Hello group ,
i just downloaded ccdin2 and i tried it with a test image of 600sec that i had of m27 a few day ago...
I thing i got an awful result (for my sct?)or am i doing something wrong?
The set up i used was (from scope to camera) C11 - OPTEC TCFS - PYXIS ROTATOR - AO8 -CFW8A - ST 10 XM.
And the result i got is in the attachement...
This one means that my telescope is way off collimated or something else?

Thanks in advance
Nikos

test.JPG (21 KB, 34 downloads) test image

Hi Nikos,

To measure collimation properly, you'll need to take a much shorter exposure (10-30 seconds maximum) and take the exposure of a well-populated star field. At least 150-200 well spread-out stars are needed to measure this properly (your image contains 70 stars according to the display).

The very high FWHM value is also telling me that the telescope was not in focus, seeing was really bad, or the telescope was not cooled down to ambient temperature. With proper collimation and focus, you should be able to achieve around 2 arcseconds FWHM on most nights.

Regards,

-Paul

Thanks Paul
i will try next available night and i will let you know...

Nikos

Hi Nikos,

You may also want to try the single defocused star collimation viewer in CCDInspector: this makes it easier to do a quick check since you don't have to focus, and you don't need to find a rich starfield with a lot of stars. A single bright star defocused into a doughnut will do.

Regards,

-Paul

Thanks
I am going to try this first

Nikos

One more question should i input anything in the software or only a fit image from ccdsoft and it takes automatically the focal lenght etc...?

Thanks

Just make sure CCDSoft is configured with the proper focal length for your system, and you will not need to change anything in CCDInspector:




Regards,

-Paul

Hello Paul
i made my first try.
The first night was at about 1.8 but i tried for something more and i destroyed it.
Should i stay around 2.

In every image the value change 2-3 (values ) is it from the seeing

Thanks
Nikos

Hi Nikos,

Are you talking about collimation error values? If so, the error between 1.8 and 3 is very good. The values will vary a bit due to seeing, but a collimation value of less than 5 is usually very good.

Regards,

-Paul

Hello Paul
i retry today the value is around 3 but the image of the defocused star dont look good at all...What you think?

test.JPG (144 KB, 34 downloads)

and one more

test2.JPG (151 KB, 30 downloads)

Hi Nikos,

Please send me one of the images as a FITS file to:

paul [at] pk.darkhorizons.org

and I'll check it out. It certainly doesn't look anywhere close to collimation error of 3!

Regards,

-Paul