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| The depth of focus
of a lens |
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The depth of focus of a lens varies with the
focal length of the lens, the aperture (the size of the opening of an iris
or diaphragm) of the iris and the working distance (distance
between lens front and object). The depth of focus further depends on
the illumination of the object to be shot. The higher the
illumination (measured in lux) by the dental light, the smaller
the aperture of the iris (and electronic iris !) can be and the
wider the dephth of focus will be.
The lens of the ThirdEye dental camera has a
fixed iris (besides the electronic iris built in the ccd chip)
with a diameter (aperture) of 2,2 mm. This aperture ensures
sufficient light falling onto the ccd chip with all
dental lights on the market even those with less lighting
intensitiy. |
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| Focussing the lens |
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We all prefer a certain working-distance -
distance of the front of the dental light to the mouth of the
patient - of our dental-light.
With a good illumination the camera
must
be focused to the tooth or working area we are treating only once. Slight
changes of the position of the dental light do not need new
focussing but are compensated by the wide depth of field of the
system and the image remains sharp.
However, if the alteration of the distance is
big - more than 10 to 20 cm - you have to focus again. To focus
just turn the outer tubus of the lens.
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Why no
autofocus ?
You wonder, why there is no autofocus integrated in the ThirdEye
dental camera ?
There is a simple reason for that. It wouldnīt work ! An
autofocus normally adjusts the focus to the middle of the shot,
in our case our working area. Now, if we were not working in the
patientsī mouth all would be fine. The autofocus would focus to
the tooth you want to show to the patient. But, as soon as the
patient would move his head or we would be working with our
dental mirror or fingers in front of that tooth surface the
autofocus would nervously focus back and forth, the image never
would be sharp at all.You wonīt be able to video tape a whole
treatment with an built-in and activated autofocus !
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| Adjusting
manual white balance (important) |
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The ThirdEye dental camera
can be operated in automatic or manual white balance modi.
The preferred modus should be
the manual white balance, because in this modus only you
will have optimal color reproduction under any lighting
conditions.
To adjust the manual white
balance direct your dental light with th ecamera onto a
white sheet of paper in front of your patients mouth or in
front of the head rest of the dental unit. Now push the red
button on top
of the camera towards the housing (short button). Finished.
Check the colors of the gingiva
of your patient or the colors of your skin skin on the monitor |
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| Lens hood |
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The outer tube of the
lens is the only part of the camera touched by the dentistīs
hands. To prevent a contamination of the lense, we deliver a
special lense-protection. This lens hood is made out of
polypropylene. This material can be disinfected in the
disinfection bath or even be autoclaved. The lens hood
simultaneously serves as sun shade and ray shade. It prevents
other light sources - e.g. your light on the ceiling, day light
falling through a window - falling onto the front lens, thus
reducing contrast of the system. The lens hood allows focussing. |
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| Shots with the
dental mirror |
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If
you want to shoot areas or tooth surfaces only visible with
your mirror, the light of your dental light should come out of the
direction
of your head. The central beam of the dental light
then will be parallel to your visial axis. What you see in your
dental mirror will be what you get on the monitor screen*.
(*
provided your dental assistant controls
the focus - if necessary) |
| This userīs manual
is available as Word-file
or PDF-file |
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| start of page |
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