Keep 16-bit for serious processing.
Use 16-bit TIFF or similar formats when the image still needs stretching, color work, gradients, masks or denoise.
Bit depth converter for astrophotography.
Bit depth is not just a file setting. It affects how much tonal information survives when you move from processing to web, print or archive outputs.
Use 8-bit for final web output.
Once the image is finished, 8-bit PNG or JPEG can be fine for sharing, as long as the conversion happens at the end.
Convert after decisions are finished.
Changing bit depth too early can remove subtle gradients and faint signal before the final image is ready.
AIT tool
AIT Image Converter is for repeatable export work.
Use it to prepare images for web, print, archive or workflow handoff without treating every export as a manual one-off.