[Brightcolours]

Have been using 750D plus 100mm macro for scanning black and white negatives. But I never mastered metering. I usually select a slide, meter with living view, then keep exposure for the rest, however sometimes I am having surprises since what the camera sees(or myself) sees as shadows are actually highlights and vice versa, any tip for setting adequately exposure?

I can't yet make sense of your issue. If one negative goes ok, and you keep the settings the same, the camera can't suddenly get things terribly wrong with other negatives, unless the one you based the metering on was unusually dark or light? With uneven exposures/subjects you will always have to adjust the exposure times on the camera.

 

And it would be more correct to say you photograph them, instead of scan