Star saturation
Protect highlight detail before the well fills.
Compare a measured peak electron rate with the camera well, gain and chosen exposure.
Purpose and method
What this calculator does
Will bright stars saturate in this exposure? Predict when a bright-star pixel reaches usable full well.
In words: Usable well capacity divided by peak electron rate sets the saturation time.
Change a value and the result updates immediately. Seeing, focus, guiding, filter choice and sub-pixel star position redistribute light, so validate the prediction with a representative test frame.
Working geometry
Pixel-well filling
A bright-star peak fills the finite pixel well until the reserved highlight headroom is reached.
Inputs
Sensor and bright-star measurement
Calculated now
Highlight headroom
- Usable well
- 32,000.00 e⁻
- Saturation-limited exposure
- 160.00 s
- Predicted peak electrons
- 24,000.00 e⁻
- Predicted peak ADU
- 48,000.00 ADU
- Well used
- 60.00 %
- Headroom status
- Available
Governing equation
In words: Peak electrons equal the measured peak electron rate multiplied by exposure time.
Show the working
The calculator applies the equation above to the values currently entered, without rounding until this display.
- Usable well
- 32,000.00 e⁻
- Saturation-limited exposure
- 160.00 s
- Predicted peak electrons
- 24,000.00 e⁻
- Predicted peak ADU
- 48,000.00 ADU
- Well used
- 60.00 %
- Headroom status
- Available
Seeing, focus, guiding, filter choice and sub-pixel star position redistribute light, so validate the prediction with a representative test frame.