Exposure time directly scales signal: Detected electrons = Photon flux × Exposure time × QE. Signal-to-noise improves as √(exposure) for shot-noise-limited imaging. Practical range for smFISH: 50-500ms depending on fluorophore brightness and excitation power. Frame time = Exposure time + Readout time. For sCMOS with rolling shutter, readout can overlap with next exposure.
Acquisition Parameter
Exposure Time
How long the camera collects light
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Definition
The duration for which the camera sensor collects photons for each image. Longer exposures collect more signal but slow acquisition; shorter exposures enable faster imaging but require brighter samples.
Technical Details
Simplified
Like holding a bucket in the rain—longer you hold it, more water you collect. But if you need to fill many buckets quickly, you can't wait too long for each one. The art is finding the sweet spot where you collect enough signal without taking forever.
Why It Matters
Exposure time is the primary control for balancing speed vs. signal. For the Tzumin Lee Lab's 500-plane Z-stacks with 6 channels, even small changes in exposure time multiply into significant total acquisition time differences.
Practical Example
Current Nikon system uses ~200ms exposure. With the 5-camera E9 system, similar signal levels might be achieved at 100-150ms due to higher collection efficiency, further improving throughput.