Welcome to Optics Division of ICAS Enterprises!

IDAS/IDASmio NGS1 (ex LPS-D3):
The World First Night Glow Suppression Filter!




M48mm P0.75mm, substrate thickness 2.5mm
mid July



M48mm P0.75mm, substrate thickness 2.0mm
mid June
M52mm P0.75mm, substrate thickness 2.0mm
  AD19.4 drop-in filter for use with M42 drop-in mount adaptor
  for use with ZWO cams (fb 6.5mm) and also IDAS AD19.4 drop-in filter mount
  for use inside the body mount of EOS APS-C DSLR cameras
  for ue inside the body mount of EOS M DSLR cameras
  for Canon EF-EOSR drop-in mount adapter & Meike MK-EFTR-C (EF-R) & MK-EFTE-C (EF-E) drop-in mount adapters - New! Details at: IDAS DRE Filter
  for use inside the body mount of EOS RP cameras
  for use inside the body mount of EOS R cameras
  for use inside the body mount of EOS R5/R6 cameras


Feature 1
The NGS1 is the world-first filter that suppresses both man-made and night glow interferences to the green, orange and red ranges.
Night Glow: OI (557.7nm、630.0nm、636.4nm), NaI (589.0nm、589.6nm)

Feature 2
The NGS1 the successor of the conventional IDAS light pollution cut filters, and thus can suppress the inteference from white LED lights. This filter is also effective against low- and high-pressure sodium lamp pollutions.

Night glow interferenced image (photo taken by Mr. Shigemi Numasawa):

Image ideally processed to reproduce the NGS1:effect

Feature 3
The NGS1 is designed based on the same concept as of the other IDAS light pollution cut filters so that it maxmizes the transfer of the light emissions from various emission nebulae, C2 comae of comet heads and CO+ ionized tails of comet tails as well as coninuous spectrum emissions from space. Its transmittance range is intentionally shifted to the longer wave length side. allowing margins for "the shift tendency towards the shorter wave length side against oblique incidences" typically associated with thin-film interference filters. The NGS1 can almost fully transfer the abovementioned nebular emission lines under the conditions , for example, where the incidence of the parallel flux is kept below 14 degrees, or a lens of the F value 2 or faster (or 1.4 or faster depending on lens) is used before this filter.

Feature 4
The NGS1 filter utilizes the IGAD (ion-Gun AssistDeposition) coating technology which has been applied to our coventional light pollution cut filters. The IGAD technology densifies the multi-layers - the heart of interference filters - resulting in the physical properties that cannot be obtained from the conventional multi-layers.
1) Highly durable thin layers of which hardness equals to quartz glasses. Tremendously improved adherence between the substrate and the multi-layers set.
2) Absolutely almost no aging variation in optical spectral characteristics due to temperature and humidity change as far as used in the regular human living environments.

*This product is an interference filter.  Its spectrum characteristics will be subject to the incidence of incoming light. Please carefully read the following instruction for proper use:
When the NGS1 is placed before the lens:
Use a lens having the light incidence angle of 14 degrees or lower (field angle of 34 degrees or lower).

When the NGS1 is placed between the lens and camera:  (applies to IDASmio filters)

When your camera is equipped with an APS-C image sensor and uses a lens with a *back focal distance of 40mm or greater and F value of two or faster, it is possible to hold down the maximum averaged incidence angle of the incoming light ray against the filter within about 14 degrees. Under the conditions of the above mentioned camera, there will be almost no field angle requirements for the lens to be used.

* Please note, however, that the smaller the diameter of the rear lens element is, the more likely the maximum averaged incidence angle would exceed 14 degrees where the transmittance of nebula emission lines could be deteriorated around the perpheral of the image.

28mm F2.8
50mm F2.0 

*This is NOT the flange focal length..

Examples of night glow images taken and commented by Mr. Shigemi Numasawa

Orange night glow:
"I happened to come across orange night glow in October, 2007 at the northenr sea coast of Niigata Pref. The bearing is north west as the Swan was going to set. I need to be cautious of night glow occurrence at all time esepecially during the shooting."

Gree night flow:
"I came across green night glow in May, 2012 in Utah, USA. Pale green light expands towards South East. I had not noticed it at all during the shooting, but came to find this glow when I opened this image on my laptop at a later date."