Rotational periods and image scale

Hello all,
I have a question regarding how long I can image before rotational smearing occurs. Is there a formula you can apply for each planet? Does the image scale you capture at have any affect on this? (i.e. using a 2x Powermate or 4x on my C11.) How about a reference for rotational periods for all the planets? I ask because the seeing is rather bad here in Omaha Nebraska and I can only use a few frames from each capture.
Help a brother out...

Bryan Gumm

Hi Bryan.

Yes, image scale has an effect - the smearing is only seen when features move laterally more than the size of your pixels, so the larger the image scale the faster this will happen.

It depends on your focal length and the size of the pixels in your camera. Rather than try to work out a formula I took the easy way out and just compared first & last frames from capture sessions to see if I could see any rotation.

Using a camera with 5.6 micron pixels and a focal length of 6000mm I decided that I could tolerate 1 degree of rotation.

For Jupiter that means capture sessions must be no more than 90 seconds, and for Mars it comes to about 4 minutes.

YMMV

regards, Anthony

Thanks for the great advice. It helps a great deal. I have to add that I admire both your and Anthony's work. I let you know how I get on with my new found information. Keep the awe-inspiring pictures coming.

Bryan Gumm
C11, SV102EDT, ToUcam, mx5-16 and so on....