Preview image here is cropped a lot, and doesn't use the luminance data. Stars are not great, should take some shorter exposures to capture the stars better?
https://obj.bortle.org/deepsky-observer/m51_fsq85_210x180s_l.tif
https://obj.bortle.org/deepsky-observer/m51_fsq85_219x180s_r.tif
https://obj.bortle.org/deepsky-observer/m51_fsq85_228x180s_g.tif
https://obj.bortle.org/deepsky-observer/m51_fsq85_228x180s_b.tif