Chuck, I have three that I use. The best overall is one I bought from Dell Woods many years ago. It is a decent filter more towards the narrow band, but I don't think as narrow as today's narrow band filters. This shows great detail and vastly increases contrast even in dark skies on the 22" I also have an OIII and an LPR from Lumicon. They both work very well. The OIII does a nice job on nebulae, especially the planetaries. It does make the stars "disappear" somewhat. I have used it on the Horse head with good results, although I hear the HBeta filters work best on it. The LPR from Lumicon is a good start towards light pollution reduction. Seems as though we need these things too much these days. I can't comment on the reflection nebulae performance, because I don't remember it. I'll check it out later and post. Brent --- Chuck Hards <chuckhards@yahoo.com> wrote:
Expanding our discussion of color filters yesterday, It might be instructive to get the group's impressions of the various LPR (light-pollution reduction) filters we all use.
I use an Orion 1.25" broadband, which I have found to be very useful on just about any emission nebula. Even galaxies and clusters benefit from it's contrast-enhancing ability, but to a lesser extent than emission nebula. I think I mentioned the other day that this filter does a good job of increasing contrast on Jovian features.
Also in my arsenal is a Celestron narrowband filter, again 1.25". This filter is amazing on emission nebula and apertures larger than 4". At first I was annoyed when most of the dimmer stars in the field "dropped out", but the effect on the nebulae themselves more than outweighs this minor aesthetic effect.
I have a Lumicon 2" broadband filter, bought as a "second" from Bill Vorce, due to a small coating flaw. Thus, I can't use it for photography, but it excells when used visually with low-power, 2" eyepieces. Interestingly, it provided excellent city views of comet Hyakutake and Hale-Bopp, when I couldn't get to a dark site.
I have yet to find the LPR filter that works well enough on reflection nebula to justify the cost. Any leads would be appreciated. I also have a hard time justifying the cost of O-III & hydrogen-beta filters, due to the relatively few objects that they enhance.
Were I to actually break down and buy one, I'd probably go with the O-III, since it can be used on planetaries.
Many times I've used a broadband filter to help identify those "tiny blue dot" planetary nebulae, using the "flicker" method advocated by the late Walter Scott Houston. Saved time because with the filter, it isn't neccesary to examine every single star in the field at high power. They jump right out at you with the filter.
I also have a pair of 7 x 50 binoculars that I have fitted with internally-mounted nebula filters. Several years ago, Orion had .965" filters on-sale for only $20 each. They threaded perfectly onto the internal ends of the eyepieces in this particular binocular. This instrument gives the binocular sky a whole new look! M42 & the entire "sword" is an amazing sight in this bino, as well as the area above the teapot of Sagittarius. I may have to try this with the 15 x 70's one day, although I'll have to use 1.25" filters for that bino, to avoid vignetting.
Brent, I'm curious as to your feelings on these specialized filters.
And everyone, please tell us what LPR filters you use, and how you like them.
Thanks!
Chuck
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