Design & colour
Equivalent shutter exposure
Keep a relative exposure while changing aperture and ISO.
A clear answer. Here’s how.
New shutter seconds = old seconds × (new f-number/old f-number)² × (old ISO/new ISO). Reports the required shutter duration and changes in stops. Assumes a fixed scene and ideal relative exposure response; depth of field, motion blur, noise and lens transmission can still change.
See a worked example
Worked example
A fixed demonstration, separate from the values you enter above.
- Original aperture f-number
- 4
- Shutter time in seconds (e.g. 1/125)
- 1/125
- Original ISO
- 100
- New aperture f-number
- 8
- New ISO
- 200
Example result
- Required shutter duration (seconds)
- 0.016
- Shutter time multiplier
- 2
- Aperture reduction (stops)
- 2
- ISO increase (stops)
- 1