The Paterson Micro Focus Finder is designed to produce a highly magnified image of the picture that is being projected onto the enlarger baseboard. This allows the grain structure of the negative to be brought into sharp focus as the image is adjusted prior to exposure of the printing paper.
The eyepiece is adjustable for individual eyesight. This adjustment is made by carefully moving the eyepiece up and down while looking through it, until the cross hair built in to the finder is seen to be sharp. The eyepiece is then locked into position using the locking screw provided. A sliding shutter protects the internal mirror when the finder is not in use.