Olympus 75mm Lens

I’m starting to work on getting the most out of the Olympus 75mm f/1.8 lens which is an effective fast 150mm focal length.  I have always liked the lens except that I wish it focused closer and was weather resistant.  My intention is to see if I can utilize that lens at an effective 150mm focal length when opened to wide apertures more often.  It is part of an effort of trying to decide if I want to utilize prime lenses more than zoom lenses with the 75mm being my longest prime lens.  Using it that way gives me a far more pleasing use of out of focus colors, in addition to B&W images with narrow DoF.