A new exhibition at Perth Museum and Art Gallery is celebrating a photography technique which makes positives out of negatives – quite literally. Entitled Magnus Jackson Photographer, the exhibition, which is shown in lowlight to best show the images on display, features work by one of the local pioneers of wet plate collodion photography followers of the historic technique. Dating back to the Victorian era, the collodion process, which has undergone a recent revival, is a technique which exposes individually hand-coated plates while still wet. Magnus Jackson (1831-91) was well known in Scotland as a landscape photographer with a particular interest in trees.