Astronomik O-III Line Nebula Filter-1.25" w/12nm bandwidth

• Transmission of nearly 100% of both OIII lines
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  Complete blocking of all extraneous wavelength coverages
• The ideal filter for telescopes 10 " (25cm) and larger
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  Main operational use: Planetary nebulas & super nova remnants
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  No moisture-sensitivity, no aging, and totally scratch-proof
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  Excellent carrier material - substrate is optically polished. The optical performance (resolution & contrast) of your telescope is not reduced in any way by the filter.
• 
  Parfocal with other Astronomik filters
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  Glass thickness: 1mm
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  Completely resistant against high humidity, scratches and aging effects
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  Diffraction limited, the filter will not reduce the optical performance of your telescope!
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  Astronomik filters are delivered in a high-quality, long lasting, filter box

From the start, the Astronomik OIII filter has been very specifically designed for the visual observation of gaseous and planetary nebulae. The extremely narrow pass band of the two OIII lines brings a substantial contrast gain to these lines even under best observation conditions. On faint super nova remnants and faint planetary nebulae the Astronomik OIII filter will often make the difference as to whether the object can bee seen or not! Transmission losses and chromatic distortions, which arise with other filters, occur with Astronomik OIII filters only when extremely bright aperture ratios of f/2 and shorter come into play. The Astronomik OIII filters thus can expand the view of dispersed objects, generally speaking, to the whole visual field of view of the eyepiece and are not limited to only the center of the eyepiece.
Due to the high optical quality of the Astronomik OIII filter substrate you will see the same needle-sharp stars as you would from your regular telescope.
Visual observation (dark skies): Very good, huge contrast enhancement at O III-emission nebulae, such as planetaries, Wolf-Rayet nebulae, and supernova remnants.
Visual observation (urban skies): Very good, huge contrast enhancement at O III-emission nebulae
Film photography: It depends, very long exposure time
CCD photography: Good, when used with an additional IR-block-filter
DSLR photography (original): Very good, huge contrast enhancement at O III-emission nebulae
DSLR photography (astro modified): Very good, huge contrast enhancement at O III-emission nebulae
DSLR photography (MC modified): Good, when used with an additional IR-block-filter
Webcam / Video (Planets): Unsuitable
Webcam / Video (Deep Sky): Reasonable, if light pollution is a big problem and OIII Objects are being observed

filter	H-II Gas cloud	planetary nebula	Wolf-Rayet Excitation	Dark	Reflection	Faint H emitting	planets
Baader UHC-S	x	x	x		x
Astronomik UHC	x	x	x
Astronomik O-III		x	x
Astronomik H-ß						x
TeleVue Nebustar	x	x	x
TeleVue O-III		x	x
TeleVue H-ß						x
DGM NPB	x	x	x
Baader Contrast Booster							x
Baader Moon & Sky Glow							x
Lumicon UHC	x	x	x
Lumicon O-III		x	x