Does anyone on here know why a camera's accuracy would drop when you reduce the delay time after the pulses?

Question

I'm using a TSL1401R-LF Linescan Camera that reads in a 1 X 128 array of pixels. Here is the datasheet. When I used 170-microsecond delay the accuracy was pretty high and the camera's outputted values were noticeably lower when an object passed through its line of vision. When I attempt to reduce that to a 20-microsecond delay I would still see lower values if a cover the camera completely or higher value if I shine a light on the camera, but the change is slight and there is not change if I hold an object from a distance. The lower the delay time, the worse the accuracy. This confuses me because the datasheet states that the minimum delay time can be as low as 20 nanoseconds for the SI pulse and 50 nanoseconds for the CLK pulses. Since I'm still clearly above the minimum why am I losing so much accuracy? I've never worked with a camera or scanner before so I'm not sure if this is normal of if I'm doing something wrong.

Answer 1

You are essentially reducing exposure time, which will make the picture darker.

Some cameras can increase the voltage in the sensor to compensate (which will lead to higher noise), but adjusting the exposure time is the best way to change the sensitivity of the camera (typically, you'd determine the brightest pixel, and adjust the exposure time to keep it within a sensible range (e.g. 90% to 95%).