Baader 31 mm CMOS Optimized LRGB Filter Set

Baader 31 mm CMOS Optimized LRGB Filter Set

Optimized for current CMOS cameras, these 31 mm LRGB filters from Baader have a balanced design with excellent contrast and transmission. These filters are compatible with extremely slow f/15 telescopes, extremely fast f/1.8 telescopes, and everything in between. Highly desired 1:1:1 subframe exposures are made possible by this balanced design, ideal for automated imaging. Steep slopes at all transmission curves significantly increase transmission for each RGB color channel. This results in filters with color contrast that is in accordance with conventional CMOS quantum efficiency and s/n ratio, as well as in incredibly low levels of stray light and reflections. Unwanted reflections are curtailed even more by lens edges that are blackened all the way around with filter-lead-side-indicator in the form of a telescope-sided black outer rim.

In addition to the RGB (Red/Green/Blue) color filters, this CMOS optimized Baader filter set also contains a Luminance “L” Filter that serves as a UV and IR emissions blocker while also allowing visible light between 420 nm and 685 nm to pass through up to 98% of the time. Typically, when imagers use red-sensitive digital, CCD, or CMOS cameras for stellar astrophotography, they expect their results to have blurry stars. The “L” filter prevents this altogether. Rejects hazardous infrared thermal radiation as well.

For cheaper filters made by other manufacturers, one of the main causes of premature aging is the moisture accumulation stemming from micro-cracks formed around all edges. These micro-cracks develop as a result of being cut from a larger plate instead of individually coated and planeoptically polished with Reflex-Blocker™ hard coatings and Life-Coat™ sealed coating edges like Baader’s CMOS Optimized 31 mm LRGB Filters. Furthermore, because Reflex-Blocker™ coatings are resistant to scratching, the quality of these filters will remain high indefinitely regardless of cleaning frequency. Lastly, current standards for filter thickness are met with these parfocal filters.

Baader CMOS Optimized LRGB Filter Set Highlights

• Optimized for CMOS cameras, the filters in this Baader 31 mm LRGB (Luminance/Red/Green/Blue) Bandpass Set are compatible with telescopes ranging from f/15 to f/1.8.

• All three RGB color channels offer incredibly high transmission for heretofore unheard-of reductions in stray light and reflections.

• A balanced design allows the capture of subframes with identical 1:1:1 exposure times, essential for automated imaging applications.

• Each filter in this set contains transmission curves with steep slopes for improved contrast.

• These filters have been independently coated and planeoptically polished with Reflex-Blocker™ and Life-Coat™ hard coatings and sealed coating edges rather than carved out of a single plate of glass.

• Current filter thickness standards are met with these parfocal filters.

• Edges are blackened all the way around with telescope-sided black outer rim serving as a filter-lead-side-indicator for further reduction of reflections that occur because of light falling onto the filter's edge.

• Simultaneous acceptance of as much as 98% of visible 420 nm to 685 nm transmissions, and rejection of light from unwanted UV and IR sources, including detrimental thermal radiation in the infrared, is enabled by the Luminance "L" filter.

• With the "L" filter, images of stars produced by digital, CMOS, and CCD cameras sensitive to red appear sharper.

• Maximize the transmission of O-III line objects for the finest deep sky S/N yield possible by using the "B" and "G" filters in conjunction to capture twice the energy from that part of the spectrum.

• Infrared and near infrared spectral areas from 680 nm to 1200 nm are fully obstructed with the use of this set’s “R” filter, while targets originating from H-Alpha and SII regions are permitted passage.

• For a blacker night sky background and unbeatable color balance and separation, the “G” and “R” filters both obstruct undesirable Mercury and Sodium vapor emissions at 580 nm from street lamps.

• These CMOS optimized RGB filters are also suitable for use with older model CCD cameras.

About the Luminance "L" Filter

The obstruction of UV and IR light originating from the extreme non-visible ends of the spectrum is the main purpose of the Baader Luminance "L" Filter. This includes complete blockage of damaging thermal radiation in the infrared, as well as the prevention of blurry stars when working with digital or CCD/CMOS red-sensitive cameras. Meanwhile, all visible spectral areas between 420 nm and 685 nm are allowed to pass at a 98% transmission rate.

About the Red "R" Filter

With the Red "R" Filter, only transmissions from 595 nm to 690 nm wavelengths are permitted to pass, including those of deep sky objects in the H-Alpha line. While there is an intentional overlap between the "G" and "B" filters in terms of spectral emissions allowed to pass, a purposeful gap between the shortest part of the "R" region and the longest part of the "G" region results in the exclusion of a wide range of unwanted light emissions from street lamps and other terrestrial sources. Red "R" filters fully obstruct the NIR and IR from 680 nm up to 1200 nm while keeping maximum transmission of H-Alpha and SII emissions extremely high.

About the Green "G" Filter

Best suited for imaging O-III emission line objects using CMOS monochrome cameras, Green "G" filters transmit wavelengths between 490 nm and 580 nm. Despite the previously mentioned "G" and "B" filter overlap, the crucial H-Beta and O-III emission lines are clearly independent from one another. Although there are no critically important emission lines to be found in the vicinity of 580 nm, Mercury and Sodium vapor street lights do emit from this region. However, thanks to Baader's RGB filter design, these unfavorable emissions are cut off almost entirely, resulting in a darker sky background as well as better color balance and separation.

About the Blue "B" Filter

Of the three Baader RGB filters, The Blue "B" Filter allows the transmittance of the shortest wavelengths (400 nm to 510 nm). This is especially useful for applications involving objects emitting from the H-Beta line (486 nm) such as the Horsehead nebula. Like the "G" filter, the "B" filter also passes O-III emissions (501 nm). When used in combination, these two filters provide double the O-III line energy for unmatched deep sky S/N via extremely high peak transmission.