The given lens will focus the image at a fixed distance from the mount, corresponding to the location of the sensor plane for the standard specification for the mount style. That focused image is circular (unless cropped rectangular by baffles in the lens) and of fixed diameter (given a prime lens). The intensity of the light focused at the sensor plane should be consistently proportional to the intensity of light from the subject (no vignetting, for example). The intensity of the light on the sensor will be governed by the aperture. The size of the sensor can be smaller than the focused image, in which case it will only record a fraction of the field of view for the lens. The design-basis sensor will exploit the entire field of view (usually slightly cropped to avoid diffraction and other imperfections at the periphery of the field of view). Using a smaller sensor has no effect on the intensity of light on the sensor, so no effect on exposure. It has the effect of multiplying the apparent focal length of the lens by the "crop factor" because the smaller sensor "sees" only a fraction of the angle of view a larger sensor can capture. The net effect is that you can use a FF lens with any sensor smaller than FF (with spacer adapters to get the focal plane to align with the sensor), but if you use a lens designed for a smaller sensor/mount on a FF body you will have to introduce more optics to focus the image on the sensor and to spread the image to fully cover the sensor (or live with a circular image smaller than your sensor). If you use further optics to spread the image over a larger sensor, the intensity will be reduced and the lens aperture apparently smaller. To simplify the whole thing, just figure that the lens is going to do the same thing on a smaller sensor camera as it does on it's native FF camera, but the smaller sensor is only going to capture a cropped fraction of it, just as though you had taken an image from the native camera and cropped it.

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By sailors, I mean dinghy racers and sailboarders.

I'm old enough to remember when sailors called them "body bags".

I'd guess he's wearing a layer of windproof clothes over his drysuit for more warmth and to get a longer life out of the drysuit.

The brolly is part of the factory race kit, along with a thermos flask and a bilge pump.

Just wondering...

The virus is utterly apolitical. Humans with political biases that make them unwilling to accept facts of Nature are the greatest impediment to coping with the virus.

Nice photos, BTW!

Rich
In any fluid flow (air over water in this case), the friction at the boundary between the two causes the air to slow down and the water to get dragged along by the air (relatively slowly, but it can keep building to a storm surge). The further away from the water surface (up) the less the air is slowed, so the wind just tens of feet up is faster than the wind right at the water. "Boundary " in fluid mechanics refers to any interface between a fluid or gas, fluid and solid or gas and solid (the ground, pipe or canal walls, wings or foils, etc), or even between two streams of gas or fluid (look up Kelvin-Helmholz clouds). You are correct that the smaller area of the wing is also a factor

Kites will always be faster simply because the wind speed increases with distance from a boundary. These wings are nice, though, because there isn't a lot of string to deal with, tangle, or snag on someone's mast.

That's the best part. Stay home.

Unfortunately, the human body is pretty much opaque, even to UV. Of course, enough UV will eventually get through, but it will take awhile to burn through the char.

Pictures of leaves, bark and the whole tree, all with something of a standard size for scale (dollar bill, business card, not a pocketknife) would help.

I've been using four Sandisk 256MB thumb drives and a multi-function card reader plugged into either my laptop or my tablet to save backups of my SD cards . Compact and reliable, but hard to label.