Filter fitouts on each of the  iTelescopes varies depending on the role the system plays. Some are Pure imaging platforms while others lend themselves to science, some are a blend of both.

Check here for individual iTelescope information.

iTelescope.Net uses the following filters:

  • UBVRI
  • CLRGB
  • Ha, SII and OIII
  • Some Systems may also have Specialty Filters:  HeII, NIR, EXO, g2, r2, i2, and z2.

Filter Designations for ACP Scripts:

  • Clear
  • Luminance
  • Red
  • Green
  • Blue
  • Ha
  • SII
  • OIII
  • U
  • B
  • V
  • R
  • I

Filter Explanations:

CLRGB filters are UV Blocked Clear, Luminance, Red, Green and Blue - they are typically used for taking artistic pictures of the night sky, although the "Clear" filter is sometimes used with UBVRI as well.


UBVRI are Johnson-Cousins Photometric Filters and represent Ultraviolet (sometimes Uv), Photometric Blue, Photometric Visual, Photometric Red (sometimes Rs), and Infrared (sometimes Ic).  These filters are typically use for scientific research, as they are designed to have the exact same filtering as any other photometric filter of the same type, regardless of brand.  This is to ensure the researchers can duplicate results on multiple telescopes for confirmation of discoveries.


Ha, OIII, SII, HeII, NIR - These are Narrowband Filters, Hydrogen-Alpha, Oxygen-III, Sulfur-II, Helium-II, and Near Infrared.  Narrowband filters usually come in two varieties, 3nm and 5nm, but can come in 6nm and 10nm varieties. (you can see which a telescope uses on the Telescope Information Page).  Most filters allow light for an entire specific spectrum pass through to the sensor.  This is usually around 150-200nm.  Narrowband are designed to drastically reduce the amount of light that passes through to 3nm or 5nm, in an effort to single out these specific channels of light.  These filters are typically used during periods of a full moon, or when imaging emission nebulae.  A good example of this is IC434, which is the bright "red" nebula that you can see as the background for the Horsehead Nebula.  This nebula emits large amounts of Hydrogen so imaging with Hydrogen-Alpha (Ha) filter would prove to have wonderfully detailed results.


Other filters that can be found on iTelescope.Net systems are EXO on T8, which is a filter designed for Exoplanet Research, and on T17, Sloan g2, r2, i2, and z2.  Sloan filters are an alternative form of photometric filters designed for research and have slightly different light spectrum wavelengths than UVBRI.  g2 is in the Blue Spectrum, r2 is in the Green, i2 is in the Red, and z2 is in the early parts of the Infrared spectrum.


The manufacturers of the filters are:

  • AstroDon
  • Custom Scientific
  • Optec
  • Schuller