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.

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.

What really distinguishes E-Series Tru-Balance filters is their ability to regulate the transition of photons. Within 10%, the RGB color combine weights are about 1:1:1 which means the observor must only take one dark for equal time multiple expores for RGB.

The E-Series is designed for the red-sensitive Kodak full-frame detectors with the goal of equalizing the fluxes, and hence, the signal-to-noise, for the red, green and blue filters.  This simplifies your imaging, because it allows you to take the same length exposure for each color and only one dark frame exposure time.  You will appreciate this since each 16803 FITS file is ~32MB in size.  Within ~10% your color combine weights based upon a G2V (sun-like) star white point should be 1:1:1, making processing much easier.