Re: Guider exposure times?

Dean Jacobsen

My experience has been that guiding camera exposure times will vary according to how steady the sky is.  You want to have exposures long enough to average out the seeing so you aren’t chasing a false centroid calculation by the guiding software.  For me, I want to keep my guide exposures as short as possible because I dither the guide star every one or two exposures (for better pixel rejection during stacking, “walking noise” issues with my camera, and because I frequently use drizzle integration) so I want to minimize the settling time before the next exposers is started.

I generally use 3 sec for calm nights but will use 5 sec for nights with bad seeing.

It is very instructive to watch seeing scintillation at longer focal lengths with an eyepiece and see how a star will move around.  Then you can easily see how short guide exposures will give you an inaccurate result.  Also, try taking a 1 or 2 sec exposure with your guide camera.  If the star is misshapen or elongated then you might not be getting an accurate position calculation.
Dean Jacobsen 
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