Lumicon Nebula Filters



The Deep Sky , Hydrogen-Beta , Oxygen III , and Ultra High Contrast Filters are the result of 20 years of steady design improvements, and continue to deliver the highest performance of all anti-light pollution filters obtainable today. The following information recommends which filter to use on which celestial objects, and explains how filter transmissions differ.



Objects


Examples


Best Filter for Viewing


Best Filter for Photography


Stars & Star Clusters


M13, M11


None


Deep Sky


Diffuse Nebulae


Lagoon, Swan


OIII (light polluted sky) Deep Sky, UHC (dark sky)


Deep Sky


Planetary Nebulae


Dumbbell, Ring


OIII (light polluted sky) Deep Sky, UHC (dark sky)


Deep Sky


Faint Planetary Nebulae


NGC 7293, Abell 33, Jones 1


OIII


Deep Sky


Reflection Nebulae


Pleiades, Trifid


Deep Sky


Deep Sky


Spiral Galaxies


M33, M101


None


Deep Sky


Faint Nebulae


Veil, Rosette, N. American


OIII (light polluted sky) Deep Sky, UHC (dark sky)


Deep Sky


Extremely Faint Nebulae


California, Horsehead


H-Beta


Night-Sky H-Alpha
Deep Sky


Ideal for Photographic Applications

 

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Ideal for Visual Usage

 

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Infrared Blocking Filters

3

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Minus Violet Filters

4

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Deep Sky Filter

- Intended for viewing nebulae from light-polluted skies.

- Blocks all mercury vapor and high & low pressure sodium vapor lamp light, neon lights and airglow, while transmitting the rest of the visible spectrum.

- The best all-around visual light pollution filter for use in urban skies.

- This filter also provides high-contrast views of the Martian polar caps

Ultra High Contrast Filter

- Narrow band pass filter (24nm) isolates the two doubly ionized oxygen lines (496 and 501nm) and the  hydrogen-beta line (486nm) emitted by planetary and most emission nebulae.

- Provides superb views of the Orion, Lagoon, Swan and other extended nebulae.

- The best all-around dark-sky nebular filter available.

Oxygen III Filter

- Narrow band pass filter (11nm) isolates just the two doubly ionized oxygen lines (496nm and 501nm)  emitted by planetary and extremely faint nebulae.

- Produces near-photographic views of the Veil, Ring, Dumbbell, Orion, plus many other nebula.

- Hydrogen-Beta Filter

- Extremely narrow bandpass filter isolating the hydrogen-beta line alone (486nm).

- Excellent for viewing the Horsehead, Cocoon and California Nebulae.

- Often the only way to view certain nebulae.

  - It is best used under clear skies with large aperture.

Comet Filter

- Designed to enhance the cyanogen (CN) frequency found in comet tails..

Exit Pupil Specifications:

The exit pupil of a telescope is a measure of specific magnification, which differs from absolute magnification, and which determines the surface brightness of an extended object image. Exit pupil diameter may be expressed as the quotient of eyepiece focal length divided by the telescope's focal ratio. For example, a 32mm eyepiece used on an f/10 telescope will have a 3.2mm exit pupil. Each Lumicon filter has an optimum eyepiece exit pupil range shown below.



Filter Type


Deep Sky


UHC


OIII


H-Beta


Bandpass


90nm


22-26nm


10-12nm


8-10nm


Optimum Exit Pupil (Light-polluted sky)


0.5-2mm


1-4mm


2-5mm


3-7mm


Optimum Exit Pupil (Dark sky)


1-4mm


2-6mm


3-7mm


4-7mm



Notice:


As filter bandpass decreases, optimum exit pupil size tends to increase. To determine the best eyepiece focal length to use with a given filter, simply multiply the Exit Pupil value shown above by your telescope's focal ratio. For example, if you are using the Lumicon H-Beta filter at a dark site and your telescope has an f/6 focal ratio, the best range of eyepiece focal lengths to use with this filter is [(4 to 7) x 6] = 24mm to 42mm.

Filter Construction:

Lumicon nebula filters are made using thin-film dielectric coatings on optically flat glass. These exclusively designed dielectric coatings consist of over 30 alternating layers of several different materials. Each layer is about a wavelength of light thick and has a thickness accurate to 2 - 3 angstroms. Lumicon nebula filters include anti-reflection coatings on both sides to prevent ghosting and increase light transmittance. They also have a hard, electron-beam deposited coating for mechanical protection. While still delicate, Lumicon filters may be carefully cleaned with isopropyl alcohol, or Lumicon’s Advanced Cleaning Kit

Mechanical Design:

These filters thread directly into most eyepieces and telescope accessories. Threads are standard for 1" filters. 48mm filters are standard for 2" O.D. eyepieces.

Bandpass:

These Lumicon filters reject man-made and natural light pollution. Mercury light pollution occurs at 365, 405, 436, 546, 577, and 617nm. High-pressure sodium streetlights emit at 570, 583, 600, and 617nm. Natural airglow occurs at 558 and more weakly at 630nm. There is a window of greatly reduced light pollution from 440nm (blue) to 540nm (green). The Lumicon Deep Sky Filter has a wide 90-100nm bandpass for most of this range (441-535nm) to yield maximum transmission of light from stars and galaxies. The UHC Filter has a narrow 22nm bandpass through 484-506nm. The OIII Filter has a very narrow 11nm bandpass for 495-501nm, and the H-beta Filter has the narrowest bandpass of all - only 8nm centered at 486nm. The narrower the bandpass, the higher the rejection of light pollution and the blacker the skies. However, a narrower bandpass also means fainter star images. Nevertheless, the Deep Sky Filter has high transmission for the photographic red nebula emission lines.

Nebula Emission Lines:

The main visible radiation from emission nebulae consists of doubly ionized oxygen near the wavelength of 500nm. There is also weaker emission due to hydrogen-beta at 486nm. The invisible but photographically important emission of red hydrogen-alpha and ionized nitrogen occur near 657nm.

Best Nebula Filters - For Selected Objects

Nebula Name Best Filter
M1 Crab nebula UHC
M8 Lagoon Nebula UHC
M16 Eagle Nebula UHC
M17 Swan Nebula O-III
M20 Trifid Nebula UHC
M27 Dumbbell Nebula UHC
M42 Orion Nebula UHC
M43 Orion Nebula H-Beta
M57 Ring Nebula UHC
M76 Little Dumbbell Nebula UHC
M97 Owl Nebula O-III
NGC40   UHC
NGC246 Skull Nebula O-III
NGC281 Pac-Man Nebula UHC
NGC604 in M33 O-III
NGC896/IC1795   UHC
NGC1360   O-III
NGC1491   UHC
NGC1499 California Nebula H-Beta
NGC1514 Crystal Ball Nebula O-III
NGC1999   none
NGC2022   O-III
NGC2024 Flame Nebula UHC
NGC2174   UHC
NGC2327   H-Beta
NGC2237-2239 Rosette Nebula UHC
NGC2264 Cone Nebula UHC
NGC2359 Thor's Helmet O-III
NGC2371-2   O-III
NGC2392 Eskimo Nebula O-III
NGC2436   UHC
NGC2438 in M46 O-III
NGC2440   UHC
NGC3242 Ghost of Jupiter UHC
NGC4361   UHC
NGC6210   O-III
NGC6302 The Bug Nebula O-III
NGC6334   UHC
NGC6357   O-III
NGC6445   UHC
NGC6543 CatsEye Nebula O-III
NGC6559   UHC
NGC6781   O-III
NGC6804   O-III
NGC6888 Crescent Nebula O-III
NGC6905 Blue Flash Nebula UHC
NGC6960-6995 The Veil Nebula O-III
NGC7000 North America Nebula O-III
NGC7008   O-III
NGC7009 Saturn Nebula none
NGC7023   Deep Sky
NGC7026   O-III
NGC7027   O-III
NGC7048   O-III
NGC7129-7133   UHC
NGC7139   O-III
NGC7293 Helix Nebula O-III
NGC7538   UHC
NGC7635 Bubble nebula O-III
NGC7662 Blue Snowball none
NGC7822   UHC
IC405 Flaming Star Nebula Deep Sky
IC410   O-III
IC417   H-Beta
IC434/B33 Horsehead Nebula H-Beta
IC1318   H-Beta
IC1396   UHC
IC1848   UHC
IC2177 Seagull Nebula H-Beta
IC4628   UHC
IC5067-70 Pelican nebula UHC
IC5076 inNGC6991 H-Beta
IC5146 Cocoon Nebula H-Beta
PK64+5.1 Campbell's Hydrogen Star H-Beta
PK164+31.1 Headphone Nebula UHC
PK205+14.1 Medusa Nebula O-III
Sh2-13   UHC
Sh2-54   UHC
Sh2-84   UHC
Sh2-101   UHC
Sh2-112   O-III
Sh2-132   O-III
Sh2-142   O-III
Sh2-155   Deep Sky
Sh2-157   UHC
Sh2-170   UHC
Sh2-171   UHC
Sh2-235   H-Beta
Sh2-254-5-6-7-8 inIC2162 H-Beta
Sh2-261   UHC
Sh2-276 Barnard's Loop H-Beta
Sh2-311 in NGC2467 UHC
vdB93(Gum-1) near IC2177 H-Beta