About this product
Antlia ALP-T Dual Band H-Beta/SII 5nm Ultra-Narrowband Filter
The ALP-T Dual Band 5nm Highspeed Filters are further optimised to work with high-speed imaging systems by shifting the passband and centre wavelength slightly. Using these highspeed filters between optics f-ratios f/2.2 and f/3.6 shows much stronger contrast in nebulae imaging compared to the standard version.
For optics f-ratios slower than f/3.6, the standard ALP-T Dual Band 5nm filter is highly recommended.
For One Shot Colour CCD / CMOS / DSLR Imaging - Simultaneously Capture H-Beta and SII Data
The ALP-T dual band 5nm SII&Hb filter is a dual line-pass filter, which lets the deep red Sulfur-II line and the blue Hydrogen-Beta line through and is used with one-shot colour (OSC) cameras such as DSLRs or astronomical OSC cameras. It is a significant addition to the popular Antlia ALP-T dual band 5nm Ha&OIII filter and enables false-colour images and narrow-band nebula images using OSC. When capturing data with this filter, the nebulae are recorded with greater contrast against the background than without it.
Combining these two dual-band filters allows extreme narrow-band images with OSC cameras by capturing the spectral data from 4 channels, i.e. Ha/OIII/SII/Hb. The spectrum of these four channels can be separated and recombined into various colour palettes in your post-processing. The resulting images can be used for luminance contrast enhancement of traditional RGB-balanced images or creating images in various popular false-colour palettes such as H-O-Hb, S-H-O, H-S-OHb, H-O-O etc.
IMPORTANT: These filters are NOT designed for observing or photographing the Sun. DO NOT use these filters to observe or photograph the Sun. If you do it will result in permanent eye damage!
- High transmission of H-Beta and SII emission lines (peak transmission 90% for SII & 85% for H-Beta)
- FWHM: SII 5nm, H-Beta 5nm
- Engineered specifically for use with DSLR, CMOS, and CCD colour cameras
- Designed to suppress artificial lighting from Bortle scale 1 to Bortle scale 8
- 36mm unmounted or 2" mounted filters
- 36mm supplied with a B4836 filter holder enabling it to fit a 2" / M48x0.75 filter thread
- 2" mounted filter has an ultra-thin filter cell to minimise vignetting and maximise clear aperture
- 300-1100nm ≥OD4.5 blocking of unwanted wavelengths for improved signal to noise
- Near IR (NIR) is blocked up to 1100nm
- Extremely steep bandpass edges minimise internal reflections
- Ideal flat-top and moderate bandpass reducing spectrum downshifts
- Supplied in a protective plastic case with EVA foam lining
- 2mm+/-0.05mm glass thickness
- Fine-optically polished on both sides
- Ion Gun Assisted Deposition coating technology making it a highly consistent and accurate light pollution suppression filter
Blue Line - Represents the transmission curve of the filter.
The Major Emission Lines of Nebulae: H-α (656.3nm), H-β (486.1nm), OIII (495.9nm) and OIII (500.7nm)
The Major Emission Lines of Artificial Light Pollution: Hg / Mercury (435.8nm, 546.1nm, 577nm and 578.1nm), Na / Sodium (598nm, 589.6nm, 615.4nm and 616.1nm)
| ||SII ||H-Beta |
|FWHM ||5nm ||5nm |
|CWL (Central Wavelength) ||672.4nm ||486.1nm |
|Peak Transmission ||90% ||85% |
|Blocking ||≥OD4.5 @ 300-1100nm |
|Filter Thickness ||2mm+/-0.05mm |
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