Half a croissant, on a plate, with a sign in front of it saying '50c'
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Transition Lens Predarkeners

I have already eaten half of my hat for breakfast. The rest is in my lunch box.
  [vote for,

There was an idea posted previously for instant darkening lenses, wherein I posited (speaking entirely out of my arse) that transition lenses darken pretty quickly. I didn't actually own a pair, and was basing my claim solely on a very misleading television advertisement. I wholeheartedly apologize for that.

I now do own a pair, and now know exactly what prompted the poster of that idea to get creative about finding a solution. Even in full, direct sunlight, it can take up to a full minute for these things to darken sufficiently to be considered, by any reasonable measure, sunglasses. Once inside, they take up to 10 minutes to go clear again. I don't have a solution to the indoor clearing delay, but I think I have one for the darkening delay issue.

My idea is for a hat with a UV lamp under the bill. It can be a narrow, low profile pair of bulbs with a simple switch. When you're about to go outside into the sunshine, turn on the UV lamps a minute or so before actually going outside to predarken them. A small solar cell on the top of the hat can serve as a safety kill switch to turn them off automatically once exposed to sunlight to save you forgetting and accidentally giving yourself a sunburn. A two minute timer switch might work as well.

21 Quest, Jun 03 2014

Turning 3D shutter glasses into automatic sunglasses http://hackaday.com...tomatic-sunglasses/
This looks like a fun experiment [xaviergisz, Jun 03 2014]

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MaxwellBuchanan, Jun 03 2014

       Unless you're on the water and racing from the dark hold to take the wheel before you run into a sailboat that came at you out of the glare, the darkening time is rarely critical. The do transition quickly enough that by the time you actually have to look at a glare you are fine.

       The reverse can, sometimes, be a problem, and I have learned to take my glasses off and shield them for a bit before entering certain locations (mostly historic ones where they get annoyed if you hold up the line and the floors tend to be uneven).
MechE, Jun 03 2014

       MechE, it can be problematic when driving out of a wooded area with lots of shade that has a curve just outside the exit.
21 Quest, Jun 03 2014

       My auto-darkening welding hood activates in 1/100,000 of a second or so (much faster than it takes the arc flair to go the distance between the visor and my eye). Since mine is a really really nice one, it has variable shade settings from 9 to 13 (sunglasses typically run from shades .75 to 1.5, but I've seen some as dark as 2.5) and it has a sensitivity adjustment that can be set high for low-light shop conditions but turned down for outdoor work to prevent it from being accidentally triggered by the sun.

       I've long wondered why this tech hasn't hit the sunglasses market yet. I've seen plenty of rich idiots who spent more on their shades than I did on my welding hood (about $300). It seems like a no-brainer.
Alterother, Jun 03 2014

       This idea came to me today again whilst driving, because transitions, being UV activated, don't darken in a car because the windshield has a UV filter. And yes, I do have a very nice (and expensive) pair of prescription sunglasses. I had left them in my other car by mistake when I set out for Wallace, ID and had to make the westward drive home into the setting sun. It sucked.
21 Quest, Jul 04 2022


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