This site existed until I happened upon it after searching for filter reviews:
http://freescruz.com/~4cygni/horsehead/NebulaFilters.htm#STACKING
Copyright © S. Waldee 2014 - All Rights Reserved
Using Eyepiece Nebular Filters for Deep Sky Viewing
By Stephen R. Waldee © 1997-2014 - All Rights Reserved
Nebular filters for visual use, in conjunction with an appropriate eyepiece, make handy accessories for the observer's toolkit. In this article, we discuss the advantages, and drawbacks, of each major type, and comment on various ways that amateurs recommend using them, for good or ill. To quote California amateur astronomer Rod Kaufman, "the number one mistake amateurs make in using filters is that they tend to try them on only one or two objects or with only one or two focal length eyepieces and conclude they do or (as is more often the case) don't work. Big mistake!" This article advocates proper personal testing as the way to learn how a given filter will work beneficially for you.
I see some of my other posts on filters are included as well. It's interesting to see another individual has similar experiences along the lines of my own...
http://freescruz.com/~4cygni/horsehead/NebulaFilters.htm#STACKING
Copyright © S. Waldee 2014 - All Rights Reserved
Using Eyepiece Nebular Filters for Deep Sky Viewing
By Stephen R. Waldee © 1997-2014 - All Rights Reserved
Nebular filters for visual use, in conjunction with an appropriate eyepiece, make handy accessories for the observer's toolkit. In this article, we discuss the advantages, and drawbacks, of each major type, and comment on various ways that amateurs recommend using them, for good or ill. To quote California amateur astronomer Rod Kaufman, "the number one mistake amateurs make in using filters is that they tend to try them on only one or two objects or with only one or two focal length eyepieces and conclude they do or (as is more often the case) don't work. Big mistake!" This article advocates proper personal testing as the way to learn how a given filter will work beneficially for you.
I see some of my other posts on filters are included as well. It's interesting to see another individual has similar experiences along the lines of my own...