Pixel Size for Guide Camera

[John Gill]

Is a small or large pixel size camera better for guiding?

Guidescope is a QHY mini guide scope. The main scopes are an APM 107/700 and a Celestron 8" EdgeHD.

Thanks

John

[mj.w...@gmail.com]

IMO the mini guide scope is not suitable for guiding a 2000mm focal length Edge HD.

I suggest you Off Axis Guide with a large pixel mono guidecam,  eg 5um, Binned X2 for sensitivity and image scale.

For the 700mm focal length APM with the mini guide scope,  the 5um pixel camera  will give an image scale of 7.93 arcsec/pixel, which the PHD2 guys will probably say is too much.

A 2.4um or 3.75um camera would be better.

Or even better would be a proper 240mm focal length guidescope with the 5um camera.

Michael

Wiltshire UK

[Bruce Waddington]

What matters is the image guiding scale which is a property that depends on both the focal length and the pixel size.  The preferred range is roughly between 0.5 arc-sec/px and 4 arc-sec/px but you can go a bit higher than that if you're not imaging at a fine image scale.  Small finder-scopes coupled with cameras having tiny pixels are usually a recipe for many headaches.

Regards,

Bruce