Standard filters

[Inka]

Does anyone know what a "standard filter" is in Asronomy? Is it the same as a coloured filter? does anyone know any good webpages explaining this?
Thank-you for your help
Inka

[Inka]

Is this a really stupid question?

[2inquisitive]

I really don't know what a "standard filter" would refer to for sure. I might guess
either a skylight filter (if you have a Schmidt Cassegrain telescope) or possibly
a neutral density (ND) filter. Some like to use a skylight filter mostly to prevent
debris or insects from entering a SC telescope while the accessories are being changed
or removed. It is supposed to help some with light pollution, but I can tell very
little or no difference. A neutral density filter is a very common and almost essential
filter to use while viewing the moon. The moon can be so bright through a telescope
that it hurts your eye and the ND filter reduces the brightness. You may already know
all this, but I don't know how new you are to astronomy.