down to 18

Blinked the stacked image (of the Ring) with SkyTools.

Stars down to magnitude 18 and change.

J185334.1+325949: 16.90
J185330.2+325925: 17.15
J185329.2+325901: 17.64
J185324.8+330005: 17.20
J185324.3+330046: 18.22
J185336.7+325956: 18.05
J185348.6+330253: 18.16

Wow.

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That's appropriate. The C14 is rated to mag 16.2. And a general rule of thumb is that photography adds 2 magnitudes.