On the recent canoe image:
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Notice the area just left of center? My guess is a smudge on the lens is causing the loss of contrast in that one area. Could be a partial finger print, a drop of sweat ... it doesn't look like a spider web 'cause it doesn't go edge to edge. Some other shots had the same symptom.

The shaft of light looks sort'of like a shaft of light but I see nothing that could cause it so I'll guess flare. Also, that area left of center looks sharper, more circular. It's shot into the light so probably a smaller aperture so it would make sense that the smudge were sharper. It looks real enough but the atmospheric quality caused by fog in the air, on the lens or whatever - mix to add a lot of drama to yesterday's morning scene.