I’m after recommendations for a 2” O-III filter for visual, using my 6” f12 Refractor.
I have an Orion Ultrablock UHC that works quite well on some objects....the Dumbell neb is like a cotton ball with it, and barely there without it....so thumbs up from me. A google search reveals Baader seems to make filters for Celestron and Orion, so the Baader 10 nm 2” looks good, as does the Astronmik at quite a bit more cash outlay. Any others?
I have a filter drawer system on a 2” GSO dielectric diagonal so changing filters is a breeze.
Matt
I used to have a 2” Baader one years ago that I believe was 12nm and that worked wonders in my Melbourne backyard.
I eventually downsized to a 4” for my primary visual scope and got the planetary/Luna bug
I've just this morning taken delivery of 1.25" and 2" OIII Lumicon filters from EyepiecesEtc.com. With the Brisbane weather looking like being wet until Easter I won't be able to give an opinion for a while yet, but they've had good reviews.
DGM Optics do a NPB filter which picks up OIII as well as Ha and Hb - it's a great filter which I use quite a lot. Tends to give a more orange rather than green cast to the view, which I prefer over the green of a straight OIII.
Here's a comparison chart done by Phil Harrington from Astronomy magazine comparing a lot of different brands/style of filters. The article is pretty old and some of the filters may have been upgraded/discontinued since then, but it might be worthwhile reading.
... in that order. However Lumicon has gone through a generational change so I cannot comment on the current offering. Thousand Oaks has incredible jet black background with white nebulousity (eta carina nebula) but I feel it would benefit from a larger aperture than the 10.1" f6.4 Newtonian I was comparing with the other on.
I am also partial to the original Tele Vue O-III Bandmate filter as it is a bit broader that the three above and gives a very natural background with more stars visible but also plenty of nebulousity. This filter has now been replaced with the Type 2 version by Tele Vue in a partnership with Astronomik but I have not used the latter for comparison.
Don Pensack, who runs EyepiecesEtc, made a brief comment on the new Lumicon OIII Gen 3 filters on the Cloudy Nights forum and spoke highly of them (prompting me to part with a largish wad of cash).