Star analyser - how?

[bojan]

Due to some health issues I have recently (inner ear inflammation, resulting in severe problem with balace), I was not able to take the spectra of Nova Delphini.. Which is sooo frustrating - especially for the last couple of clear nights here in Melbourne which I know will be over the moment I feel better.

However, I decided to post here couple of images of my way of how to fit PH Star Analyser to the imaging gear (scope, MTO-1100A in this case).

Because with all my home-made gear I am using M42x1mm thread for various adapters, this one is no different.
Star Analyser is mounted in the thread of a larger 3mm thick round plate made of aluminium, with M42x1mm thread at the rim.
This goes into a standard M42 => EOS adapter - which is always a bit thicker/longer (usually 6mm) than necessary, so there is enough thread left for other things, my adapter in this case.
The black ring is made of plastic, and it is here to block reflections from shiny metal surface (I didn't have time to anodise the aluminium ring).

On all this goes the (Canon) camera.. and that's it.

I hope this little post will be of some help to anyone who wants to take the walk on the spectral side..

[Merlin66 (Ken)]

Bojan,
Neat set-up!
There are only two critical issues to be considered when mounting the grating "in ther converging beam" - the distance from the grating to the CCD chip and the orientation of the spectrum across the horizontal axis of the chip.....
The distance should be such to give a plate scale around 10 A/pixel.

[bojan]

Originally Posted by Merlin66

Bojan,
Neat set-up!
There are only two critical issues to be considered when mounting the grating "in ther converging beam" - the distance from the grating to the CCD chip and the orientation of the spectrum across the horizontal axis of the chip.....
The distance should be such to give a plate scale around 10 A/pixel.

Hi Ken,
Both of those requirements are more or less under control here.
The adapter plate is screwed in the thread, but not to the hilt, so it is rotatable (so orientation is adjustable)
And with MTO (when focus stops are removed) it is possible to alter the image scale in relatively wide range (~2.5 ~3x) by inserting the macro-extenders ( like this one) and adjusting the focus (pass the infinity for lens normal working distance of 45.5mm). No need for barlow with Maksutov Cassegrain..

[Rob_K]

Very neat work Bojan, looks a top job! Although you've made me feel positively embarrassed about my rough set-up, with a short piece of female thread glued in an old lens cap.

Cheers -