Santa Barbara Instrument
Group (SBIG) ST-2000XM
The ST-2000XM is an outstanding CCD camera to use for imaging the sun. It's high dynamic range,
low noise and 2MP size produces large, detailed
images.
I use this camera due to its smaller array and
and large pixel count. The ST2K
yields a larger image size on the chip and therefore utilizes more
of the detector than the other SBIG cameras. It does not need a Barlow to
magnify the scale. It
fills over half of the detector with the solar image. The 7.4 micron pixels
offer a 1.75" resolution which is often better than the seeing in
Maryland will allow. Other considerations were faster download times
(4.5 sec), weight and of course, it's cost.
The 2000XM (X=USB, M=microlens) I use is equipped with
the KAI-2020M chip. This newer array, introduced in July 2004, has
much lower read noise, dark current and bright pixels than the older
version of this camera. This is important when processing images as
it makes it easier to discern the details of the shot.
I can get the entire disk on the
chip when using the f/10 SolarMax 90 scope. Focus images are shot at .001 second. Grab
images are shot between .001 and .004 second. I save them in their
native SBIG format and look them over for clarity once the session
is finished. Only a few of the 100 or so images taken each session will be clear due to seeing.
ST-2000XM, 3" extension
and JMI NGF-C Focuser
Not all SBIG cameras are equipped
with the ultra-fast
shutter speeds needed for Ha photos. Only three SBIG cameras with electronic shutters currently
support millisecond speeds: The STL-11000M ($9000),
STL-4020M ($6700) and the
ST-2000XM ($3200).
I once tested the 4020M and found that the 2000XM produced a better
image due to the larger image scale.
Camera Specifications
|
Pixel Array
Best fit depends on FL of scope |
1600 x 1200 pixels,
11.8 x 8.9 mm |
|
Total Pixels
More is usually better |
1.92 million |
|
Pixel Size
Smaller is usually better for resolution |
7.4 x 7.4 microns |
|
Shutter
Electronic is best for Ha |
Electromechanical |
|
Minimum
Shutter Speed
.001 is a must for unfiltered Ha |
.001 |
|
Binning Modes
Simulated FOV is 1x1 |
1 x 1, 2 x 2, 3 x 3 |
|
Download Time
USB 1.1 |
~ 4.5 seconds |
|
Resolution per Pixel
Seeing usually allows 2.0 and up |
1.73" |
Simulated
Field of View (FOV)
The SolarMax 90 FOV is 38 arc seconds high x 51 arc seconds wide.
Using a TV-102, SM90 and BF15 you'll get a field of view of 35 x 46
. The sun is 30 x 30 arc seconds in diameter. You'll need a good
tracking mount to keep it on the chip. Any misalignment will cause
the sun to drift and make you constantly reposition the
image.
Image taken through the
ST-2000XM
See
http://www.sungazer.net/ccdprocess.html
for processing information and colorizing using Adobe PhotoShop CS.
