Thank you, John, Gareth & Franc.  [I work on the weekends & will have to be brief at the moment.]  I have much to muse over...  
John, the "aboutness" that you described as essential to Kantian-defined apperception relates to intention and self-awareness, right?  So, grammatically speaking, what distinguishes apperception from proprioception is the active voice, a directed (perhaps self-directed) cognitive act?  
I think that the term apperception begins to lose its meaning for me when I begin to apply it to a specific embodied act, such as the act of camera-using.  As a philosophical term, it makes sense to me, but when applied to an embodied experience (such an experience implies a simultaneity, continuity & unity...a continuous flow, so to speak), does it begin to lose its meaning or usefulness?  
Franc & Gareth, later (when I'm not rushing off to work) I'd like to address the sense of "suspension" while camera-using.  Perhaps it has something to do with the intentionality (the intense scrutiny of an object) occurring in the midst of the cognitive-perceptual flow described above...
Many thanks.
Andrew