From: Jeff Jones on
On Thu, 01 Apr 2010 00:53:39 -0400, "stephe_k(a)yahoo.com"
<stephe_k(a)yahoo.com> wrote:

>David J. Littleboy wrote:
>
>>
>>> Because the beam was dispersed.
>>
>> So build a unit that does the same dispersed-beam thing and reads out a
>> distance. Not a problem at all, if it were actually something enough people
>> wanted to make it a viable product.
>>
>
>Yeah, I'm sure the camera makers have no interest in a faster, more
>accurate focusing system that would work on a blank wall, in the dark
>etc. Obviously it must be a slight problem given there isn't anything
>like this being made.
>
>Stephanie

The laser diode projected pattern system in earlier Sony cameras like the
F707 and F717 can do all this, even the blank-wall scenario, and do it well
and fast. But they fell out of popularity due to peoples' paranoias about
laser sites on guns. Paranoid police were inclined to try to disarm the
laser-toting assailant. Though I've not heard of anyone who was focusing
with a Sony F7x7 in an urban environment at night actually being shot and
killed by police, the potential for this happening was there. Keep in mind
too that these models were released while the 911 panic was still high.
Rather than feed into peoples' "OMG, it's a TERRORIST!" fantasies and
paranoias, Sony dropped this more effective low-light and low-contrast
focusing assist system.

OT ramblings:

Of course, 3 generations now growing up with needing warning labels on
everything from bubble-gum to hair-brushes, 3 generations who can't even
think for themselves, people who have to let others always make their
decisions for them, lots of good ideas (like the laser focus-assist) have
gone into the crapper because of the imagined "danger". When I grew up we
learned to not touch the electric burner on the stove when it's not glowing
by touching it--one time. We now have 3 generations of paranoid idiots
making all the decisions for everyone else who are just as equally idiotic
and afraid of their own shadows, or just the potential for a dangerous
shadow being enough.

I was playing with my 1950's 2MeV electrostatic generator tonight, I
finally found some good belt material for it again. Can you imagine the
warning labels that would require for today's consumer? I would offer one
for the list, "When it is operating and you are explaining how it works to
others, do NOT accidentally point your finger at it from any closer than 30
inches." Did that once. You only have to do it once to learn. Others who
had this non-warning-label lesson have described it as, "Well ... it
doesn't quite reach your heart." Takes about 2 days for the feelings to
become normal in your arm. Out of all my fun (and potentially dangerous)
toys, friends have named this one "NOTaTOY" For parties they'll even say,
"Bring out NOTaTOY!" Had one drunk partyer want to do the hair-raising
experiment. I warned him many many times, "DO NOT remove or try to
reposition your hand while you are charging up." Did he listen? The first
small arc from moving his hand caused him to flinch further away, until
each arc made him flinch further and further until he was finally getting
zapped repeatedly with the full voltage. Which finally made him jump off of
the fiberglass crate he was standing on. So we all got to laugh while he
ran up and down through the whole house yelling "OW! OW! OW!....." Damn was
that funny.

I think all warning labels, guard-rails, and safety guards should be
removed from everything for the next 30 years. So the last three
generations become smarter, responsible for their own actions, and learn to
think for themselves again.

From: Savageduck on
On 2010-04-01 16:02:02 -0700, Paul Furman <paul-@-edgehill.net> said:

> Savageduck wrote:
>> On 2010-04-01 09:48:37 -0700, rfischer(a)sonic.net (Ray Fischer) said:
>> -------------------

>> Sounds like an urban legend. Got a cite?
>>
>> < http://en.wikipedia.org/wiki/Lasers_and_aviation_safety >
>
> Speaking of laser focusing systems:
> http://gizmodo.com/5464119/make-your-own-rig-for-ultra+high-speed-photography

Now there you go!


--
Regards,

Savageduck

From: Alan LeHun on
In article <4bb528d5$0$5591$afc38c87(a)news.optusnet.com.au>,
contact(a)this.ng says...
> Do you have a cite for that, Alan? I would seriously question the
> physiological damage an "AA" powered laser could do over such a range,
> through so many translucent barriers. Inverse-square law, and all that...
> Not to mention moving target, and beam dispersion..
>

The strongest lasers available without stringent restrictions are about
500mw. These have a nominal optical hazard distance (NOHD) rating of
around 150m.

Such lasers can still "blind" (iow are optically overwhelming) at
distances measured in 10's of miles, but as you say, you would need to
have a very good aim and a very steady hand.

I have not heard of any pilot suffering eye damage from accidental or
deliberate targeting by laser but with modern star-pointer lasers, aimed
at an aircraft during final approach, permanent eye damage is feasible.

I did once see a handheld laser for sale with a peak output of 900mw. It
was over $10,000 and not something that a kid would find in his stocking
on xmas day. Such lasers are powered usually by proprietary ni-cad but
sometimes by standard "D" sized batteries.

--
Alan LeHun
From: stephe_k on
Jeff Jones wrote:
> On Thu, 01 Apr 2010 00:53:39 -0400, "stephe_k(a)yahoo.com"
> <stephe_k(a)yahoo.com> wrote:
>
>> David J. Littleboy wrote:
>>
>>>> Because the beam was dispersed.
>>> So build a unit that does the same dispersed-beam thing and reads out a
>>> distance. Not a problem at all, if it were actually something enough people
>>> wanted to make it a viable product.
>>>
>> Yeah, I'm sure the camera makers have no interest in a faster, more
>> accurate focusing system that would work on a blank wall, in the dark
>> etc. Obviously it must be a slight problem given there isn't anything
>> like this being made.
>>
>> Stephanie
>
> The laser diode projected pattern system in earlier Sony cameras like the
> F707 and F717 can do all this, even the blank-wall scenario, and do it well
> and fast.

Again we aren't talking about a projected pattern, as other cameras do
this too, they just don't use a laser diode to project a pattern for the
phase or contrast based focus system to lock onto. What we were
discussing was a system like the laser distance measuring devices which
are probably more accurate and faster than the current systems.

David was claiming it would be no problem to make a laser focus system
with a dispersed beam, which I wonder how it could work for anything
other than shorter distances these projected beam focus aides work at.
And if it was such a simple problem to solve, why all of these laser
measuring devices don't use that sort of beam since it would be safer.

Stephanie
From: stephe_k on
Ray Fischer wrote:

> 3) You have the problem of blinding people with the laser beam in the eye


You use the same reason you called BS on someone else for using? LOL!

Stephanie