1 pointGreat captures Ken. Is your 450D modified for AP, or just using the stock filter? I modified mine myself (450D) installing a IR pass filter. Lets in the Ha wavelengths. NOTE: The noise gets rough on exposures above 5min @ ISO 800. 1600 is worse, unless you're shooting say, a comet using 1min exposures. Glad you like it, Have fun and experiment! Tim.