The dual-band Optolong L-Ultimate 2" filter is an excellent tool especially for photographing bright emission nebulae with digital SLRs and monochrome cameras in conditions of high light pollution.

This filter transmits over 90% of the light in the spectral lines emitted by ionized hydrogen (Hα) and oxygen (OIII) atoms. Combined with the efficient cutting of spectral lines characteristic of sodium and mercury lamps, this allows you to capture sharp and contrasting images even near large cities or during bright moonlit nights. The filter is characterized by a very narrow half-width of the pass-throughs of only 3 nm, thanks to which it allows to obtain much better contrast and much darker background than the two-band L-eNhance and L-eXtreme filters.

In order to further improve the optical parameters, this filter is covered with a full multi-layer anti-reflection coating applied using ion implantation techniques. Thanks to this, the coatings are not only perfect in terms of optics, but also very durable and scratch-resistant.

Attention! The Optolong L-Ultimate 2" filter should not be used with optical tubes with the highest light shades.

The most important features of the Optolong L-Ultimate 2" filter

• high transmission dual-band filter for Hα and OIII lines
• Half-width of the transmission bands at the level of 3 nm
• very high efficiency of cutting out light pollution
• reduced halo effect with bright stars
• scratch-resistant multi-layer anti-reflection coating

Technical parameters

• filter type: dual-band filter
• filter diameter: 2"
• half bandwidth (FWHM): 3 nm
• pass bands: Hα, OIII
• maximum transmission: ~ 90%
• blocking range: 300 - 1000 nm
• equivalent optical density for blocking range:> OD4
• type of coating: full multilayer coating (FMC)
• substrate material: optical glass
• surface quality index: 60/40
• parallelism: 30 "
• RMS execution accuracy: λ / 4

Kit components

• Optolong L-Ultimate 2" filter

Guarantee

24 months