Starlight Xpress SXVF-H36 User Manual

Handbook for the SXVF-H36 Issue 1 August 2007

Starlight Xpress Ltd

SXVF-H36

CCD camera user manual

Thank you for purchasing a Starlight Xpress CCD camera. We hope that you will be
very satisfied with its performance. The SXVF-H36 is a very large format, high­resolution cooled CCD camera, especially designed for astronomical imaging. The
SXVF-H36 uses a Kodak KAI16000 Interline CCD, with 4008 x 2672 pixels in a

36.1mm x 24.05mm active area. The use of high performance microlenses on the
CCD surface gives the greatest possible throughput of light to the pixels and the
resulting QE is very good over the entire visible spectrum. Our new ‘F’ type USB2
interface hardware gives an exceptionally fast download speed of about 2 megapixels
per second, and so the SXVF-H36 can download a full resolution 16 bit image in only
12 seconds.

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Handbook for the SXVF-H36 Issue 1 August 2007

Please take a few minutes to study the contents of this manual, which will help you to
get the camera into operation quickly and without problems. I am sure that you want
to see some results as soon as possible, so please move on to the ‘Quick Start’ section,
which follows. A more detailed description of imaging techniques will be found in a
later part of this manual.

‘Quick Starting’ your SXVF-H36 system

In the shipping container you will find the following items:

1) The SXVF-H36 camera head.

2) A power supply module and cable.

3) A 3 metre USB2 camera cable.

4) An adaptor/spacer for 72mm x 1mm thread ‘Takahashi’ focuser assemblies.

5) An adaptor for 2” drawtubes and M42 ‘Pentax’ thread lenses.

6) A guider cable for ‘ST4’ style mount guiding inputs.

7) A CD with the ‘SXVF_H36’ software and manual.

You will also need a PC computer with Windows XP or Windows Vista. This
machine must have at least one USB2.0 port and at least 500 Megs of memory. If you
intend to view the finished images on its screen, then you will also need a graphics
card capable of displaying an image in a minimum of 1600 x 1200 pixels and 32 bit
colour. A medium specification Pentium with between 1GHz and 3GHz processor
speed is ideal. Please note that the SXVF-H36 is not designed for USB1.1 operation
and will give inferior results if used on USB1.1.

Connecting up:

Plug the 5 pin DIN connector into the socket on the power supply box, and plug the
power supply into the wall socket. The yellow LED on the power supply should light.

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Handbook for the SXVF-H36 Issue 1 August 2007

A rear view, showing the input and output connectors

Connect the miniature 4 way power plug to the socket on the rear of the camera and
screw the retaining ring into place. The LED on the rear of the camera will light a dim
yellow. The other connections should not be attached until after the software has been
installed.

Installing the software:

Switch on the computer and allow it to ‘boot up’. Once you have the system ready to
run, insert the program disk into your CD drive and select ‘Setup.exe’ if the disk does
not autostart. The initial installation is to set up the USB drivers required by the
SXVF electronics. The files SXVIO.sys and Generic.sys are copied to your
Windows\System32\Drivers folder and SXVIO_H36.inf is copied to Windows\Inf.
After this, the program ‘SXV_H36_usb.exe’ will be installed into your ‘CCD’
directory and a new directory called ‘Autosave’ will now exist on the same drive.
‘Autosave’ is where SXV_H36 will normally store its configuration file,
‘SXVH36.ini’, and any image files, which are recorded using the ‘Autosave’ mode in
SXV_H36 and saved in FITs format.

Please note that the version of SXVIO.sys supplied with your H36, is an improved
issue that should replace any copy that is already resident on your machine. Failure to

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Handbook for the SXVF-H36 Issue 1 August 2007

update will usually result in a tendency for white spots and streaks to appear in your
images.

You now need to set up the camera control defaults (shown above), as follows:
Start SXV-Hmf by clicking on the icon and select the ‘File’ menu. Now select ‘Set
program defaults’ and a window, which contains the various software settings, will
appear. Suggested starting defaults are as follows:

1) Background Image area Red (or as preferred)

2) FITS Unsigned Integer format Off

3) Star mask size (area used for photometry and guiding) 8 pixels

4) Telescope guiding output to ‘autoguider socket’

The other default settings are not important for current purposes and may be left as
the software start-up values for now.

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Handbook for the SXVF-H36 Issue 1 August 2007

Recording your first image:

We now have the camera and computer set up to take pictures, but an optical system
is needed to project an image onto the CCD surface. You could use your telescope,
but this introduces additional complications, which are best avoided at this early
stage. There are two simple options, one of which is available to everyone:

1) Attach a standard ‘M42’ SLR camera lens to the SXVF-H36, using the 27mm

spacer/adaptor to achieve approximately the correct focal distance.

2) Create a ‘Pin hole’ lens by sticking a sheet of aluminium baking foil over the end

of the lens adaptor and pricking its centre with a small pin.

If you use a normal lens, then stop it down to the smallest aperture number possible
(usually F22) as this will minimise focus problems and keep the light level reasonable
for daytime testing. The pin hole needs no such adjustments and will work
immediately, although somewhat fuzzily!

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Handbook for the SXVF-H36 Issue 1 August 2007

Point the camera + lens or pinhole, towards a well-lit and clearly defined object some
distance away. Now click on the camera icon in the toolbar of the SXV-H36 software
and the camera control panel will appear (see above). Select an exposure time of 0.1
seconds and press ‘Take photo’. After the exposure and download have completed
(between 8 and 10 seconds) an image of some kind will appear on the computer
monitor. It will probably be poorly focused and incorrectly exposed, but any sort of
image is better than none! In the case of the pinhole, all that you can experiment with
is the exposure time, but a camera lens can be adjusted for good focus and so you
might want to try this to judge the image quality that it is possible to achieve.

One potential problem with taking daylight images is the strong infrared response of
the SXVF-H36 as this will cause ‘soft focus’ with camera lenses. Soft focus is much
reduced by keeping the aperture setting below F8. Also, IR blocking filters are
available from various suppliers (True Technology, Edmunds etc.) and are
recommended for the best results when using a lens.

If you cannot record any kind of image, please check the following points:

1) Is the power LED on?

2) Does the software indicate that the camera is successfully connected? An attempt
to take a picture will fail with an error message if the USB is not properly installed. In
this case, try unplugging the USB cable and then reconnecting it after about 5
seconds. Restart the camera software and see if it can link now. If not, check in
Windows device manager (via ‘System’ in ‘Control Panel’) and see if the
BlockIOClass device is installed properly. If all looks OK, try checking the ‘Disable
VID/PID detection’ in the ‘Set program defaults’ menu and try again.

3) If you cannot find any way of making the camera work, please try using it with
another computer. This will confirm that the camera is OK, or otherwise, and you can

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then decide how to proceed. Also check on our web site to see if there are any updates
or information about your camera software that might help. The message board might
prove useful to ask for help with getting your camera operating properly.

Our guarantee ensures that any electrical faults are corrected quickly and at no cost
to the customer.

Enhancing your image:

Your first image may now be reasonably good, but it is unlikely to be as clear and
sharp as it could be. Improved focusing and exposure selection may correct these
shortcomings, and you may like to try them before applying any image enhancement
with the software. However, there will come a point when you say, ‘That’s the best
that I can get’ and you will want to experiment with various filters and contrast
operations. In the case of daylight images, the processing options are many, but there
are few that will improve the picture in a useful way.

The most useful of these are the ‘Normal Contrast Stretch’ and the ‘High Pass Low
Power’ filter. The high pass filter gives a moderate improvement in the image
sharpness, and this can be very effective on daylight images. Too much high pass
filtering results in dark borders around well-defined features and will increase the
‘noise’ in an image to unacceptable levels, but the ‘Low Power’ filter is close to
optimum and gives a nicely sharpened picture.

The ‘Contrast’ routines are used to brighten (or dull) the image highlights and
shadows. A ‘Normal’ stretch is a simple linear operation, where two pointers (the
‘black’ and ‘white’ limits) can be set at either side of the image histogram and used to
define new start and end points. The image data is then mathematically modified so
that any pixels that are to the left of the ‘black’ pointer are set to black and any pixels
to the right of the ‘white’ pointer are set to white. The pixels with values between the
pointers are modified to fit the new brightness distribution. Try experimenting with
the pointer positions until the image has a pleasing brightness and ‘crispness’.

At this point, you will have a working knowledge of how to take and process an
SXVF-H36 image. It is time to move on to astronomical imaging, which has its own,
unique, set of problems!

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Astronomical Imaging with the SXVF-H36

1) Getting the image onto the CCD:

It is essential to set up a good optical match between your H36 and your telescope.
The H36 has a very large CCD area and so many of the popular ‘SCT’ ‘scopes are
unable to provide good quality star images over the large chip. Because of this
limitation, the H36 was designed for use with a wide field highly corrected refractor,
such as the Takahashi FSQ106 or similar, and is supplied with an M72 spacer ring to
screw into the FSQ106 focus assembly. Here is a view of an SXVF-H36 attached to
the author’s FSQ, via the adaptor ring.

As a general guide, most CCD astronomers try to maintain an image scale of about 2
arc seconds per pixel for deep sky images. This matches the telescope resolution to
the CCD resolution and avoids ‘undersampling’ the image, which can result in square
stars and other unwanted effects. To calculate the optimum focal length required for
this condition to exist, you can use the following simple equation:

F = Pixel size * 205920 / Resolution (in arc seconds)

In the case of the SXVF-H36 and a 2 arc seconds per pixel resolution, we get

F = 0.0074 * 205920 / 2 = 762mm

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