Altair Dual-Band ULTRA Ha / OIII narrowband filter with an adjusted FWHM bandpass of 6 nm.
An individual spectrographic test report is included with each filter - another Altair first. Available in standard 1.25" or 2" astronomical filter sizes. Select size when ordering.
Altair V2 coatings are very effective for LED light pollution, with a deeper blocking factor of OD>6 for wavelengths below 440 nm and OD4.5 for the visual range.
This is the filter for imaging in moonlight or light pollution with a color CMOS camera, or even in dark sky conditions if you want total isolation and control over your channels, narrowband style.
In a process initiated by Altair, each individual filter in our certified range has an individual spectrographic test report with an actual resolution of 0.1 nm, unique to that particular filter. This is not a simulation or the overly optimistic advertising that often appears with foreign filters, such as those that are advertised as having 5 nm FWHM resolution but actually have 6-7 nm FWHM resolution and have generic test reports.
The DualBand Ha/Oiii filter transmits only Ha and Oiii light from emission nebulae, with near-total suppression of unwanted light, with OD4/5 (0.01 %~0.001 %) at most unwanted visual wavelengths. Narrow-band bicolor imaging is a new rising trend in astrophotography, especially popular in areas with light pollution or bright moonlight. First, Altair brought you the TriBand and Quad Band filters, now we have the DualBand Ultra for the most extreme signal versus background performance.
Below is an overview of the wavelengths transmitted by the DualBand filters:
|
DualBand Sii Oii |
DualBand Ha Oiii (this filter) |
|
| Ha |
No |
Yes |
|
| SII |
Yes |
No |
|
| OIII |
Yes |
Yes |
twice the data of OIII when used together!
|
Altair DualBand 6 nm Altair filter features:
- Capture the two main bands of emission nebulae at the same time, while suppressing light pollution, moonlight and airglow.
- Get more data in less time, opening up your imaging window, even in the summer months when it's not quite dark.
- If you have the 6 nm Ultra Ha/SII filter and the SII/Ha version, you can capture twice as much OIII data in each imaging session and combine them for true Hubble SHO-style imaging with a color camera.
- An extremely steep bandpass produces maximum contrast in extreme light pollution conditions: 6 nm FHWM centered on the OIII wavelength of 500.7 nm and 5.5 nm FHWM centered on the Ha wavelength of 656.28 nm.
- Halo suppression . We have received no reports of halos caused by this filter during testing.
- Can be used with mono or CMOS One Shot Color (OSC) astronomical cameras to obtain luminance data.
- It includes UVIR blocking for modified and unmodified DSLR cameras, plus an anti-reflection coating for maximum contrast.
- Best performance is obtained at focal ratios of F4.8 or lower, although it can be used at speeds as high as F3.6, with minimal impact on contrast (conservative estimate: faster speed is possible). Like any dichroic filter, contrast increases as the focal ratio number increases.
- Available in standard 1.25" or 2" astronomical filter sizes. Filters have standard Astronomy compatible filter threads and fit inside Altair magnetic filter holders (with appropriate slider) and standard astronomical filter wheels. Choose the 2" version for use with Altair's Canon / Nikon DSLR to Astro CMOS lens adapters. For Hypercam 183C and 533C or 533M, 585C and smaller sensors, choose the 1.25" filter. For larger sensors, choose the 2" version.
Altair's 6 nm dual band ULTRA filter specifications:
- *1st band, OIII CWL 500.7 nm FWHM 6 nm ~1 nm tolerance, T% 93 % 1 % tolerance.
- *2nd band, Ha CWL 656.28 nm FWHM 5.5 nm ~1 nm tolerance, T% 93 % 1 % tolerance.
- OD4/5 blocking (0.01 %~0.001 %) over most unwanted wavelengths
- 1.85 mm thick optical glass with 30 arc-second parallelism. Parfocal with other Altair filters.
- Si02 "hard" top coat with UVIR blocking and anti-reflective coating for durability.
