M81 in HA,G,B

Your site is offline at the moment Dave...

Seems to be working fine at 4:45pm Seanie, but thanks for the heads up.

Dave - it is recommended that flats are taken at your precise focus point. That could become a right royal pain. But in reality, we don't suffer extreme temperature swings here in Ireland so the focus point shouldn't change enough for it to be a problem for pretty pictures.

What I will do (when I get my lightbox) is setup the optical train, foucs and then shoot some images to make sure all is in order. then I'll shoot the flats at that precise focus point (for each filter). They'll now be master flats. I'll also shoot darks for the same length of time as the flats were exposed. Combining the two then, I'll have a dark-subtracted master flat set for each filter. I may need to go the extra mile for science stuff and shoot flats at differing focus points - but I'll cross that bridge later...

That should be job done - until the optical train changes...

Dave