[sheeny (Al)]

Originally Posted by Starkler

Very interesting. How do you calibrate the differing sensitivity of the cam vs wavelength of light?

Ah! Excellent question... That's somewhere in the learning curve ahead of me... I have seen it mentioned in the tutorials, but as for details... I don't know yet.

Originally Posted by [1ponders]

Wow, keep 'em coming Al.

How did you get your focus Al? It seems the spectrum is a bit soft. It would be interesting to try it with the mono cameras and colour filters as well (or without). You might find you get a sharper result. Top effort though!

I focused with my prototype Bahtinov Mask. I doubt I could've got the focus much better actually... I think the softness is probably the seeing - it wasn't that flash and Antares was maybe only 20°-30° elevation at the time. I also stacked about the 30 best frames, but no sharpening, wavelets, etc. I'm not sure if that's the best way to go, or simply pick the best frame. After a quick look on the Staranalyser forum, it seems others are stacking too, so I did that just cause I'm used to doing that on other photos.

The Achernar spectrum you may notice is very narrow in the red part of the spectrum and wide in the blue...... I'm not sure why that is, but if I had to guess I'd say the focus was OK, but the blue light was being scattered more. I did put my f/6.3 FR in the train for that one though, so I might have to keep an eye on that... maybe that's the source of the blue spread?

Originally Posted by Terry B

I would have thought that no filters makes more sense as you would get only part of the spectrum with each filter.
When I saw the colour image I wondered how it would work as different parts of the spectrum will be covered by each colour on the bayer array. I suppose as long as there is enough crossover and you are not trying to measure the absolute intensity at any particular frequency it will work with a colour sensor.

From the very little I have read, there is more to do in calibrating a colour image for the response of the camera than there is for a mono camera. Ultimately I plan to use the DMK, but for starters I'm playing with the ToUcam sinc eI figure the colour will help me to identify what I'm looking at in the spectra. When I find my legs I'll probably go mono just cause it'll simplify the process a bit.

Originally Posted by [1ponders]

I was thinking of the idea of no filter as well Terry, but I figured using an LRG combined tricolour imagine you could still get the desired result after combining the separate channels but the resolution should be better. It would be interesting to try. Of course the colour weight would have to be right.

Hmm. I don't know. You would have to have overlap between the filters, otherwise you'll miss sections of the spectra, but that you'll need to correct for the overlap... I suppose that's what you have to do with an RGB camera anyway...

I am fascinated by the length of the IR end of the spectrum... there's heaps there! It is no wonder a UV/IR filter has such a positive effect on images!

It's all baby steps at the moment.

Al.