Altair DualBand ULTRA 4nm CERTIFIED CMOS Filter 2" w test report

Here is a great review of this product! Thank you to Cuiv, The Lazy Geek

Altair Dual-Band ULTRA Oiii / Ha nebula filter with high resolution spectrographic test report.

For imaging in extreme light pollution, E.g. in a major city, with a colour CMOS camera. 

This filter transmits only the H and Oiii light from emission nebulae, with almost total suppression of unwanted light, with OD6 (0.0001%) over the majority of unwanted visual wavelengths* for ultimate contrast. 

In a process pioneered by Altair, each individual filter in our certified range has an individual spectrographic test report with 0.1nm true resolution, unique to that particular filter. This is not a simulation, nor the overly optimistic marketing you tend to get with foreign filters - such as those advertised at 5nm FWHM but which actually have 6-7nm FWHM, and which have generic test reports.

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 light pollution suppression.

Altair DualBand 4nm Filter Product 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.
• Extremely steep bandpass yields maximum contrast in extreme light pollution: 4nm FHWM centred on 500.7nm Oiii wavelength, and 4nm FHWM centred on the 656.3nm Ha 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 F4.0, optimised at F4.8 or slower, with contrast increasing as focal ratio increases. Faster than F3.5 requires an Altair Pre-Shifted filter (please get in touch for more info). 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, plus the Altair Canon / Nikon DSLR lens to astro CMOS adaptors. 

Altair 4nm DualBand ULTRA Filter Technical Specifications:

• 1st band, Oiii CWL500.7nm FWHM 4nm tolerance ~0.5nm, T% 88%~91%
• 2nd band, Ha CWL 656.3nm FWHM 4nm tolerance ~0.5nm T% 90%~94%
• OD6 (0.0001%) from 200-760nm (visual wavelengths), and OD4.5 (0.003%) average from 800-1100nm (IR wavelengths) for the ultimate contrast. *Based on a test of 10 random samples in  batch 09-2023.
• 1.85mm thick optical glass with 30 arc sec parallelism.
• Si02 "hard" overcoat with UVIR Block and Anti-Reflection Coating for durability.

Q: How do OSC Narrowband filters work? Altair OSC narrowband filters work by isolating the primary nebulae emission zones in the red and blue wavelengths, and separating them into two main "zones" with a wide separation for easy capture with a colour camera - all in one exposure! Not only is capture more convenient with one filter, but processing is easy too, thanks to the wide separation of the green/blue and red "zones". Light pollution control is extremely effective and even LED light pollution is significantly reduced.

 

Q: What does "DualBand" mean? Here's an article explaining what a DualBand light pollution filter is. 

Q: What cameras are compatible with DualBand light pollution filters? Sensitive OSC or "One Shot Colour" CMOS cameras like the Altair Hypercam capture light from emission nebulae very efficiently, and allow them through the Bayer matrix, and are mostly used with Dual Band filters. These filters also work with DSLRs or in fact any colour camera! 

PLEASE NOTE: Demand for this product is very high. We sometimes temporarily suspend order to allow production to catch up. When we catch up with backorders we will re-enable ordering. We apologise for any inconvenience. Altair and Dealers reserve the right to change product specification and price without notice.