Hi all,
Last night, Hickny and I had a session at Randwick (inner Sydney) were we chased down a three PNs.:NGC 2438, 2818 and 2467.
We had three scopes at our disposal, all reflectors, one open truss: 13.1" f/4.5, 8" f/4 and 10" f/5 (open truss). We observed each neb in turn with the same EP with a Lumicon Neb. Filter in each scope and found that the smallest scope, the 8" f/4, gave the brightest image!
Why could this be so?
The image in the other two scopes was fairly much the same: faint but discernable with a litte giggle of the scope. The 8" required no 'giggleing' to see.
Mental.