I did some imaging on the night of September 18, and was intent on getting NGC 7293 (Helix Nebula).
My problem was it was too low after dusk, so I got close to an hour on The Dumbbell Nebula in my AT115EDT using the 0.8X FF/FR. I was a bit worried about only having an hour, but it turned out alright.
Once the Helix got 20° up, I decided to start taking images. I had re-checked focus (it had drifted slightly), centered up NGC 7293, taking some test subs, and then let it go. The plan was to image a good 2.5 to 3 hours.
Emphasis on the word, "plan".
You know that thing called a, "dew shield"? It acts as a, um, SHIELD. Against DEW. Especially if the shield is USED. 'Cuz a shield only works if it's used.
Guess what happens when it's not?
Yep. I forgot to extend the dew shield. The result was that I was only able to salvage 78 minutes' worth of data. But 1.3 hours is still 1.3 hours more than I started the night.
Both were shot from Wilmot, OH (~20 miles SW of Canton) with a Nikon D5300 using unguided 30-sec subs @ 800 ISO on a Sirius EQ-G mount.