A master light frame is a stacked combination of many calibrated light exposures. It is the single file you actually process: one image that carries the signal of all accepted exposures with most of the random noise averaged out.
A single exposure carries the noise of that one frame. A master light averages many calibrated exposures, so random noise drops while signal adds up. That is why integration guides are written in total hours rather than frame counts (rule of thumb, 2026-09).
Four frame types take part in the workflow:
There is no fixed number. Guides give total integration time in hours rather than counts of frames (rule of thumb, 2026-09), and the right count depends on your sub length, target brightness and sky quality.
The same master can come from many short frames or from fewer long frames, as long as the total hours are similar.
To build your own final image from raw data, yes: stacking into a master light is the standard workflow. If you buy or download a processed dataset, that step is already done. The AstrophotoMarket catalog lists such datasets from $4.90 (as of 2026-09).
