Optolong IR PASS 685 nm 2 "is an infrared transmitting filter, dedicated for use in planetary astrophotography.

The best way to achieve a noticeable improvement in contrast when photographing planets is to use IR-LRGB imaging, which uses only infrared radiation in the luminance channel, free from most of the distortions typical of the visible range. The ideal solution is therefore to use the Optolong IR PASS 685 nm 2 "filter, which blocks light with a wavelength less than 670 nm and has a very high transmittance for radiation in the IR range.

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.

The most important features of the Optolong IR PASS 685 nm 2 "filter

• filter dedicated to planetary IR-LRGB imaging
• Schott B270 substrate
• scratch-resistant multi-layer anti-reflection coating

Technical parameters

• filter type: IR-pass filter
• filter diameter: 2 "
• transmitted bands: IR, from 670 nm
• average total transmittance (Tave):> 90%
• Filter material: Schott B270 glass
• type of coating: full multi-layer coating (FMC)
• surface quality index: 60/40
• parallelism: 30 "
• RMS execution accuracy: λ / 4
• frame material: black anodised aluminum

Elements of the set

• Optolong IR PASS filter 685 nm 2 "