Announcement Baader Narrowband F

Astrodon has updated the "E" and "I" series LRGB filters for SBIG cameras using the full frame "E" chips and the interline "I" chips. An optional clear filter has also been added. The clear filter is UV blocked only. The new transmission curves for these second generation filters are seen below. SBIG is pleased to offer the Astrodon LRGB filters in both 1.25" and 50mm sizes. The 1.25" filters are in threaded cells and fit the CFW9 and CFW10 filter wheels. The 50mm round unmounted filters for the STL series cameras will drop into the standard 5 position internal filter wheel or the optional FW8 eight position filter wheel for the STL cameras.

The E-Series filters are designed to approximately equalize the flux of Kodak's full-frame (E-Series) 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. Choose the E-Series filters for the ST-7XME, ST-8XME, ST-9XE, ST-10XME, STL-1001E, and STL-6303E cameras. Likewise, the I-Series filters are designed to work best with Kodak's interline CCDs found in the ST-2000XM, STL-4020M and STL-11000M cameras.

Compared to the first generation filters, Astrodon Generation 2 filters have:

Better color separation
Better color rendition for galaxies based upon color theory
Significant reflection and star halo reduction
Enhanced contrast for HII regions in galaxies
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 and near-IR 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 filters is a factor of 2 better than Generation 1 filters, and should be parfocal for systems down to f/3.5, IF your optical system is well color corrected. Astrodon has reduced the UV contribution in the luminance 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 Luminance filter in this case. The Clear filter is likely a better choice for reflectors, such as Ritchey-Chretien, rather than refractors or camera lenses.