Altair mounted SII OIII DualBand ULTRA 4nm CMOS Filter 2" with test report

Altair mounted SII OIII DualBand ULTRA 4nm CMOS Filter 2" with test report

This filter is designed to be the perfect complement to the Altair 4nm Ha OIII filter. By using both filters you get twice the OIII data you would otherwise - so you can now do proper Hubble pallette style imaging with a colour camera!

This filter delivers what most consider to be the perfect balance of flexibility and transmission. What´s more it delivers 90% transmission over both wavelengths in the same filter, due to a special coating process.
For imaging in moonlight and extreme light pollution as in a major city, with a colour CMOS camera - or even in dark conditions if you want total control over your channels.

The filter transmits only the SII and OIII light from emission nebulae, with almost total suppression of unwanted light, with OD4/5 (0.01%~0.001%) over the majority of unwanted visual wavelengths.
In a process pioneered by Altair, each individual filter has an individual test report, unique to that particular filter, not a blanket test report for the whole batch.

Narrowband Bi-Colour imaging is a growing new trend in astrophotography, especially popular in light polluted areas, or bright moonlight. First, Altair brought you the TriBand and Quad Band filters, now we have the DualBand Ultra for the most extreme signal vs. background performance.

Altair DualBand 4nm Filter Features

Capture the two main emission nebulae bands at the same time, whilst suppressing light pollution, moonlight, and airglow.

More data in less time, opening up your imaging window, even into the summer months when it isn´t quite dark yet. Capture twice the OIII data, whilst obtaining SII to complement the Altair Ha OIII DualBand filter.

Extremely steep bandpass yields maximum contrast in extreme light pollution: 4nm FHWM centred on 500.7nm OIII wavelength, and 4nm FHWM centred on the 671.6nm SII wavelength.

Halo suppression. We have not had any reports of halos caused by this filter in testing.
Can be used with One Shot Colour (OSC) CMOS or mono astronomical cameras for luminance data.

Includes UVIR blocking for both modified and un-modified DSLR cameras, plus an anti-reflection coating for halo suppression. To see the AR coating in action, please see images demonstrating the same filter with and without the AR coating on the bright star, Capella in exactly the same conditions with the same settings.

Best performance at focal ratios as fast as F4.8, with contrast increasing as focal ratio increases. More info about light pollution filter performance and focal ratio here.

The 2" filter has standard M48x0.75mm thread, and fits inside the Altair Magnetic Filter holders, standard 2" filter wheels, plus the Altair Canon / Nikon DSLR lens to astro CMOS adaptors.