The Problem
Shooting from Bortle 8 skies with an f/5 scope means exposures get blown out or go white fairly quickly. Shooting long exposures is doable but with my skies and setup I’d greatly benefit by using a light pollution filter. But what type of filter would work best for my rig a 2″ round or clip-in, etc. What’s available for my older Nikon D5100 DSLR and where would the optimum location for a filter reside in my light train?
With these questions in mind I ventured to find out. My first stop? A quick scan of the owner’s manual for my Meade Series 6000 70mm Quad APO Astrograph but surprisingly this revealed no information at all. There is this in the owner’s manual:
Not much help really and the “picture” mentioned above is not actually on the whopping 2 page owner’s manual. So after searching online for information on adding a filter to my specific scope and even calling Meade Customer Service for assistance; I got nowhere. I felt sure that a filter could be added I was just seeking assistance with the best approach.
The Test
I didn’t have a 2″ filter so I bought an inexpensive 2″ Solomark Moon & Sky Glow filter for $20 bucks off Amazon mainly as something to test with before taking the plunge and buying a high dollar LPS imaging filter. I’m glad I decided on that route. I very quickly found out that the 2″ filter did fit nicely between the 48mm to 42mm adapter that is used to connect the DSLR to the telescope. The line up goes like this: DSLR, Nikon T-Ring adapter, 48mm to 42mm adapter, Moon & Sky Glow Filter, telescope. Success! Not quite. Adding the filter at this point in the light train increased the distance that the camera was from the back of the scope. By pushing the DSLR back slightly I was then unable to achieve focus. The focal point with this telescope is very close to the end of the scope with the focuser almost fully racked in. There is hardly any travel to work with. Back to the drawing board.