The Perfect Picture’s Creatively Correct Exposure video tutorial is interesting to watch, but it encourages newbies to link two different facets, “technically correct exposure” and “creative choice of f/no for depth of field” without a seam. Sure, a veteran photographer juggles both these facets intuitively.
The newbie though, does need to pause and think that these are two facets – they overlap in the fact that the f/no is present in both facets but that’s the only thing they overlap in. Otherwise the spiral of confusion, that winds into equivalence of every facet (f/no, shutter speed, ISO, sensor size, focal length) perpetuates.
In truth, Bryan is demonstrating exposure (the permutations of shutter speed and f/no). He’s not speaking of twiddling the ISO dial (because in the film days, you could not easily change ISO in mid roll) nor is he talking about the effect of different digital sensor sizes and focal length.
Bryan Peterson explains this slightly better in this second video – emphasising choice of shutter speed:
and another video, emphasising f/no
In truth, Bryan's videos and the title of this very blog post should be more aptly changed to "Choosing an aperture and shutter speed permutation to effect creative control of the visual aspects of the photo" rather than "Understanding Creative Correct Exposure". Because we have not yet begun to discuss whether we should underexpose or overexpose a scene (in modern parlance on a digital camera, twiddling the Exposure Value compensation dial, to creatively darken or lighten the whole photo so that we can target the face of a person as the most important element in the photo.