ANTLIA ALP-T "gold" Dual Band 5nm Filter- 36mm


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ANTLIA ALP-T "gold" Dual Band 5nm Filter- 36mm - HIGH SPEED version for f/2.2-f/3.6 (unmounted, but with a B4836 2" filter adapter included)

The ALP-T Dual Band 5nm Highspeed Filters are further optimized to work with high-speed imaging systems by shifting slightly the passband and center wavelength.
Using these highspeed filters with optics between f/2.2 and f/3.6 shows much stronger and more contrasted nebulae imaging compared to the standard version.
For optics f-ratios slower than f/3.6, the standard ALP-T Dual Band 5nm filter would be a better fit.
Meanwhile, if you seek the best possible performance with any optics faster than f/2.2, the highspeed version would still be the best choice, however keep in mind that the blue shift data by the computer simulation indicates narrowband filter shifts its bandwidth to shorter wavelengths with faster optics than f/2, transmission at the emission wavelength may decrease perhaps 15%-20%.
Although the Antlia ALP-T highspeed filter has similar transmission rates reduction in the H-a and OIII when the filter is used on fast optics, based on current standard version users’ data, it is evident that the filter still has high performance of increase in emission nebula contrast and minimized halo.
The price of the highspeed version is the same as that of the standard filters, but doubles the benefits for the high-speed optics users.
Worth mentioning that Antlia inspected and measured their products piece by piece with an Agilent Cary’s professional spectrophotometer with a resolution/slit width up to 0.2nm, which make us provide highly reliable and consistent products to you..
The Antlia ALP-T dual band 5nm series filter is a dual line-pass filter that was designed to be used primarily with one-shot color (OSC) cameras such as DSLR's and astronomical OSC cameras. It can also be used as a narrowband filter for monochrome cameras to save imaging time.
The advanced multi-coatings on our ALP-T ultra dual band filter effectively isolate the red Ha and the blue-green OIII lines light from emission nebulae, with almost total suppression of optical density
(OD)4.5 of unwanted wavelengths from light pollution, moonlight, and airglow. The result is that our ALP-T dual band 5nm filter creates a superior signal-to-noise ratio and better contrast in your images.
The filter enables the capture of the two main emission nebulae bands at the same time, whilst suppressing unwanted light pollution. 
It enables you to capture cleaner data and reduces the post-processing efforts to isolate faint details from the background light pollution.

Application and Performance:

  • Designed specifically for fast astronomy optics between f-ratios of f/2.2 and f/3.6
  • Engineered for use with DSLR, CMOS, and CCD color cameras
  • Suppression of unwanted wavelengths (optical density of (OD) 4.5) improves signal-to-noise ratio
  • Extremely steep bandpass edges minimize internal reflections
  • Ideal flat-top and moderate bandpass reducing spectrum down shifts
  • Ion Gun Assisted Deposition coating technology on the double-sided polished substrate making it the most consistent and accurate light pollution suppression filter
  • Designed to suppress artificial lighting from Bortle scale 1 to Bortle scale 8
  • Near IR (NIR) is blocked up to 1050nm

Technical Data: 

Hydrogen Alpha

Oxigen III

FWHM 5nm 5nm
CWL (Central Wavelength) 657.8nm 502.2nm
Peak Transmission 88% 82%
Blocking ≥OD4.5 @ 300-1050nm ≥OD4.5 @ 300-1050nm
Filter Thickness 2mm+/-0.05mm

Filter Cell (specifications for cell mounted filters only):

  • 2” (M48*0.75)
  • Ultra-thin filter cell to minimize vignetting by maximizing possible clear aperture
  • Black Anodized Finish
  • Non-Fading Laser Engraving

Available Sizes:

  • Mounted: 2” (2mm thickness)
  • Unmounted:Dia 36mm (2mm thickness)

Not Recommended:

  • Solar Observing and imaging
  • Visual observation
      Serious eye damage will result if you fail to observe the warning.


You will see the same images on the manufacturer's website. The difference is that we decided to slightly improve the images in Photoshop, however whilst these images below had been improved, on the other hand we also had to reduce the resolution due to the image size limitations on our website.

Below image was taken via the new HIGH SPEED version of the ALP-T filter.

Below images were taken with the normal (original) version of the Alp-T, not the high speed version. We left them here for now only for reference.

ANTLIA ALP-T "gold" Dual Band 5nm Filter- 36mm