Hi, new(ish) here. Have recently bought an Imac 27". I make hundreds of fishing videos and have been learning how to edit with iMovie. I use a Gopro Hero 3 Black Edition. I have noticed that the original footage is crisp and clear HD, however as soon as i import a clip there is a visible loss of picture quality. With every effect added the quality deteriorates further, leaving some projects hard to even view. Any clues as to whats going on? Like i say...original clips and pictures when imported from the camera to the desktop are awesome quality and the Imac's 2560 X 1440 screen resolution displays and plays clips and pics fine....i'm thinking its either faulty software (iMovie) or i need to tweek import settings...... Any clues as to where i can start? Thanks in advance. I posted a similar question on the Apple support community forum, so far no replies, however, there are many similar questions posted with no or ineffective solutions offered.