Condensation/moisture during shoot at beach

[levinest]

What about the mirror? Could this be condensation on the mirror just before getting reflected onto the sensor? It definitely looks like condensation, although there's one spot that the rock on the left if practically pointing directly upwards at that might actually be dust on the sensor. The rest definitely looks like condensation, but where is the real question. Front of lens, back of lens, or mirror? If you've checked the first two already and are sure it's not on either of those, and it sounds like you've already done so, go for the third. Does your camera support putting into a mirror-up state so you can get a good gander at the mirror?

 

[Derrel]

Dude, I've thought about this and thought about this, and the ONE thing that makes perfect sense to me is this: you're using two ND filters, which are very difficult to SEE through, especially when stacked. ONE of them is loose in its frame which lets AIR IN. Just like a double-paned window that has a bum seal at one edge, AIR gets inside, and the water in the humid air condenses on one of the inner filter surfaces....

After 45 minutes, any water that has seeped in carried by the air will precipitate out of the air, and will have become attached to the inner surface inside your double-paned, air-leaking' ND filter sandwich...and it is in focus because the lens is stopped down to f/25. The water comes in and condenses...then later, like back at the hotel room, it might become airborne again, if the temperature inside the double-paned chamber gets higher...and also when you're back at the hotel wiping off the front filter there *IS NO WATER* on it because the water that we SEE in the pictures was actually INSIDE the leaky ND filter sandwich you'd adorned the lens with. This seems likely to me!

As you know, when the filter is far in front of the lens (as on some old deep-set lenses like the 55mm/3.5 Nikkor, where the filter is almost 1 and 3/4 inches in FRONT OF the front element, ANYTHING on the filter of that kind of a lens will show up. F/25 will cause the filter's surface to come closer to the plane of focus than say, f/2.8.

I see this same annoying water droplet behavior on one of my double-paned bedroom windows...the doggone seal on it was clawed through by a cat we had...he loved to claw at window seals, the little SOB...now "his window" gets these small water droplets inside of it whenever the humidity is "just so"...

Does this make as much sense to you as it does to me?

[Was there a clawing cat involved in this photoshoot--in any manner? Was there any 151 proof Ron Rico or Baccardi rum, or Everclear 19o proof grain alcohol "lens cleaner" involved?? ]

 

[KmH]

What about the mirror? Could this be condensation on the mirror just before getting reflected onto the sensor?

The mirror reflects up into the viewfinder and the secondary mirror, behind the main mirror, reflects down to the auto focus system. So, the mirror is out of the light path, up against the bottom of the viewfinder focusing screen when the shutter opens letting light from the lens get to the image sensor. So, there is no way condensation/dust or anything else on the mirror can show up in a photo.