My (second hand) OIII filter arrived today. It’s a filter that blocks all light except for that around the frequency emitted from doubly-ionised Oxygen.
Why on earth would I want such a thing you may ask? I’ll explain later. But for now, I just wanted to share (quite possibly the first ever) the first narrowband kitty photographs.
May I proudly present – my cat in OIII and Ha. (And I suspect that he’s the first cat ever to be photographed through an OIII or a Ha filter).
Here he is again, this time in Hydrogen-Alpha (the wavelength of the light passing through the filter is within 7 nanometers of the peak emission line of excited Hydrogen Alpha atoms):
And here in OIII (I don’t know the exact bandpass of this filter, but I think it’s 30nm wide):
I appreciate that the purpose of these filters may be confusing for now, but I have to pop back to finish off some work and so I’ll write about it in more detail later 🙂