Antlia ALP-T Dualband 3nm HA & OIII Filter - 2" - ALPT-DB-3NM-HAOIII-2

This ALP-T, or Anti-Light Pollution Filter, allows a 3nm narrowband transmission from both the OIII and H-Alpha bands!  This model comes in a 2" threaded filter cell, which allows it to be connected to the 2" threaded accessory of your choice, including a 2" filter wheel or filter holder. For f/4 or slower telescopes.

Important!  Do not use this filter for solar viewing or imaging!

Antlia ALP-T Dualband 3nm H-Alpha & OIII Filter - 2"

This dual narrowband filter lets the red H-alpha (656.3nm) and the blue-green OIII (500.7nm) lines through, and is primarily engineered for color cameras when great SNR is desired when taking deep sky images. With an FWHM half-bandwidth designed at 3nm and achieving an optical density (OD) of 4.5 on unwanted wavelengths, it works strongly in blocking light pollution, moonlight, and airglow, leading to enhanced contrast in nebulae images by effectively passing the Ha and OIII emission lines signal only.

Features and Application:

• Passes OIII 500.7nm and H-alpha 656.3nm lines
• Capturing of the two main emission wavebands in the red and blue-green at the same time
• Ultra FWHM 3nm design allows for increasing exposure time and capturing detailed nebulae signal
• Designed to be used primarily with color cameras to capture cleaner data or used as Luminance filter mono cameras to save imaging time
• Recommended to be used with ALP-T Dual Band SII/Hb filter to create images with better SNR( signal-to-noise) and better isolation between the 4 channels
• Suppression of optical density (OD)4.5 on unwanted wavelengths adds signal-to-noise
• Near IR (NIR) is blocked up to 1100nm
• Ideal flat-top and moderate bandpass reducing spectrum downshifts
• Recommended to use the filter with optics f-ratios slower than f/4 for best performance, for optics faster than f/4, pre-shifted highspeed version is a better choice
• Ion Gun Assisted Deposition of double-sided multi-layer coating technology on the double-sided polished substrate making it the most consistent and accurate light pollution suppression filter
• Halo suppression anti-reflective coating is used to minimize halo and internal reflections
• Designed to suppress artificial lighting from Bortle scale 1 to Bortle scale 8
  
• While primarily designed for use with color cameras, the filter is also highly effective with monochrome cameras to save imaging time

Technical Data:

• FWHM: 3nm +0.6/-0.1nm
• CWL (Central Wavelength): Hydrogen-alpha: 656.3nm, Oxygen III: 500.7nm
• Peak Transmission: Hydrogen-alpha: 90%, Oxygen III: 82%
• Blocking: ≥OD4.5 @ 300-1100nm
• Filter Thickness: 2mm+/-0.05mm
• Basic Substrate Optical, Single / Non-glued substrate
• Surface Quality S/D (scratch/dig)= 60/40 (Refer to MIL-O-13830)
• Transmitted Wavefront Lambda/4 or better. Parallelism less than 30 arcsec

Filter Ring:

• 2’’ Mounted (M48*0.75 thread)
• Ultra-thin filter cell to minimize vignetting by maximizing possible clear aperture
• Black Anodized Finish
• Laser Engraving, No Fading