Quote:
Originally Posted by mental4astro
What would be the smallest aperture suggested for the NPB filter?
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Hi Alex,
It would work well in a telescope of 4" aperture or more. Whilst the view would be dim in a small scope, the contrast gain would still be quite noticeable under dark skies. It's all about increasing the signal to noise ratio, which applies to all filters. I have used OIII filters which block out more light than the NPB in 4" and 5" scopes in the past, with good results. I have used the Astronomiks OIII on a 4" Takahashi FS-102 and a Televue Bandmate OIII on a Televue NP-127. In fact at 2007 Texas Star Party, myself, Gary Kopff and Andrew Murrell were observing with Al Nagler with his personal Televue NP-127 and we were looking at the Veil Nebula. We first tried a Televue Bandmate filter (OIII). We then tried a Televue Nebustar filter (UHC) and then Al Nagler decided "for fun" he would "stack" both filters. The view for a 5" telescope with both filters stacked was exceptionally good. Which shows the critical thing with all deep sky observing is dark skies.
In a medium/large scope the DGM NPB works very well on a few targets which "some" narrowband or OIII filters don't do all that much with. The Crab Nebula (M1) which is a supernova remnant, is one of these for instance. It also does a tremendous job on the Orion Nebula (M42), the Tarantula Nebula (NGC 2070), Eta Carina (NGC 3372) and a host of other planeteries and emission nebula. If I could only own 1 filter (I own > 30), the one filter I would pick each and every time would be the DGM NPB.
In regard to the packaging, my DGM NPB filter, which I purchased over 5 years ago, came direct from DGM optics, not Omega who are the manufacturer. My filter was very nicely packaged in a hard but slightly flexible plastic case and was clearly machine laser inscribed on the side as to its origin, size and type. Couldn't fault how it arrived.
Cheers,
John B