Quote:
Originally Posted by cventer
Thanks everyone. Looks like alignment to scope is not the issue. Guess I need to track down what else this might be.
can someone also help with this questions. I am having a brain fart day and cant seem to solve th emost basic of maths problems.
My guidescope scale is 3.57 arc sec per pixel
My Scope and Camera is 2.8 arc sec pr pixel
If guide scope moves 1 pixel or 1/2 a pixel what movement in pixels or arc sec is this on my main imagers ccd chip ?
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Chris,
1/2 guider pixel = 3.57/2/2.8 = 0.64 imager pixel
similarly 1 guider pixel = 1.28 imager pixel
PHD can guide at an effective value of around 0.1 pixel if the guide star covers more than 1 pixel, so a slightly defocused star normally works better.
It uses the light falling on the adjacent pixels to calculate the centroid. If all the light is on one pixel it can tell where on the pixel it falls, so can't do anything until it starts appearing in an adjacent pixel.
I wish the weekend weather would improve so I can practice what I preach.