jjw004,
'One photon does not an image make...`
The only 'size` that has much meaning in
relation to a photon is it's wave-length.
It might help you to consider a photon as
as energetic event, frozen in time, fleeing
through the universe at 'C`,
seeking an opportunity to undo the itself,
(the event).
Felt poetic today, but the above is surprisingly
accurate come to think of it.
Pragmatist