I am new in this chat but not new to solar observation at all. I bought several Coronado products in 2004 (MaxScope 40) , 2006 (PST) and 2007 (Solarmax 90 with BF30). All products were bought at OPT, CA.
My MaxScope 40 is used often and is still working like the first day, no rust problems at all!
My Solarmax 90 and BF30 are not used very often but now the BF30 starts to rust (I saw it when I build up the staff for the Mercury transit) and I am looking for a solution. I use the Solarmax 90 with BF30 on a Televue 102iis also with Bino (from Baader)so I like a brighter picture. I know that I could send the rusted BF30 to Bresser (Meade) in Germany to get a new one but I am looking for other solutions (and willing to pay some money) because I read that the new one from Bresser will have a darker output than the old one and rust will be still a problem in the future.
I browsed a lot of cases here in this chat and I know that there are several solution but the information is very scattered in all that different cases.
I found in one case of 2014 (http://solarchat.natca.net/viewtopic.php?f=10&t=12425) the following from Mark:
Another answer in this case is:"To remove the front element of the BF10 there is just a retaining ring that unscrews, a lens spanner will do the job easily.
Maier Photonics do a replacement ITF for the PST here http://maierphotonics.com/656bandpassfilter.aspx which is 100% safe for visual. If you want to use this as a replacement in the BFxx you will need to use a Baader Ha also. Used with a PST mod (with Baader D-ERF) it will work as the D-ERF has excellent out of band blocking on the long and short sides of 656nm.
Alternatively if imaging is your main thing you can use a baader Ha filter (7nm or 35nm), if you wanted to do this visually too a piece of AR coated KG3 used in conjunction with the Baader will block out to >2500nm which is visual safe too."
So instead the whole BF30 for imaging I need just a baader HA and IV/IR filter and for visual an additional KG3 ?"I replaced my rusted BF10 with a Baader 35nm + an IV/IR filter.
It works fine as far as imaging is concerned."
P.S. I do some eclipse chasing since 1976 : https://fotos.web.de/ui/gallery/schoppy