Frequently asked questions about the
Artemis large format cameras.
What are the
advantages of set point cooling?
How are the CCDs
levelled in the cameras?
Is there a SDK for the
cameras?
What operating systems are
supported?
How are the
cameras connected to telescopes/filter
wheels?
What size filters are
needed?
Answers
What are the
advantages of set point cooling?
Previous
Artemis cameras using Sony CCDs were
cooled but not regulated and was the CCD
temperature not measured. This
means its not possible to take darks
frames which match image frames.
The Sony CCDs have very low thermal
current so this is not an issue and
expensive thermal regulation is not
used. The Kodak CCD used in the
large format cameras have higher thermal
current and we feel that temperature
regulation and measurement is important
in order to take good dark frames to use
in calibration.
As a side
issue Kodak specify maximum heating and
cooling rates for there sensors.
We are able to meet these specs with a
regulated cooling system but would not
be able to with a simple on/off system.
Finally by
measuring the CCD temperature the user
is able to know for sure how effective
the cooling is rather than rely on an
approx value given in the
specifications.
Is there a SDK for the
cameras?
Yes.
It can be found on the downloads
section. Examples are given in C++
and can be compiled under windows.
How are the CCDs
levelled in the cameras?
With large
CCDs it is important that the sensor is
orthogonal with the camera case so it
will be coincident with the image plane.
During assembly the CCD position is
measured to 0.01mm at its four corners.
If required shims are added to ensure
the sensor and case are aligned.
As part of QC a selection on cameras are
further tested using an artificial star
and a good quality camera lens at f3.
The cameras do not provide the facility
for the user to adjust this level as it
not necessary and could lead the the
camera needing to be returned.
What operating systems
are supported?
The
cameras have been tested under Windows
XP and Vista. Drivers are included
for Windows 98 but performance is not
guaranteed. Linux and Mac are not
supported at this time but we do provide
help for users wishing to write drivers
for these OS.
How are the
cameras connected to telescopes/filterwheels?
The
Art4041 has a standard female T thread
which is compatable with many adaptors.
We sell a low profile Male to Male T
thread to convert the camera to a Male T
thread which can be screwed into many
filter wheels.
The
Art11002 has a larger sensor and need a
bigger aperture than can be provided by
a T thread. We have chosen
M54 x 0.75 which is a thread type used
by Takahashi and compatible with true
tech filter wheels.
http://www.trutek-uk.com/cwss/ss50/ss50.htm
Again an adaptor is sold to couple
directly with a true tech filter wheel.
Also a M54 to 2" push fit can be
provided.
What size filters
are needed?
The
Art4021 can be used with 1.25inch
filters. The Art11002 requires 2"
or 50mm filters. Again see
http://www.trutek-uk.com/cwss/ss50/ss50.htm
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