Practical choices that decide image quality. Sub-exposure length: long enough that sky-background noise dominates read noise (so read noise becomes negligible), but short enough to avoid saturating stars, tolerate guiding errors, and discard fewer frames. Light pollution and f/ratio shorten the optimal sub; narrowband lengthens it. Total integration matters more than any single sub — hours, not minutes. Session planning: image targets near transit (highest, least atmosphere), plan around the meridian flip, and collect calibration frames. Many short well-guided subs beat a few long risky ones.