Sirius --Is it a tuba?

[Conn Buckley]

Again, from last nights outing -- I was practising the akward and difficult tast of trying to focus the camera and nearby happened to be Sirius. I thought Sirius would be too bright and shimmery to get a clean focus but then I got to thinking how would all the colour changing affect an image.
I tried different exposure lengths but still I got this strange effect in each image. It looks like that musical instrument I think it is called a tuba, we have all seen the guy in the Boherbuoy Band with one.
I am sure there is a perfectly simple explanation for this effect. I wondered if any other bright star would produce the same result and tried Betelgeuse, but no luck. Might be to do with the magnitude , colour or both of Sirius. I guess it is caused by light reflection somewhere in the syatem ---- Anybody know what exactly this is?

[Dave Lillis]

Hi Conn,
They are jsut some internal reflections within the scope, not much you can do about it really, next time try putting Sirius in the middle of the FOV, that way they reflections will be in the center with the star.
Were you using the focal reducer at the time ?

[Frank Ryan]

Thats a striking image there Conn, I really like the effect!
The star itself looks massive!