Askar has introduced the Askar Color Magic Ultra E-Series Filter Set, which features two dual-band filters and gives OSC users the creative freedom of a monochrome camera. By pairing the 4nm Ha/OIII filter with a 4nm SII/OIII filter, this package allows OSC (one-shot color) users to achieve stunning Hubble Palette-style images without switching to a mono camera.
Narrowband imaging has been favored by monochrome camera users and one-shot color (OSC) users alike. Combining narrowband filters together (for monochrome camera users) or shooting through a dual-band filter (for one-shot color camera users) has allowed us astrophotographers to photograph our favorite deep sky targets through our light-polluted environment. Monochrome cameras have always had the upper hand in terms of resolution, sensitivity, and post-processing creativity thanks to the separate Ha, SII, and OIII narrowband filters that are so commonly used with mono cameras. OSC cameras, on the other hand, tend to be the best choice for those first jumping into the hobby. While convenient, the dual-band filters often used with OSC cameras don't allow the same creative freedoms as three separate narrowband filters... Until now.
Click to Enlarge Image
What is Narrowband Imaging?
Narrowband filters allow astrophotographers to cut through heavy light pollution by only passing specific, narrow wavelengths of light. This is especially useful for imaging bright emission nebulae like the Orion Nebula, Heart Nebula, or Pacman Nebula, where Ha (Hydrogen-alpha), OIII (Oxygen-III), and SII (Sulfur-II) emissions are extremely abundant. (See Melotte 15 image above.)
A traditional dual-band filter passes two wavelengths, usually Ha and OIII. The Ultra E-Series, however, goes a bit further and introduces the E2 filter that passes SII and OIII. This second filter gives OSC users access to all three wavelengths (Ha, SII, OIII) as well as the ability to process the data just like one would process data from a monochrome camera and individual SHO filters.
Why OSC Users Struggle with Ha/OIII Alone
Most astrophotographers who use OSC cameras with a Ha/OIII filter end up with data dominated by Ha signal, resulting in mostly red images that completely conceal the OIII data collected through the filter. While semi-advanced channel separation techniques can help, they can be time-consuming and still fall short of delivering the vibrant oranges, greens, and blues of a full SHO palette.
“With nearly a decade of astrophotography experience, I’ve always leaned toward monochrome when I wanted the highest quality SHO image. That was until I tried the Askar E-Series.” - Teagan
Before we look deeply into the data collected through the Askar E-Series filter, let's dive deeper into filter specifications.
Filter Specifications and Build Quality
These are 2-inch filters with standard M52 threads, making them compatible with today’s most popular filter wheels, drawers, reducers, and field flatteners. They also fully support full-frame sensors with a 44mm sensor diagonal.
E1 Color Magic Filter
- Type: Dual-band Ha/OIII
- Bandpass: 3.7nm (Ha) / 4nm (OIII)
- Wavelengths: 656.6nm (Ha), 500.7nm (OIII)
- Excellent light pollution blocking, even under a gibbous moon.
- Extremely narrow bandpass for higher contrast and fine detail.
Click to Enlarge Image
Click to Enlarge Image
E2 Color Magic Filter
- Type: Dual-band SII/OIII
- Bandpass: 4nm (SII) / 3.7nm (OIII)
- Wavelengths: 672nm (SII), 500.7nm (OIII)
- OIII bandpass matches the E1 for seamless data integration.
Real-World Testing
We had to put these filters to the test under a full moon / Waxing Gibbous. We dedicated 34 total hours of exposure time on the Butterfly Nebula near the bright star Sadr. This area is full of emission nebulae and would be the perfect test to see how well these filters can replicate a monochrome SHO data set. We used the following equipment:
- Askar FRA500 at f/3.9
- ASI2600MC Air
- ZWO EAF & CAA
- ZWO AM5N mount
Over 34 total hours of exposure time were captured using 900s subframes over a period of 5 nights. Below you can find a basic histogram stretch of each filter’s data set.
E1 Ha/OIII Data
- Crisp, clean dataset with very strong Ha signal.
- OIII is present but overshadowed by Ha in a simple stretch, but very prominent when separated into RGB channels.
- Great starting point for HOO-style images.
Click to Enlarge Image
Click to Enlarge Image
E2 SII/OIII Data
- Clear mapping of SII regions around the Butterfly nebula, but also present locally throughout the entire frame.
- Abundant OIII spread across the field.
- Contains crucial data for achieving a rich and balanced SHO composition.
SHO From OSC
By combining the Ha from the E1 with the SII from the E2 and blending OIII from both, we were able to process a true SHO Hubble Palette image in PixInsight just as we would with a monochrome camera. We have gone through the specifics here in a bit more detail in our full video review on this set of filters.
Final Thoughts From Teagan
In all of my years imaging with an OSC camera, I haven't been able to achieve these results with an Ha/OIII filter alone, and being able to transform my images from an HOO style image to a legitimate SHO image has been revolutionary. I have always been a dedicated monochrome camera user, but now I am excited to move forward with further product reviews with the 2600mc-Air and the Color Magic filters from Askar. If you currently image with an OSC color camera and you're looking to transform your images into the gorgeous Hubble palette style images you see from monochrome cameras, then I highly recommend the Askar Color Magic Filters. Askar does offer the C, D, and E-series color magic filters to meet any of your narrowband imaging requirements, with the E-Series being the narrowest of the line.
Learn More
Interested in diving deeper into the world of astronomy? Check out our AstronomyHub for a wealth of articles, guides, local resources for planetariums and observatories near you, and more to enhance your stargazing experience.
