Quote:
Originally Posted by Don Pensack
For instance, a wider filter would show more stars (an observer might like that) and only sacrifice a bit of contrast on the nebula.
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Agree 100% Don
Quote:
Originally Posted by Don Pensack
And a wider filter would be usable at a higher power without dimming the overall field image excessively. That reduced dimming could be important in a small aperture, even at low powers. A wider filter might do fine in a larger aperture when the view is already great and you just want to turn up the contrast.
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Agree 100% again
These are the exact reasons the Astronomics UHC sees a lot of use in all my scopes, from the 10" SDM up to and including the 18" Obsession. On targets like the Tarantula Nebula with a lot of embedded stars it is the filter of choice in providing the most aesthetically pleasing view. Unfortunately Dave Knisely has blinkers on when it comes to filters and he presumes that the narrowest narrowband filters are the only ones which will work, without considering that people might be viewing different targets and trying to achieve different goals to what he is.
Quote:
Originally Posted by Don Pensack
The wider filter doesn't make the nebula invisible though, and your telescope won't break if you use one. I think if one chooses a filter knowing what the filter is, what it does, and how it differs from its competitors, there is nothing wrong with the choice. But since nebula filters are fairly expensive, going into the choice blind, without knowing what one is choosing, might result in results that are less than might be delivered with another filter.
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Absolutely and the reason I recommended the DGM NPB as the best choice for a 1st filter. It is about the tightest of the narrowband filters and one of the cheapest to boot. Myself, Mike Salway and David Hough were actually the first people to bring a DGM NPD into Australia when I purchased them directly from Dan McShane at DGM Optics, long before the rest of the astronomical community knew what a good thing they were. If cost is not a consideration there is certainly room in the tackle box for both a DGM NPB and an Astronomics UHC.
Quote:
Originally Posted by Don Pensack
I do wish the manufacturers spent more time giving us specifications like bandwidth and transmission percentage averages at the important wavelengths instead of idealized transmission curves.
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Agreed.
Cheers,
John B