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http://www.astrosurf.com/buil/us/spe6/planet.htm

This is a great resource for spectra of Nebula images, including M57, NGC7662, and others. Try an overlay of the spectra, and the transmission of this new filter; More than 95% of the desired light, and nearly zero of the background and skylight.

A newly refined Precision Interference Filter for Astronomers that selectively transmits nearly 100% of the Hydrogen and Oxygen emission of Galaxies and Nebula while eliminating the background polluting light. Produced exclusively for EBay customers as an economical yet improved NPB or LPF Deep Sky Filter. This Filter has significantly improved performance than those we make for our OEM customers such as Thousand Oaks and DGM. This filter has had significant development to produce excellent transmission of the Oxygen lines at 496.9 nm, 500.4 nm, as well as the 486 Hydrogen, and also the Hydrogen Alpha 656.3. All lines are transmitted >95% efficiently, while attenuating OD3+ Average of the entire CCD spectral range. This is a monolithic substrate, with sputtered coatings on outer surfaces that permit this exceptional performance. The filter has an exceptionally pass-band, and very good attenuation of the remainder of the visible and Near IR spectrum. This is a relatively narrow pass band nebula filter.

Suggested for viewing the Horsehead Nebula; passing efficiently the Hydrogen Beta and Oxygen III emission while attenuating sky glow.

The broad-band "Light Pollution Reduction" (LPR) filters are designed to improve the visibility of a variety of Deep-Sky objects by blocking out the common Mercury vapor, Sodium, and some other emission lines from man-made or natural sources which contribute to light pollution, while letting through a broad range of other more useful wavelengths. Since the eye is mainly a "contrast detector", this selective screening out of some of the background skyglow increases the contrast and helps Deep-sky objects stand out more noticeably. While these filters do not eliminate the effects of light pollution or make the objects brighter, in many cases, these filters can improve the visibility of some deep-sky objects to at least some degree.

The filter is mounted in a threaded eye piece adapter commonly refered to as 2". (Actually a 48 mm standard configeration.)and has an glass filter dimension of 47 mm.

Specifications follow: Central Wavelength 494 nominal, To pass 480 to 510 nm, as well as 656 nm, Typical transmission >90%, Blocking OD 3 typical of interfering light. Filter supplied with actual spectral data.

If you don't find your need, try a wild card search. Go to my BJOMEJAG EBUYER STORE and add an * or so to the description, to get close matches.

For a most comprehensive assortment of filter solutions, follow the link at my store, under "Technical Data" to the Omega 'Build A Filter' tool. Millions of potential matches are available. Prices are very reasonable if you indicate "cosmetic seconds acceptable".

On Aug-31-09 at 17:34:01 PDT, seller added the following information:

Sellers: Get your own map today. Click here now. Simple."