On Sat, Sep 3, 2011 at 9:25 PM, Chrismo <djchrismo@gmail.com> wrote:
thanks for the tips, and the cool picture. stupid question... what's a "standard ND filter"? and what else would you use and what would be the difference?
Baader film is (pretty much) a Neutral Density filter, meaning that it filters most visible wavelengths of light about equally. What you see is a much, much dimmer version (Baader visual film allows only 1/10000th of the light) of about what the sun actually looks like. These are often called "white light" filter. They allow good observation and photos of the surface of the sun, sunspots, and some surface details. There are lots of other types of filters you can get that block, filter, or enhance other wavelengths. For example, a Hydrogen Alpha filter will only transmit the deep red color of light emitted by hydrogen atoms. This allows you to see different types of surface and atmospheric details, prominences (the flame-like ejections from the surface), and other features you can't see in white light through an ND filter. There are also Calcium filters and Helium filters for viewing certain types of surface details. Anything other than ND filters are pretty expensive. You're typically best getting them in a package like the Coronado PST line of telescopes. Jared