| s58y |
| (Postmaster) |
| 07/02/09 12:29 PM |
|
Re: Which H-alpha filter?
|
Quote:
Interesting. What filter is on your Hutech 30d? Clear or astronomic ir cut? I ask because I noticed much more in the way of star halo effect with my self modded 350d "no filter replacement" than my new 1000dh with the mild ir cut, when using the ha filter. My 80ed also seemed to cause more bloat and halo than my meade sn6 reflector or a quality camera lens would.
The 30D has the Hutech UV/IR blocking filter. For some reason, I never can find a sharp focus point when using either of the H-alpha filters, compared with an Astronomic UHC or IDAS LPS filter (or no filter). The problem was worst with the 13nm H-alpha filter. Maybe some other setup would get the worst bloating with the Baader 7nm filter?
Unfortunately, I can't use the Baader 7nm inside my ancient Nikon 800mm lens, so I may end up getting one of those Astronomik 6nm clip filters, an Astronomik 48mm threaded 6nm filter (rim is narrower than the Baader), or even a 50mm round Astrodon 5nm filter to fit inside the lens.
Murphy's law says if I get the 6nm clip filter, I'll soon move to either a full-frame DSLR or a real astrocam. If I get the 5nm Astrodon, I'll never move to a real astrocam. If I get the 6nm threaded filter, I'll end up with a camera requiring square 50mm filters.