Calculate exposure compensation for bellows extension and extension tubes
In macro photography, extending the distance between the lens and the image sensor increases magnification, but it also reduces the light that reaches the sensor. This light loss must be compensated for to achieve proper exposure.
This calculator helps you determine the exact exposure compensation needed based on your bellows extension and lens focal length.
The bellows factor is calculated using the formula: (1 + Extension ÷ Focal Length)²
0.0 stops
Increase exposure by this amount to compensate for light loss from the bellows extension.
When using bellows or extension tubes for macro photography, you need to increase exposure to compensate for light loss. The amount of compensation depends on the ratio of extension to focal length.
| Magnification | Extension Ratio | Compensation |
|---|---|---|
| 1:2 | 0.5x | 1.5 stops |
| 1:1 | 1x | 2 stops |
| 2:1 | 2x | 3 stops |
Once you know the number of stops to compensate, you can:
The same principles apply whether you're using:
For extension tubes, add the combined length of all tubes to calculate total extension.
