View Single Post
  #4  
Old 18-05-2016, 12:09 PM
multiweb's Avatar
multiweb (Marc)
ze frogginator

multiweb is offline
 
Join Date: Oct 2007
Location: Sydney
Posts: 22,060
Hi Ray, I've noticed that many times as well. It makes sense to me. Taking mount performance out of the equation and assuming you have an hypothetical mount that tracks perfectly the seeing comes and goes in small intervals of time usually tens of minutes. It is very obvious when guiding let's say a series of 5min subs. This was very obvious at the SPSP. The seeing being very good and the temperature stable it was very easy to pick up small variations. So you might end up with very sharp subs and some others not so sharp. That's in a perfect world. Add the mount PE and wind buffeting and other factors on top and you invariably will end up with bigger star profiles the longer you expose. There is also the well depth of your camera. More exposure time, more photons and the star is usually bigger.
Reply With Quote