The Dysert O'Dea sites are in farmers' fields, but the public have permission to visit "at their own risk." There is no problem taking as many photos as you like.

I agree that the castle, although a nice stop for tea and a look around, is not as interesting as the the high cross and church nearby. You can visit during daylight hours, but be respectful of the property and watch out for cows and the things they leave behind.

There is a map available of the Dysert O'Dea sites...I bought my copy at the castle, but the Ennis tourist office will likely have copies as well. This is one stop where a map or research will come in handy in telling the story of the ruins.

Dysert O'Dea, although so close to so much, is rarely visited by tourists, so congrats on adding it to your itinerary...I think you'll get some very interesting photos in the area.