Ingrid, there is a limit on the size you can upload. eg 200KB for JPEGs. You have to make a tradeoff. I try to keep the "quality" above 90% and scale the image size until I can get it to save in 200KB. Depending on what is in the image 1200*800 will usually get you close.
You don't need to use RAW images for wide angle shots. You will get good results using JPEGs, with ISO6400, and noise reduction enabled.
An 18mm lens will get images with no star trailing of 20 secs. anywhere
in the sky, and much longer exposures if you are imaging at high
declinations. The results should be acceptable with little or no
processing, maybe a little extra contrast if your site has some skyglow.
Hope this helps
raymo
Thanks for the info.
Much appreciated and I will certainly try that next time.
In the meantime, I'm using Snapseed.
It works very well and best of all it's free.