I have been in contact with the President of Omega Optical in the U.S. concerning the ebay store he runs.
Omega Optical are a producer of all types of filters for all sorts of applications in Industry.
As with most large orders there are always a overrun of material.
With this in mind Bob Johnson makes available at a greatly reduced cost the broadband and narrowband filters that we know as O111, HB etc. At the current exchange rate a 2" O111 HB filter cost del to my door $73AUD. The 1 1/4" is approx $59AUD.
I have just recieved mine and the difference between having the filter and not is amazing. Nebulas that look good in the E/P just jump out at you with more detail.
These spectrum specific filters work better as aperture increases.
Try out the ebay site at bjomejag or send your enquiries to
bjomejag@sover.net. Website is
www.omegafilters.com 