So (without limitations of the viewfinder for example) looking through the viewfinder creates a brighter image than normal view would be. The lens would then work like a funnel(collects light from ...
Solid explanation behind the physics of the relation between aperture size and depth of field [duplicate]
Possible Duplicate: Technically, why is the out of focus area blurred more when using a bigger aperture? Many of us know that there is a relationship between the aperture size (f-stop) and ...
Possible Duplicates: What exactly determines depth of field? Technically, why is the out of focus area blurred more when using a bigger aperture? It is obvious that the aperture affects ...