Example Problem:
Use the following variables as an example problem to test your knowledge.
T-Stop value of the lens = 2.8
Lens transmission percentage = 90%
Using the formula, the equivalent F-Stop value is calculated as follows:
F-Stop = 2.8 / sqrt(90 / 100) = 2.8 / sqrt(0.9) ≈ 2.8 / 0.949 ≈ 2.95
Therefore, the equivalent F-Stop value is approximately 2.95.
