Optolong L-Ultimate 1.25”

Optolong Filters L-Ultimate 1.25” is an ultra-narrowband dual-band filter developed specifically for astrophotography of emission nebulae with color cameras and CMOS sensors. The filter combines extremely narrow transmission windows for H-alpha (656 nm) and O-III (500 nm) with a bandwidth of only 3 nm per line. This high selectivity virtually blocks interfering light from artificial sources such as sodium and mercury lamps, as well as natural sky glow (skyglow).

The result is a very dark sky background and maximum contrast enhancement of emission nebulae, even in the middle of urban areas. Thanks to its dual-band construction, the L-Ultimate is excellent for use with One-Shot-Color cameras (such as ZWO ASI models), as well as monochrome cameras in luminance or narrow-band combinations. Compared to wider dual-band filters such as the L-eNhance or L-Extreme, the L-Ultimate delivers significantly tighter signal separation and deeper detail in structures of nebulae.

The filter is constructed of high-quality optical glass and coated with a durable multilayer IBAD coating. This ensures high transmission in desired lines, scratch resistance and stability in temperature changes.

Application
The Optolong Filters L-Ultimate 1.25” filter is the perfect choice for astrophotographers who want to capture emission nebulae from highly light-polluted locations or under moonlight. Ideal for objects such as the Orion Nebula, Veil Nebula, Lagoon Nebula and North American Nebula. For reflection nebulae or galaxies, this filter is less suitable; for that, the L-Pro is better. The filter is intended for astrophotography only and is not suitable as a solar filter.

Specifications

• Type: Ultra-narrowband dual-band filter
• Barrel size: 1.25”
• Transmitted spectral lines: H-alpha (656 nm), O-III (500 nm)
• Bandwidth: 3 nm per line
• Transmission:>90%
• Material: High quality optical glass
• Coating: IBAD, scratch resistant and temperature resistant
• Usage: Astrophotography with CMOS/CCD and DSLR (with adapter)
• Not suitable as a sunscreen