A new generation - the world-first - galaxy and nebula booster filter intended for shooting not only nebulae, but also galaxies by the use of the transmittance around the near infrared region.
The IDAS GNB filter passes through the Ha and OIII regions in the same manner as of the IDAS NBZ to suppress light pollutions in the visible light regions. Unlike any other filters available in the market, the GNB at the same time passes through the near infrared region intended for shooting galaxies that cannot be shot with any comventional nebula filters. The idea of designing this filter is based on the fact that the near infrared region can be hardly affected by artifical light pollution sources.
We recommend the use with a NIR-enhanced sensor such as IMX585 and IMX464 especially where the GNB is used in a heavly light-polluted location.
The GNB filter will enhance the colorfulness of galaxies when used with a conventional sensor (such as IMX294).
n.b. on halos:
Optical filters such as IDAS GNB and DTD utilizing infrared tend to cause haloing in the NUV and NIR regions. This is because the anti-reflection properties of off-the-shelf cameras' optical systems (oiptical window and sensor cover glass) are optimized for the visible spectrum only, not for the NIR region. Thus, haoling at the camera end in the unoptimized region becomes more apparent, coupled with haloing from the filter itself.
Here is a rough estimation of the magnitude of haoling where the haloing maginute of NBZ (NBZex) is counted as 1:
GNB + IMX294 sensor results in 8.0 times
GNB + IMX585 sensor results in 6.3 times