biology coarse adjustment kn diaphragm education eyepiece fine adjustment knob instrument lens medical microscope object holder objective turret ocular lens optic optical research science viewing beautiful blue clear coast coastal heather hills horizon minch ocean peaceful remote rocks scenery sea shore shoreline sky water bay Catalan catalonia Catalunya cliff coastline conifers costa brava cove green headland mediterranean pines rock rocky seaside Spain trees view woodland boulder boulders granite gray grey island islands land landscape Maddalena natural nature pink rough rugged Sardinia distance distant isthmus spit