Astrodon LRGB Gen2 I-Series Tru-Balance Filter Sets
Astrodon LRGB Gen2 I-Series Tru-Balance Filter Sets are designed to approximately equalize the flux of Interline CCD detectors (formerly Kodak), including compensation for the solar photon flux. The I-Series filters compensate for the lower red response of these Interline detectors affecting the design of the Green and Red filters. The Luminance and Blue filters are the same as those in our E-Series. This means that your RGB color combine weights will be approximately 1:1:1 within perhaps 10% for equal length exposures. This can never be perfect, but it does allow you to take one exposure time for all of your RGB data and therefore, only just one corresponding dark exposure time. Again, this saves you precious imaging time and thus, simplifies your imaging.
- Set includes Luminance (NIR/UV-blocked colorless), Red, Green and Blue filters
- 1.25″ mounted, 31, 49.7 mm dia.
- 3 +/-0.025 mm single 1/4 wave fused silica substrate before coating
- 30 arcsec parallelism
- ~1:1:1 color combine weights for G2V white-point for Kodak Interline detectors
- Equal RGB exposures and one dark time
- Better color separation (see spectra)
- Better color rendition for galaxies based upon color theory
- Significant reflection and star halo reduction
- Spectral “gap” between green and red filters to reduce the effects of light pollution
- Highest efficiency blue filter with less UV
- Correct “teal” OIII color for planetary nebula (OIII signal >97% in blue and green)
- Parfocal with Astrodon‘s high-performance narrowband and near-IR Luminance filters
- Ultra-hard and durable sputtered coatings coated to the edge of each filter
- Proudly made in the U.S.A.
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A common question: Should I get E-Series or I-Series LRGB filters?
The answer is that it depends on your camera sensor. Progressive Scan camera sensors ( including both Front Illuminated and Back Illuminated sensors) use the E-Series LRGB filters. Interline Transfer sensors should use the I-Series LRGB filters. Finding out what type sensor your camera uses can be difficult. This information is not often included in the specifications or even the manual. So it is best to check with the sensor manufacturer. If you absolutely can’t find out, then go with the E-Series and you will be fine.
FLI has put out a convenient list that specifies which type of sensor is in their camera. Since you usually know what sensor is in your camera (and different camera brands often use the same sensor) , this handy list can be used for other camera brands as well. But again, checking with your camera manufacturer and asking if their sensor is Front Illuminated, Back Illuminated, or Interline Transfer is your best bet.
“I would like to take a minute to comment on the 50mm Gen 2 filters that I have installed in my Apogee 16803 camera. These filters set a new bar for performance … they have a huge color gamut and best of all, there isn’t a trace of reflection even when shooting 15 minute subs at the Pleiades.
The total color response can be seen in the M33 sample … note the abundant HII regions, the strong blue response, and the brilliant yellow of the star. The superior color response isn’t subtle … it’s obvious … and all this with LRGB … no narrow band needed! These filters are a joy to work with. Major kudos.”
“For several years I happily used a set of common filters under the assumption that there was nothing unique about other filters on the market. I was wrong! Since switching over to Astrodon filters, the color fidelity of my pictures has improved dramatically! Not only do they reduce or eliminate the need for color balancing during post-processing, their precision bandwidth cut-offs result in more vivid colors and the H-alpha filter has helped me surface structures my previous filters simply did not allow my camera to capture. Astrodon filters are essential tools for serious astrophotography.”