Correct name for "pinhole lens" used in covert cameras?

Can I ask you specialists some questions about digital cameras.

I want some info on the optical quality of the lenses used in small
digital camera units lie this: http://tr.im/onwK.

Many sites call that a "pinhole lens" but when I search for
"pinhole lens" I get hits for lenses created by making a pinhole in
a card.

Is this tiny glass or plastic lens more correctly called by some
other term which I can use for a search?

Thank you.
AJ

PS---I would appreciate any links to info on the typical optical
quality and specification of these lenses. (Usual angle of view,
typical low light sensitivity, depth of focus, etc.) I can guess
these are probably low spec but how low?

In article , John Navas
wrote:

When you use URL redirection without preview you'll lose much of your
audience, since that's how spammers and scammers work. Instead:
http://preview.tinyurl.com/kshygw

or just use the original url. if it's properly delimited with angle
brackets, it can span multiple lines and remain clickable.

Alison J wrote:
Can I ask you specialists some questions about digital cameras.

I want some info on the optical quality of the lenses used in small
digital camera units lie this: http://tr.im/onwK.

Many sites call that a "pinhole lens" but when I search for
"pinhole lens" I get hits for lenses created by making a pinhole in
a card.

Is this tiny glass or plastic lens more correctly called by some
other term which I can use for a search?

Thank you.
AJ

PS---I would appreciate any links to info on the typical optical
quality and specification of these lenses. (Usual angle of view,
typical low light sensitivity, depth of focus, etc.) I can guess
these are probably low spec but how low?

The camera is known as : "Camera Obscura" Not sure it that's spelt
correctly but it sound right.

Alison J wrote:
Can I ask you specialists some questions about digital cameras.

I want some info on the optical quality of the lenses used in small
digital camera units lie this: http://tr.im/onwK.

Many sites call that a "pinhole lens" but when I search for
"pinhole lens" I get hits for lenses created by making a pinhole in
a card.

That's called "'pinhole lens" because the hole the video camera needs
for it's lens to poke through is very small, it looks a bit like a
pinhole and can sometimes be concealed behind a pop-rivet or what looks
like a hole left by a missing srew.

Is this tiny glass or plastic lens more correctly called by some
other term which I can use for a search?

The lens could perhaps be better described as an "afocal lens", because
everyting appears to be in focus (or at least equally blurred) and thus
does not need to be focused during installation.

Thank you.
AJ

PS---I would appreciate any links to info on the typical optical
quality and specification of these lenses. (Usual angle of view,
typical low light sensitivity, depth of focus, etc.) I can guess
these are probably low spec but how low?

On Sun, 14 Jun 2009 12:38:48 +1000, dj_nme wrote:

Alison J wrote:
Can I ask you specialists some questions about digital cameras.

I want some info on the optical quality of the lenses used in small
digital camera units lie this: http://tr.im/onwK.

Many sites call that a "pinhole lens" but when I search for
"pinhole lens" I get hits for lenses created by making a pinhole in
a card.

That's called "'pinhole lens" because the hole the video camera needs
for it's lens to poke through is very small, it looks a bit like a
pinhole and can sometimes be concealed behind a pop-rivet or what looks
like a hole left by a missing srew.

Is this tiny glass or plastic lens more correctly called by some
other term which I can use for a search?

The lens could perhaps be better described as an "afocal lens", because
everyting appears to be in focus (or at least equally blurred) and thus
does not need to be focused during installation.


Yet the more mechanically inclined user will take that small video-camera
apart or find the small focusing-helix collar and refocus that lens to
ensure pixel-edge-sharp details--maximizing their potential. It's the first
thing I do before I ever install or make use of one. (First use an x-acto
blade to carefully scratch/chip-away the small clear-green daub of
Loctite®.) My wide-angle IR nighttime wildlife surveillance video-cam at
home does just fine (now) at being able to discern the difference between a
raccoon or fox at 200 ft. in the pitch-dark. (A pair of plain old 100-watt
incandescent yard-floods when covered with IR filters put out massive
amounts of IR-only, even when not turned up full on their light-dimmer.)

The same optical quality is true for the miniature lenses in any
inexpensive laser-pointer collimation-lens assembly. The manufacturer's
costs often saved in alignment and focusing time spent because this is
generally a manual labor issue; dependent on the perception, patience, and
dexterity of humans. I'm more than happy to take one apart to pick up where
they left off. Taking a 5mW $10 green laser-pointer's optics and finely
tuning it to 1.05 mRads divergence. As long as I'm in there fiddling with
things I will also ramp-up the output to ~75mW. (They only set them for
low-output so as to legally sell them to the U.S.A., getting them through
customs.)15 minutes of my time brings me a $130-$250 laser for $10.

That aside, some of these small pinhole digital-cameras work great for
turning an optical microscope into a digital-microscope for just pennies,
compared to a digital microscope-ocular that might be sold at outrageous
cost by the microscope manufacturer themselves. Just because they are small
doesn't mean they aren't of high quality. Many a microscope owner would
regard the idea that "small can only be trash-optics and blurry" as instant
nonsense. Lenses of this nature are generally mass produced by only a
handful of companies; supplying to a wide range of industrial, research,
and home-use applications. High-quality microscopy being one of them. Sell
a single lens element at $70 to a research lab or microscope company
because they expect that price and are willing to pay it, then sell an
identical one to a "pin-hole" camera or laser-pointer mfg. for $0.20 each
because they expect that price too and will pay no more than that for a
mass-quantity order. They're not going to re-design their whole
manufacturing line just to ensure that they produce one larger order of
inferior lenses. Anton van Leeuwenhoek would also disagree with you, when
he was able to obtain sharp magnifications up to 500x by the use of only
one of these miniature lenses, hand-ground. This also happening over 350
years ago. Much has changed and improved since then.

Segue to r.p.d.: It is far, far, by far, easier to get a perfect figure on
a smaller lens than any larger one. The same holds true for all camera
lenses. This is precisely why larger diameter camera lenses will invariably
perform their worst at widest apertures. It is impossible for them to
figure glass that large to the proper curvatures, at any
consumer-acceptable costs that is. With smaller camera lenses this is
wholly possible, easily accomplished minute-by-minute, camera-by-camera.

On Sun, 14 Jun 2009 20:56:58 +1000, Bob Larter
wrote:

The Correction Police wrote:
they left off. Taking a 5mW $10 green laser-pointer's optics and finely
tuning it to 1.05 mRads divergence. As long as I'm in there fiddling with
things I will also ramp-up the output to ~75mW.

HAHAHAHAHAHAHAAHAHAHAhahahahahahaha!

Oh ye of such vast ignorance, with an attention-deficit deeper than the
Mariana Trench. Google for laser pot mod Some people adjust their's
higher, to 150mW output, but I feel that that will shorten their life
greatly. I do have one set that high, just for the life-expectancy
experiment. It readily ignites a phosphorous match in under a second. It's
still working two months later, but for how long. Granted it is only used
intermittently.

The ones I buy direct from China are actually $8 each, shipping incl., (not
$10, but some people can't get them that inexpensive), all easily adjusted
for a 75mW output. Their heat-sink is more than adequate to be tuned that
high. The emergent beam of light clearly visible in a sunlit room after the
exceptionally simple modification.

Every time I am engaged in a group astronomy discussion (which invariably
happens a dozen times a year while photo-trekking or at home) I like to
hand a laser to each so that they may easily point out objects they are
curious about. It's much less time-consuming than playing, "Where? There?"
"No, over there, see where I'm pointing my finger?" "Wait, let me line up
my eye with your arm..." This is also a good time to educate any young
children that might be present on the dangers of lasers this powerful. They
too get to use them to ask about things in the sky. It's a wonderful
opportunity for them to display and learn adult-level responsibility. A
multi-faceted lesson. I teach the adults an important lesson too. All
adults in attendance are more than willing to keep explaining safety issues
to their children, they are motivated by fear of being permanently blinded
by their own child. It's "grow up" time for all. With fun astronomy info
thrown in for good measure.

(Imagine a world were every person was given an atomic weapon when born,
you useless sub-human idiots would all grow up immediately.)

Educate yourself before you make a fool of yourself, yet again. It's
getting tiring watching you do it so relentlessly, so predictably.

There's nothing sadder in the world than someone who chooses to remain as
ignorant as you. Something tells me that you'd be the one out of
one-hundred-thousand that I would hesitate to hand a 75mW laser to. You
appear to be the type that could never learn, no matter your age. The kind
of life-form where your genetics should be prevented from continuing.

In article , John Navas
wrote:

When you use URL redirection without preview you'll lose much of your
audience, since that's how spammers and scammers work. Instead:
http://preview.tinyurl.com/kshygw

or just use the original url. if it's properly delimited with angle
brackets, it can span multiple lines and remain clickable.

Not necessarily -- it will still be broken in many news clients.

then the news client is broken. this is 2009, it's time to update.

plus those services don't necessarily maintain the url reference
forever and if someone finds the post on google groups some time in the
future, the link will be dead and they'll have no way to load the page.

In article , John Navas
wrote:

or just use the original url. if it's properly delimited with angle
brackets, it can span multiple lines and remain clickable.

Not necessarily -- it will still be broken in many news clients.

then the news client is broken. ...

[shrug]

I deal with the world as it is, not what I'd like it to me,
but as always, YMMV.

translated: i'm stuck using primitive software and refuse to upgrade.
ymmv.

On Sun, 14 Jun 2009 14:10:35 -0400, nospam wrote:

In article , John Navas
wrote:

or just use the original url. if it's properly delimited with angle
brackets, it can span multiple lines and remain clickable.

Not necessarily -- it will still be broken in many news clients.

then the news client is broken. ...

[shrug]

I deal with the world as it is, not what I'd like it to me,
but as always, YMMV.

translated: i'm stuck using primitive software and refuse to upgrade.
ymmv.

Translation, nobody is stupid enough to follow any of your lame troll's
advice.

Alison J wrote:
Can I ask you specialists some questions about digital cameras.

I want some info on the optical quality of the lenses used in small
digital camera units lie this: http://tr.im/onwK.

http://www.google.com/products?hl=en&q=spy+camera+lens
It's inherently going to be a very small low resolution camera requiring
bright light to form an image through a tiny hole. Tiny hole means tiny
amount of light. Even if you could focus such a lens on the sensor of a
high performance camera, diffraction would limit resolution severely.
Tru pinhole photography requires very long exposures due to the tiny
amount of light passing.

This one for example:
http://www.spyville.com/3213ccdbwcam.html
$69.99
1/3" CCD Image Sensor (4.8mm x 3.6mm, the very smallest)
512 x 492 pixels
Min Illumination: 0.1 Lux
Lens Pin Hole: 5.5mm, f/3.5
Size: 32mm x 32mm

Probably a clear glass/plastic cover, an open pinhole would let dust in.
The diagonal of that sensor is 6mm so the 5.5mm lens is a normal lens,
with a field of view comparable to a 50mm lens on a 35mm format camera.
The aperture of f/3.5 means 5.5/3.5 = 1.6mm diameter opening. That's
probably too big for an actual pinhole so perhaps there is an actual
lens in there. If so, it's probably nothing fancy because diffraction
will wipe out most of the detail anyways. It wouldn't be worth putting a
better sensor in there either.

I have a pancake lens for 35mm format, the opening is 16mm dia. which is
45mm f/2.8 capable of very high resolution images in low light.



Many sites call that a "pinhole lens" but when I search for
"pinhole lens" I get hits for lenses created by making a pinhole in
a card.

Is this tiny glass or plastic lens more correctly called by some
other term which I can use for a search?

Thank you.
AJ

PS---I would appreciate any links to info on the typical optical
quality and specification of these lenses. (Usual angle of view,
typical low light sensitivity, depth of focus, etc.) I can guess
these are probably low spec but how low?


--
Paul Furman
www.edgehill.net
www.baynatives.com

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