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Orion Broadband Skyglow Filter

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Date: 5-3-2003
Price: $59.95
Design: Light pollution reduction filter.
Description: Normal 1.25" LPR filter from Orion.

The Problem

Light pollution is an ever-encroaching problem for urban astronomy and broadband filters seem to be the answer, but are they?  After using the Skyglow Broadband filter over the last 12 months I have found the majority of my viewing is done without this simple filter.  So, do you need broadband filters within urban or even dark sky areas?  The answer is yes; this little filter excels at improving the images of emission and planetary nebulae.   

Performance

I have owned Orion’s Skyglow Filter for over 12 months and found this little filter to reduce background spectral wavelengths of 300 – 480 nm and 530 – 630nm, which results in a demonstrable reduction of light transmission - the resultant star field background is darker.  This is the problem; the filter reduces light transmission and makes viewing of 6th magnitude star fields difficult.   I utilize a 200mm reflector telescope (SVD 8 EQ) and have found that the Skyglow does not improve viewing when utilized for its advertised purpose of reducing background skyglow.  I have found that the filter actually reduces the resolving capabilities of my telescope - the Skyglow is not recommended for star field use.

Emission and Planetary Nebulae Observations

This is where the Skyglow Filter excels.  I have been chasing nebulae from my backyard with increasing frequency and, as my observational abilities improve, I have found this little filter to significantly enhance light transmissions within the blue/green and red spectrum (480nm – 530nm and 630nm – 700nm wavelengths). The resulting spectral enhancement facilitates greater ease in discovering emission and planetary nebulae – they actually “jump-out” when scanning selected regions of the firmament. 

The detail this simple filter affords when viewing emission nebulae is worth the money alone.  Normal viewing of the Orion Nebula without the filter is fascinating, but viewing this nebula with the filter in-place is truly astonishing.  You can spend hours studying its inner detail, the filaments and brightness contrasts.  The Orion Nebula comes alive and you feel fortunate that is marvelous sight is within our astronomical backyard.

Lunar Observation

Although this filter is not designed for lunar use I happened upon it when moving my telescope to another region of space crossing the Moon’s reflection.  With a 200mm reflector the moon’s reflection is blinding but this simple filter reduced the glare significantly to allow improved lunar surface observation.  I have used Orion’s Moon Filter and found the lunar surface interesting but the filter blocked too much detail.  But, the Skyglow Filter enhanced the lunar surface detail significantly; the lunar surface actually became interesting.

Conclusion

Purchase a broadband filter! It does not have to be an Orion product but it does have to be manufactured with high quality optical glass by a manufacturer utilizing the highest quality standards in production, coatings and polishing (more on this in a future article).

Submited by - Charles Haase - Cleveland, OH - c.r.hasse@worldnet.att.net

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