A big thank you to everyone that has helped my
on this pet project. Without your contributions my research
could not have been as thorough or enlightening!
Special thanks to Brian and Joanne at
Island Eyepiece & Telescope Ltd. (now gone) for providing me the data
they had on Sirius Optics brand filters, and for providing a
source for Lumicon colour filters, plus the help with all my
Thanks to Ted Ishikawa at
Hutech for providing me data on their IDAS line of filters
as well as sample filters to test,
and to Mia Ishikawa for her fast & courteous online purchasing
Many thanks to Manish and Sarah at
for their great support with Baader Planetarium brand filters as
well as lots of other bits and pieces.
Thank you to Vivien Zhao at
Industries Optoelectronics Tech Co. Ltd. in China for her
help in making an otherwise impossible purchase of rare
wavelength laser pointers possible (and affordable!).
Thanks to Adirondack
Astronomy (now gone) for their quick and dependable supply of
Astronomik brand filters and Lumicon brand filter changers.
Thanks to Stella Song at
Optolong Optics Co. Ltd. for her friendly and courteous
support including providing me with sample filters to test.
Filter Data Sources:
The images of deep-sky filter spectral responses I
used in my analysis were found by me from all over the internet.
Some on manufacturer websites, some on reseller websites, and
some buried in papers that were available online. I have
packaged all the source images together into a single
downloadable archive for reference.
<deepsky filter source images.zip>
The Kodak Wratten and Colour Compensating
filter spectral response data was published in older editions of
the CRC Handbook of Chemistry and Physics (which is what I
have), but is no longer in current editions. I did happen
to find a scanned in copy of this section of the book online in
case anyone is interested.
<transmission of wratten filters.pdf>
http://www.astrosurf.com/buil/filters/curves.htm : A great
site containing deep-sky filter spectral response data as measured by a third
party with a spectrometer. Note that Christian Buil's
measured response of Meade brand filters showed a much lower
response than quoted by the manufacturer, but I have chosen to use the
manufacturer's data in my analysis. His other plots match
fairly well with the responses reported by the manufacturer.
André Knöfel www.astroamateur.de
most extensive collection of transmission spectra
Thomas Klotzbücher www.blackskynet.de (link
now broken) collection of transmission spectra
www.loptics.com/articles/spectra/spectra.html collection of
measured filter spectra
website on filter spectra
Cloudy Nights user "dobrychemik" explanation
on CN, and link to
Google Drive with his reports
I have tried to very carefully and consistently take pictures of
the spectrum of colour filters I have used in my research so
that people can visually compare my filters to what they are
using. The resulting images are below.
Miscellaneous Filter Info Links: