OK - back to S: I'll hit a few things for you to work with, but there's more. Best to have a really good instructor with you, but give these a whirl: Oh - disclaimer - this has nothing to do with pilot issues (NVGs, instrument panel lights, glare, etc) - it's about being on the ground in the dark. Some of it is very relevant to being on the water after dark and some of it is true but irrelevent out on the water.

1. You cannot see anything directly in front of your field of vision. Forget it; you're totally blind there in S mode. If you're a ground-watcher when walking in the daytime, you're going to fall down a LOT walking around with S vision. Quit looking at the ground all the time.

2. You MUST look at things off-center - use the top, side, bottom of your field of vision. Around 20 degrees or a little less works best for most folks.

3. A tiny bit of light goes a long way with S - unlike cones, there are LOTS of rods feeding each optic nerve synapse - some say as many as 100 rods/nerve ending. That's a lot of additive input.

4. S is GREAT at detecting motion - it totally beats the snot out of P for motion detection. Use that. Stop, Look, Listen, smell, feel - do all that. Use the stops especially for detecting motion while you're really LISTENING - amazing what useful info you gather that way. Turn your head this way and that while you're doing this - even a nearly imperceptible breeze sounds like a gale in your ears, and it sems to automatically put the eyes into hyper-motion detecting mode.

5. CONTRAST - use the sky, use the variation between ground and trail and so on.

6. This is tricky and hard to explain/learn; it's also contradictory but true: If you stare (using the edge of your vision) at something in S mode, it washes out fairly quickly (rhodopsin, or visual purple, bleaches out FAST because it's so light sensitive). So you lose something you're intently studying... that's how a stump becomes a big fat racoon ot boogey man or - anyway, KEEP LOOKING, but ever so slightly twitch your eyes so you slightly shift the exact place the image is falling on your retina. Keep this up for more than 30 seconds and it will make you gasp - you can see the darned thing rather well! The best explanation I have heard is that our brain retains each slightly different image and uses them to build an accurate composite image. Which brings us to

7. PRACTICE - you're darned tootin' that we need to train our brains to show us what our eyes see and our optic nerve pre-processes. We get far more sensory input than we can consciously deal with and it's further complicated in S mode vision because suddenly other senses positively LEAP into the forefront, clamoring to deliver THEIR information. Don't discard that cool river of perfume running out of the short grass prarie that you just passed through, but also train your brain to better process the optic information you're getting - it is VERY different than the optic input you get almost all the time. We're clearly diurnal, but we can handle nocturnal pretty well with practice.

There is also very compelling evidence that after being in S mode for a few hours, all of a sudden our brain (or optic nerve or both) REALLY kicks in with the image processing, and the more often you use S mode the faster that kicks in. Caution: The opposite is true if you are exhausted to the point of being snoozy, at least in my experience. That's when the monsters start appearing in the darkness... shouldn't be moving then anyway, unless you're on some military marathon-death-march maneuver.

Ummm - did I mention that you simply must give yourself time to dark adapt? There are lots of techniques to help keep that time from being unbearably long, but even in the best of circumstances it takes at least 30 minutes to get to about 3/4 throttle in S mode. That's 30 minutes of no-BS DARK. If you've really been screwing your eyes up for days with bright sunlight you may be out of luck for geting anywhere better than about 10% - 25% of your basic capability working on a given night - guard your vision during the day if you know you're going to be out at night. It varies from person to person, of course.

Diet shouldn't matter for properly fed folks, but if you're vitamin A deficient, you're toast. Eat your veggies regularly - dark green leafy stuff and beta-carotine things (carrots, yellow-orange squash, etc.). But go easy on it - don't want Vit A poisoning, so just take in the normal healthy dose naturally.

A bright red light can DAZZLE you - make your pupils contract - but that will NOT wash out dark adaptation. Pupils dialate back open very quickly compared to your dark adaptation time. Rods are hyper sensitive to a short wavelength in the "green" range (around 510 nm wavelength), so if you use anything more than the faintest glimmer of green light, you will knock out your dark adaptation. There's a fine line there that I'll leave to the astronomers, who may need to use a glimmer of green for instrumental or map reasons, but for us woodshounds, stay away from anything but red. Look at a red Photon directly and you'll be dazzled. Shield it with your hand and direct the light at whatever you need to see and it will have no adverse impact.

Ach! There's more, but this post is already too long. Go practice! Walking with S mode vision fired up and humming just so totally beats the stuffing out of that little cone of light from a flashlight (torch) - you can only see where the light shines, have about nada for peripheral vision, and once you get it, you'll really HATE running into flashlight walkers. S mode gives your brain a huge panorama of visual input that you're largely unaware of during P mode vision. You can see things way off the sides... like I said, practice.

Again, remember that the words "acuity" and "scotopic" do NOT belong in the same sentance - the world is a bit fuzzy in S mode; maybe something like 20/200. And that is a good reason to wear clear eye protection if you're trudging down an overgrown gloomy path in the woods - you may very well be able to see everything quite well for your purposes, but that tiny little twig... there are techniques to spot those but that's more than I care to take on at a keyboard - best done close beside a person, pointing out things like that.

Which brings up a point - if you wear eyeglasses, they will be of comparatively little help in S mode for most folks, but they WILL protect your eye from casual twigs. If your uncorrected vision is pretty bad, leave them on even out in the open, because they will help up to a point.

Have fun <img src="/images/graemlins/cool.gif" alt="" />

Tom