I have a basic question... I was wondering how the camera/software/firmware deals with binning. If I bin my STT-8300 at 2 x 2 is the data for the 4 pixels summed or is it averaged? I have recently seem several posts in various forums stating that binning 2 x 2 gives you 4 times the signal. However, I have always assumed that the 4 pixels are averaged and the S/N gain from binning is based on the averaging of the pixels. Dean J.
Data is summed, not averaged. Depending on the sensor and the electronics, this is often done at the hardware level, reducing the amount of data to transfer over the interface to the PC. Binning can be done across the row or column, again depending on the sensor and electronics. e.g. some cameras can be binned 2x1, 1x2, or 2z2. Basically it gives you what appears to be a bigger pixel (lower resolution), and faster download time.
Please note that some camera models do reduce the A/D converter gain when binned, because the readout register has more dynamic range than the pixels. You'll see the EGAIN number in the FITS header change when that is the case.
