pixel scale, over and under sampling

 pixel scale:

under sampling, image appears jagged or blocky

2.393 arcsec / pixel: original photo here

over sampling

0.131 arcsec / pixel: original photo here

 

The original photo is downsized to 12.5% for easier comparison. Stars are supposed to be bloated, but this is not obvious.

same image, without downsizing but cropped:

 The stars surely are spiky, but are they bloated or not?

As nowadays, stacking or lucky imaging(low arcsec per pixel), together with powerful post-processing techniques, over-sampling seems to be less of an issue

IMHO, good focus and tracking, long cumulative exposures, high signal to noise ratio, good post processing is more important

for 0.3 arsec / pixel scale, usually it is use with large aperture (> 1m) telescope in observatory

skyandtelescope

telescopes available to UK astronomers