To Paul Kanevsky:

A quick question on CCDI.

Would CCDI be suitable for collimating a Schmidt camera. I have a Celestron C8, with a Hyperstar lens and a SXV-H9C. The resulting image scale is 3.5 arcsec/pixel (f/1.8). Is this image scale is too coarse for CCDI?


Thanks


Colin

Hi Colin,

3.5"/pixel will be too small. Under good seeing conditions, the FWHM will be a lot less than one pixel, so the star profile will not be determined accurately.

You can try collimating with a slight defocus, which will spread the star over a few pixels. This works well with most common optical systems. Some really fast ones have been reported to distort the stars too much when out of focus to make measurement possible. I would suggest you give it a try. Defocus very slightly to get FWHM of 1.5 to 2 pixels.

Remember to set the Bayer Matrix camera in Settings->Default Image Properties menu if you'll be using the raw frames from your camera.

Regards,

-Paul

Paul;

Thanks for the info. I will give it a try later this month and let you know what the results are

Best Regards,


Colin

Any update on this?

I have a Hyperstar and wonder how well CCDI will work with it. The miscollimated star images at edge of field are cresent shaped (with the horns towards the centre) rather than radially elongated.

Regards
Mark