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TRU-BALANCE FILTERS
SIMPLIFY YOUR IMAGING
Great Filters Just Got Better - Generation 2 Now Shipping!

Astrodon Tru-Balance RGB filters have revolutionized CCD imaging. Their popularity is due to ease-of-use, high optical throughput and great resulting color for galaxies, star clusters and nebulae.  There are two varieties of Tru-Balance filters - E-Series and I-Series.

I-Series filters are designed to approximately equalize the flux of Kodak's Interline CCD detectors, including compensation for the solar photon flux. This means that your RGB color combine weights will be approximately 1:1:1 within perhaps 10%.  This can never be perfect, but it does allow you to take equal time exposures for your RGB data and also just one corresponding dark exposure time.

Introducing Generation 2 True-Balance filters (LRGB2) in April, 2008 in all sizes. This is the first change in Astrodon filter design and fabrication since their inception.  We listened to your requests. 

• 1.25" mounted and 50.4mm diameter
• ~1:1:1 color combine weights for G2V white-point for Kodak Interline detectors (patent pending)
• Equal RGB exposures and one dark time
• Better color separation (spectra)
• Better color rendition of galaxies based upon color theory
• Significant reflection and star halo reduction (see Alnitak image)
• Enhanced contrast for HII regions in galaxies
• Small spectral "gap" to minimize effect of light pollution
• Highest efficiency blue filter with less UV
• Correct "teal" OIII color for planetary nebula
• More parfocal  - thickness 3+/-0.025 mm*
• Parfocal with Astrodon's high-performance narrowband filters  
• Striae-free 1/4 wave fused silica substrates
• 30 arcsec parallelism
• Ultra-hard and durable sputtered coatings

Astrodon filters are known for being parfocal on most systems.  The new thickness tolerance of +/-0.025mm (25 microns) for Generation 2 LRGB fitlers is a factor of 2 better than Gerneration 1 filters, and should be parfocal for systems down to f/3.5, IF your optical system is well color corrected. We have reduced the UV contribution in the lumincance and blue filters for this reason to reduce star bloat  The Clear (no near-IR blocking) may produce bloated stars if your optical system has poor near-IR focus.   Use the near-IR-blocked Luminace filter in this case. The Clear filter is likely a better choice for reflectors, such as Ritchey-Cretiens, rather than refractors or camera lenses.

Spectra

G2V Tutorial for Measuring Color Combine Weights

G2V Database for TheSky6

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