scale the sprite with 1.0/camzoomvalue... that keeps it same size regardless of camerazoom.
Or if you are allready scaling the sprite just multiply the scalefactor with 1.0/camzoomvalue...
example:
scalesprite sprite,xscale * (1.0/yourcamzoom),yscale * (1.0/yourcamzoom)
Or if you are allready scaling the sprite just multiply the scalefactor with 1.0/camzoomvalue...
example:
scalesprite sprite,xscale * (1.0/yourcamzoom),yscale * (1.0/yourcamzoom)