Why is QHYCCD's QHY5III174 frame rate 138, and the SONY technical manual claims that the IMX174's chip frame rate is 164?
The frame rate of the chip is related to the drive frequency. When the drive frequency is higher, the frame rate is also higher. But not the higher the drive frequency, the better. When the driving frequency is close to the limit frequency, the readout noise will increase and the heat generated by the chip will increase.
Therefore, the QHYCCD camera has optimized the driving frequency, and has chosen a balance point that can take care of the frame rate and better readout noise performance.