The time it takes to read out the CCD after and exposure or dark exposure. This is done by a crystal controlled clock and the time depends on the details of the PROM programming that controls the read out process. It is very close to 47 seconds and fixed. The time it takes to transfer the data stored in the Memory card by a Read operation to the hard disk. This is done by a QBasic program and is subject to the Windows operating system.
Timing depends on whether other windows are open.
The attempt is to take data with all other windows closed. This is a fairly constant number, but can change if Windows decides to do something. The time is about 64 seconds on my 200 MHz K6. A Read operation where there is no attempt to save the data. The shortest possible dark exposure is one taken by two successive scans.