As I understand it, the primary limitation on light output from an
LED is the temperature of the LED in operation. At output levels
exceeding 3 watts, at the present technology, the internal
soldered/brazed junctions melt and the LED fails. Due to the
brief time a "flash" LED is illuminated, such is in a cell phone
camera, heating isn't that much of a problem and higher output
levels can be attained.
This is true. The semiconductor junction gets extremely hot and needs an
elaborate heat sink, but there's only so much area of the junction that
you can attach the heat sink to, so there's a limit to how much heat you
I like just a little light. Some of my pet peeves are: People who need
four Coleman lanterns (or one even) at a campsite. People who have those
terribly bright dim headlights. People who have those terribly bright dim
headlights who then find it necessary to drive with their "fog" lights on
where there is clear skies and 50 mile visibility, making them look like
they have their lights on bright, not dim.
If a person uses a small amount of light, it is amazing what they can see.
When camping, I carry one of the one bulb LEDs with the button battery in my
pocket. I have seen them for free at conventions, and get all I can.
Everyone I give one to asks me if I can get any more, as they lost theirs or
broke it, or people ask them for one. But some are afraid of the dark, or
for whatever reason need to light up the area until everything is WHITE! It
is amazing what one can see in only moonlight IF they keep the f'ing lights
off long enough for their eyes to adjust.
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It's amazing how much light is lost to cataracts. As I aged, I
noticed that reading in restaurants became difficult and even when
driving, it never seemed to be bright enough. Remember, also,
that your dept of field decreases with the pupil increasing in
size. Even with new lens implants, I still don't see as well in
low light conditions as I did when younger.
As for the Harbor Freight-type flashlights, I love them. They
weigh little and are perfect for trips to the backyard to check up
on the smoker.
Do you have blue, gray or green eyes? I have blue eyes. My brother
has brown eyes. My late mother had brown eyes.
My mother would often turn on the light over the sink when I was
washing dishes and say, "Isn't that better?" I would reply, "No,
it's just brighter. It's not better." My brother always seems to
want rooms more brightly lit than I want them.
I don't understand why they make gourmet cat foods. I have
known many cats in my life and none of them were gourmets.
They were all gourmands!
I'm very nearsighted and the more light, the better for me. This is
because like a camera, when the iris is closed to a smaller size,
the depth of field (area in focus) is greater. I have lights all
over the place and I usually carry one or more flashlights with me
wherever I go.
Sorry, I'm an expert on myopia going on 60 years. I wear concave not
convex lenses. My lenses move the point of focus back so the light
will focus on my retinas. I'm -9 in one eye and -6.5 in the other.
I am nearsighted. Presbyopia started bothering me around age 50 and
I often take my glasses off in order to see very close up.
Have you looked into LASIK or even implantable lenses? I was
around -8 in both eyes and wore glasses since 2nd grade. At 51, I
had LASIK done. I laid on the table and in 5 minutes was told to
sit up. There was no pain or sensation at all. The next morning,
I was 20-25 in both eyes and that improved to 20-15 within a
month. It was almost like a miracle.
Later, cataracts came along and it was back under the knife, so to
speak. Again, the morning after the surgery, the implanted lenses
had taken me back to 20-25 and again by the end of a month, I was
20-20 and could read menus in dim light again.
Lasik certainly isn't for everyone. I can see distances fine (don't
understand where the astigmatism came from recently, though), but need glasses
(bifocals) for close work. Basically, Lasik would trade my distance vision
for short distances. Not a good trade.
BTW, I didn't start wearing cheaters until I was almost 55 and within six
months I had bifocals. That was three years ago.
Only -9? I'm -11.75 in one eye and not much better in the other. I've
been wearing hard contacts for 40+ years -- during which time I've lost
three. And for the past few years I've needed reading and computer
glasses (two different pairs) as well. "Fortunately" (??) I may need
cataract surgery within the next few years, so they'll be able to fix
the distance vision and maybe even (with "adaptive" or "multi-focal"
lenses) the presbyopia as well.
I got my first contacts when I was in college 40 years ago and of course
they where the hard plastic. I loved it when I got soft contacts and the
level of comfort was so much better but I haven't worn contacts for
years because I can't wear them when I'm working due to all the crap
that can get into my eyes.
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