THE SHUTTER
Here you will find two preliminary designs for the shutter of the AUDINE
camera. In the near future, they will be described in more detail. Possibly,
a small production may be envisaged.
Thierry Maciaszek's prototype. An electromagnet
motorises this shutter. (This electromagnet is available in France from
RADIOSPARES; any equivalent component may be used). When the 12V power,
picked up from the fan supply, feeds the coil of the electromagnet, a small
rod pushes a lever that opens the shutter; this allows the CCD exposure
to be made. This shutter has been built and is used with PISCO and Aud'Ace.
It works perfectly. The manufacturing is simple. The electronic parts consist
only of a small switching transistor and a few discret components (the
final model will be simpler than the one shown in this picture). A significant
advantage of this design is that it needs only minor modifications of the
basic camera mechanical parts. All that is required is an increase by 15
mm of the squared tube of the camera case. It is directly mounted with
the bolts and column-nuts on the side foreseen for the camera without shutter.
This shutter is well adapted to deep sky imaging but it can also be used
for planetary imaging; the minimum exposure time is in the range 0,2 to
0,3 second.
The total cost of equipment is estimated at $50 (300 FF).
Pierre Thierry's prototype. A small servomotor
(for scale models) is used to move the mask in front of the CCD window.
The servomotor case can be seen, on the right, jutting out of the case
of the camera box. The servomotor commanding is done using one of the remaining
free bits (as for Thierry Maciaszek's design), this doesn't preclude use
of the other bits for other functions; for example to pilot the telescope.
It only needs an increase by 10 mm of the squared tube of the camera case
to implement this shutter. (As in the Thierry Maciaszek's design it is
the only mechanical part to change). Shaping the mask as a narrow slit,
it is possible to achieve very short exposures, well below 1/100 of a second.
This prototype has been used with success for the 11 August 1999 total
solar eclipse. The software used was a specially adapted version of Pisco.
The principle of this shutter may also be used to carry a filter wheel.
The total cost of equipment is estimated at $83 (500 FF).
Note : The availability of DACO
circular electromagnets that allows designing a very simple shutter.
You can find some other ideas for shutter at the page "Audine
Connection".
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