Blurry vision underwater is due to pupil dilation, which can be controlled to see as if wearing mask

[Rred]

To some extent, BLUE water is also going to be problematic. Evolution has formed the human eye so it is more attuned to the color of threats and rewards. Nothing that's edible is really blue (blueberries not being a primary food source(G) and no predators are blue. Neither are fields or forests.
So it may come as no surprise that the human eye also has the most problems FOCUSING ON BLUE LIGHT regardless of the conditions. Which also has to do with the wavelength of blue light, being almost all the way at the wrong end (unimportant end) of the spectrum, for the design of our eyes.

Anyone who has ridden in the front of subway cars (blue lights are used to indicate emergency call boxes in the tunnels) can tell you the blue often becomes a blue/purple blur, and that the rage for blue LED indicators is just plain foolishness is you're trying to really see things.

We're just not designed to work optimally under water. In many subtle ways.

 

[lowviz]

The problem is that the title of the thread is misleading. It is not dilation that makes things blurry, it is things being out of focus. "Stopping down" the eye gives more depth of field.

Precisely.

I suggest that the OP look up "pinhole camera" while watching internet pranks...

 

[hammet]

The problem is that the title of the thread is misleading. It is not dilation that makes things blurry, it is things being out of focus. "Stopping down" the eye gives more depth of field.

This. But that won't help you see any less blurry under water when looking at a particular object. It's basic optics. I doubt the veracity of this video. An underwater eye test with these subjects would be the only proof.

 

[Doc]

Any Opiate will constrict your pupils (fancy name is Miosis).

I prefer Hydrocodone but it's getting difficult to pass off these Xerox copies of my last scrip. Heroin will work.

(What in hell are we talking about here?)

It is so much darker underwater, with dramatically reduced contrast, it's amazing that we naked pink monkeys can even see an occasional Squirrel Fish. (We are "shutter priority" for all you recovering Silver Halide addicts).

Diminishing the quantity of light for increased acuity? Oky doke.

Ooh Ooh (the kid in the front row of the class wildly waving his hands) Ooh Ooh, I know! Bring a BMF flashlight!

 

[lowviz]

...//... (We are "shutter priority" for all you recovering Silver Halide addicts). ...

Oh well, my EX avocation. Miss it.

Google 'Zone 6' and see how far you have to go to get something relevant...

Spoiler

Understanding & Using Ansel Adam's Zone System

 

[TMHeimer]

So if we learn this pupil thing we never need a mask again for refraction? You'd think they would've thought of that long ago.

 

[lowviz]

Merry Christmas, or whatever your preference. I'm cool with most anything. (Kodachrome 35 was too radical for me.)

Rock on!

Oh yeah, the thread...

(I worked for the big X as a student and spent my weekends with Uncle Yellow. Just a long run around Irondequoit bay.)

 

[Doc]

25 was the ASA, 35 was the size. Not for pussies or dark things. Kind of like film on acid.

And another thing……

 

[lowviz]

Yes, more than I could handle in an apartment. I was true to B/W until it became too difficult to pursue.

Digital and Photoshop killed the magic forever...

 

[wKkaY]

Wow I didn't know that pupil dilation can be voluntarily controlled. That would help my dark-adapted vision after I got my eyes lazed.