With all the discussion about filters lately, you'll be suprised to discover I've purchased another narrowband filter. I can't afford additional Astrodon narrowband CCD camera filters, but I can afford the Baader prices.

Using my prefered astronomy supplier, Bern at Modern Astronomy, I've got hold of one of the Baader OIII CCD Filters. These are specifically for CCD imaging and they block in the IR, unlike the popular visual filters, where cost is saved on the IR side of things because humans can't see in the infra red.

I know that there is some debate as to the superity of the Baaders over the Astrodons, but getting the 1.25" astrodon OIII would be a serious investment. Whereas picking up the Baader OIII filter is only about 60 quid, so not too bad.

I tried the new filter last weekend, but with the haze and the bright moon, results were disappointing, so I've put the filter away for better coniditions. My first target is to try and get some OII data for the elephants trunk nebula and try to use a synthetic green layer.

Here are a couple of photos of the filter - the Baader OIII oxygen filter looks very professional - the filter holder is particularly well constructed - the whole thing feels very well engineered - much more so than the Astrodon filters, for what it is worth.

baader oxygen OIII narrowband CCD camera filter side viewbaader oxygen OIII narrowband CCD camera filter top view

An interesting demonstration of the general effects of narrowband filters from a human point of view can be determined by simply placing the filter adjacent to the lens on my Canon 350D DSLR and taking a picture of a bright light.

On the left, is a quick photo taken through the Astrodon 6nm Hydrogen Alpha filter, and on the right is the same photo through the Baader Oxygen OIII filter.

my kitchen wirth 350D and Astrodon 6nm Hydrogen Alpha filtermy kitchen wirth 350D and Baader Oxygen OIII narrowband filter