The Optolong L-Ultimate dual narrowband filter is designed to drastically reduce the effect of light pollution and capture a very specific wavelength of light emitted from deep space emission and planetary nebula. Its two ultra-narrow 3 nm passing bands isolate the nebulae emissions in Ha (red) as well as OIII (green-blue).

This effectively means local light pollution is much less significant and even imaging during a full moon is possible too as all other wavelengths outside of the specific Ha and OIII signal are blocked from entering the camera. The L-Ultimate filter is literally the ultimate filter for astrophotography under urban light polluted skies.

Features:

• Blocks the artificial light from mercury vapour lamps, both high and low pressure sodium vapour lights and the unwanted natural light caused by neutral oxygen emission in our atmosphere (skyglow).
• Maximum transmission of the main nebula emission lines at OIII (496 nm and 500 nm) and H-alpha (656 nm)
• Two transmission bands with a bandpass of 3nm each
• Designed mainly for astrophotography with color cameras
• Also helpful with monochrome cameras, no need to change filters for catching both lines
• Ideal for urban areas with extreme light pollution
• It incorporates an IR/UV cut filter that is necessary in astrophotography, especially for astronomy cameras that are sensitive to the infrared radiation.
• Ultra-thin filter cell to maximise the compatibility with most filter wheels.
• Multi-layered anti-reflection coating
• No obvious halo around bright stars
• Cell in an aerometal material, CNC machined, sand blasted, black anodized and laser engraved
• Includes a PP plastic case, high pressure EVA case lining

The interferential coating is deposited on the substrate using electron-beam gun evaporation with Ion-assisted deposition coating technology. This essentially increases the filter durability and resistance to scratching, as well as stability on CWL (central wavelength) and no deviation affected by temperature changes.

The planetary rotation system offers precision and homogeneity of coatings ensuring high transmission of pass-band and high optical density off-band.

Spec:

• Transmitted lines: OIII (500.7 nm), H-alpha (656.3 nm)
• FWHM: 3nm
• Suitable for: 2" Filter threads
• Blocking range: 300 - 1000 nm (UV/IR cut)
• Blocking: >OD4
• Substrate: Optical glass made by Schott
• Substrate thickness: 2mm
• Surface quality: 60/40
• Optical flatness: λ/4 rms
• Parallelism: 30 arc sec
• AR coating: Multi layer
• Cell: Aluminum, black anodized

Whats included:

1. L-Ultimate Filter
2. Protective box, foam lined

IMPORTANT: Its essential that when placing an order, you include a valid 'Contact Telephone Number' for the delivery address or for the person receiving the item. This is necessary to avoid potential delays or problems with your delivery.

Shipping Disclaimer: All of our parcels are sent via a 3rd party registered courier service to ensure safe and prompt delivery. While we endeavor to ensure that all parcels are delivered within the specified time frame, 'Horizon Astronomy' can not be held responsible for delays due to adverse weather conditions or other courier/technical related issues outside of our control.