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From: (no name) (no email)
Date: Tue May 01 2007 - 13:11:13 EDT
In a message dated 5/1/07 12:01:03 AM, Phil writes:
> I had planned to buy a Gen III night scope prior to leaving the
> Hawaiian Islands next Spring. My research came across a new product
> called SuperVision which claims to be superior to Gen III scopes and
> sells for less money. It seems to be based on a CCD chip which is
> basically camcorder technology. Take a look at the web site and see
> what you think. Pay particular attention to the comparisons between
> the SuperVision and the PVS14 night scope at the upper left of the
> home page. Looking at the differences and the price, this product
> looks almost too good to be true. What do others think?
>
> http://xenonics.com/default.asp
>
>
Phil,
It looks (from the web site) that Xenonics is using a side effect of CCD
technology that often plagues video and digital cameras to provide a form of
night
vision.
Most CCD detectors have a high sensitivity to infrared radiation. Sony once
advertised a "night shot" capability in its consumer camcorders. This simply
meant removing an IR blocking filter from the light path so that the camera
could form an image using the residual infrared light. Leica's new $5000 M8
digital camera has been criticized for not incorporating such a filter. As a
result
some black materials photograph as magenta. An add on filter costs $150 for
each lens.
Xenonics main product line is high powered xenon flashlights and spotlights.
The website states that by placing an IR filter over the lens, a long range IR
beam, invisible to normal eyes, can be projected. Apparently the night vision
scope uses an IR enhanced sensor and, possibly an IR illumination beam. The
high resolution images shown in the website are similar to the images captured
by the Sony "dark shot" capable cameras.
True image intensifiers use ambient light and amplify the number of electrons
jarred from a photosensitive cathode by each impinging photon of light
energy. These hit a phosphorescent surface and create a visible (green) image.
Gen I
light intensifiers released 100 to 1000 electrons for each photon, Gen II
more than 1000 electrons, and Gen III over 10,000 electrons. Magnetic lenses
formed the image on the sensitive surface. The advanced technology for the
higher
generations didn't come cheap but Gen I light amplifying scopes are on the
market for $200. These work adequately in normal starlight if you are content
with a fuzzy image. Auxiliary IR illuminators can be used to enhance the
image.
My Gen I night vision scope works for a long time on a pair of AA batteries. I
can't read a newspaper in the dark but it is adequate for finding a mooring in
a crowded anchorage on a moonless night. None of the above is a substitute
for radar.
Larry Z
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