Hi, was trying to make a decision to buy a sony 12-24 lens for use with my Sony a7r5 body or the sigma 14-24.My goal is to do hand held landscapes with a shutter speed of around 1/8th.Is the Sigma lens stabilization working with the in camera sony stabilization as effective and using a sony lens with a sony body?Thanks

There should be no difference using the Sigma as opposed to the Sony.I find that with my A7RIII, I have no difficulty getting sharp hand-held shots at 1/8 second and 20mm.  If I am very careful to hold the camera steady, I can get down to 1/4 second, but that doesn't work every time.

Neither of these lenses has built in stabilization.  For focal lengths this wide the camera IBIS is more than enough.