Clear nights are few and far between in the Midwest throughout Winter. When they come along, I just want to get out and image. This night was no exception. So I decided to do a little experiment to see how the IDAS NB1 filter by Hutech would perform in the most impossible conditions.
I’ve been using this filter since last April, but really only in good conditions. I’ve been impressed with the reduced imaging time required to capture decent contrast throughout the last 7 months, but I wanted to see just what it’s giving me. On a night like this, my Optolong L-Pro or CLS filter wouldn’t allow me to even start to image. The blowout and vignetting would be unbearable even with short exposures.
The bandpasses aren’t as narrow as something like the Radian Tri or Quad-band filters, but at 1/4 the price, it’s a nice compromise. While the SII only comes in around 40% transmission, the Ha, Hb and OIII lines are all passed at about 95%. Living in a Bortle 8/9 and having to drive 100+ miles to real dark skies, my only options for producing quality images are a filter like the NB1, or true narrowband imaging with a mono camera.
I imaged for a couple years with a CLS filter that would perform greatly if I lived just a bit further out from the bright lights of Chicago, but I was limited to brighter objects and many, many hours of integration from shorter exposures. My images really jumped to the next level with the addition of the NB1 filter. In full disclosure, I obtained the ZWO ASI071MC Pro camera at the same time. That didn’t hurt either.
One thing that surprises me with this filter is star color. While I can obviously pull out the reds and blues well in the veil nebulae, I wasn’t expecting any real star color with this filter. Surprisingly, the red stars really came out with my reflector, but the blues were just blown out into white. Now, having moved to a quality APO refractor, I am seeing the blue stars as well. I thought to get any real star color I’d have to layer in several shorter exposures through my L-Pro filter, but I’m not finding that to be the case.
While I didn’t capture any great images last night, I was surprised with the data I pulled in with some very short integration time. This is 2 hours on the Bubble Nebula region and 1 hour and 21 minutes on the HorseHead and Flame nebulae from Bortle 8/9 skies, with a full moon and adjacent to LED Christmas lights.
27×180″ 
40×180″
I’m continuing work on M42 in better conditions with a surprise there as well. In my annual attempts, I had never captured any of the dust surrounding the Great Nebula in Orion. I figured it was a lost cause due my location after collecting 7 hours of integration. I certainly didn’t expect to capture much of it with the NB1 filter. I had set aside 4+ hours with the L-Pro filter in addition to 4 hours with the NB1 filter to capture the full range of reds and blues and the surrounding dust. The image below is 4 hours of NB1 data without any L-Pro data. Keep in mind, this is still from Bortle 8/9 skies with much of the data shot low on the horizon as I have to deal with trees in my Southern sky.
If you live in a very light polluted area, and don’t have $1000 to drop on a filter, I think you’ll be very satisfied with the tri-band NB1 filter for $240 (48mm version). I won’t be out willfully imaging next to the full moon within feet of hundreds of twinkling LED lights any time soon, but I think this little test night proved the worth of this filter several times over.
AstroHutech also offers and NB2 (HA and OIII) dual pass and an NB3 (Ha and SII) dual pass filter for around $200 each if you’re looking for something more specific.
Clear Skies, Bleary Eyes – KA
Katorella Astro 