Astronomik OIII Filter for Visual Observation of Nebulae

The Astronomik OIII filter is specifically designed for the visual observation of gaseous and planetary nebulae. With its extremely narrow bandpass focused on the two OIII lines, it significantly enhances contrast, even in ideal viewing conditions. The Astronomik OIII filter is a must-have tool for observing faint supernova remnants and planetary nebulae, often making the difference between seeing or missing the object!

Main Use

The optimal use for the Astronomik OIII filter is with telescopes with apertures larger than 6" (150mm) and an aperture ratio between 1:3.7 and 1:15. Astronomik OIII filters ensure excellent transmission and minimal chromatic distortions even in telescopes with very bright aperture ratios of 1:3 and beyond. These filters expand the view across the entire field of view of the eyepiece, offering more than just a centered observation.

Best for Large Apertures

This filter is best used with telescopes that have an aperture larger than 6" (150mm). For experienced Deep Sky observers with telescopes larger than 10" (250mm), the Astronomik OIII filter is often preferred over UHC filters. The high optical quality of Astronomik substrates guarantees needle-sharp stars without compromising your telescope’s optical performance.

Key Features:

• 95% transmission at 496nm and 501nm (OIII)
• Complete blocking of all unwanted wavelengths
• Ideal for telescopes 10" (25cm) and larger
• Optimal for planetary nebulae and supernova remnants
• Moisture-resistant, scratch-proof, and long-lasting
• Optically polished substrate ensures no reduction in telescope performance
• Parfocal with other Astronomik filters
• Glass thickness: 1mm
• Delivered in a high-quality, durable filter box

Suitability:

• Visual observation (dark skies): Excellent, provides significant contrast enhancement for OIII-emission nebulae
• Visual observation (urban skies): Very good, huge contrast enhancement at OIII-emission nebulae
• Film photography: Requires very long exposure times
• CCD photography: Good, when used with an additional IR-block filter
• DSLR photography (original and astro modified): Very good, offers large contrast improvement for OIII-emission nebulae
• Webcam / Video (Deep Sky): Suitable if observing OIII objects with heavy light pollution