Starlight Xpress Lodestar-C User Manual

Lodestar C handbook Issue 1 May 2011

Handbook for the SX ‘Lodestar C’ one-shot colour imager and guide camera

Thank you for purchasing a Starlight Xpress ‘Lodestar C’ CCD camera. We hope that you will be very
pleased with the performance of this product.

The Lodestar C is a very compact imager / guider which is powered and operated via a single USB2.0
computer connection. It also provides an opto-isolated output connection for direct control of most
mounts, via their ‘Autoguider’ sockets. This output is compatible with the ‘ST4’ style of RJ12
connection and supplies 4 ‘pull down’ direction lines and a common return. Alternatively, you may
send the mount control signals via a serial connection from the guider control computer.

The Lodestar utilises a very sensitive Sony ‘ExView’ CCD (the ICX429AK) with an array of 752 x
580 pixels in a ‘half-inch’ format. Although the chip is not cooled, it has a very low dark signal and
very little readout noise, so it can be used to guide on faint stars that are beyond the reach of webcams
and CMOS chip based guide cameras.

The Lodestar specification:

CCD - Sony ICX429AK ExView colour ‘CMYK’ CCD
Pixel count - 752(H) x 580(V)
Pixel size - 8.6 x 8.3uM
Barrel size - 32mm dia. x 72mm long (1.25 inch eyepiece push fit size)
Barrel thread - 25.4mm x 0.75mm ‘CS’ mount lens thread
Input connection - ‘Mini B’ USB socket for USB2.0
Output connection - 5 way JST ‘ZH’ style 1.5mm pitch plug to RJ12 autoguider plug
Output type - Opto-isolated 4 lines (N,S,E & W) pull down with common return line
Download rate - Approx. 5 frames per second in full resolution 1x1 mode

Installing the Lodestar software:

A new installation will require the driver files SXVIO.sys and Generic.sys, plus the
SXVIO_Lodestar.inf file. If you run the ‘Setup.exe’ file on the supplied CD, it will install the drivers
and operating software automatically. If you are installing manually, copy these files into a convenient
folder on drive C and then connect the USB cable to the Lodestar. Point the installer at this folder when

Lodestar C handbook Issue 1 May 2011

it asks for the location of the drivers and you should see it set up the hardware as a ‘BlockIOClass’
device in Device Manager. If your computer seems to ‘lock up’ when installing generic.sys, you will
need to reboot and try installing the drivers in ‘Safe Mode’ (press F8 during boot up). This problem is a
bug in Windows XP SP3 and affects some, but not all, computers.

The Lodestar C control software is Lodestar.exe and the latest version may be downloaded from the
Starlight Xpress web site (http://www.starlight-xpress.co.uk), if necessary. Copy the exe file and dlls
into a folder on drive C and run the exe file to start the software. Alternatively, both ‘AstroArt’ and
‘MaximDL’ support the Lodestar C and may be preferred.
To install the SX software, unzip the files into a suitable folder (say ‘C:\CCD’ ) and then use a right
mouse click to send the .exe file to the Desktop to create an icon. Please note that Windows Vista and
Windows 7 will need to have ‘UAC’ disabled in the ‘User Accounts’, or the software will fail to run
correctly.

The USB and guider output connections

Colour imaging with the Lodestar C:

The Lodestar C uses a CCD with Cyan, Magenta, Yellow and Green ‘Secondary colour’ filters
integrated onto the silicon surface. These filters are arranged in a repeating grid of quads across the
CCD and so suitable software can translate the different pixel brightness into colour information and
create a true colour image from the monochrome data. This means that your ‘raw’ images are initially
black and white, with a ‘tiled’ look, owing to the filter grid. Conversion into colour is usually handled
by processing the raw images on the following day, when you can take time to optimise the colour
balance, saturation etc.

Taking your first images:

There are many ways in which the Lodestar C may be used to image the night sky, but all require some
kind of optical system ahead of the camera. Most owners will have a telescope already available and
this may well be suitable for taking good images with this camera, but you will find that a fast, short
focus ‘scope is much the best for your first experiments. If you have a small F5 refractor, then this will
work very well, but a typical F10 SCT should be fitted with a focal reducer to bring the F number down
to F6.3 or less. Using a short focus system will give strong images in short exposures and telescope
tracking problems will be minimised. You might even start with a ‘CS mount’ CCTV lens as a very
wide field optical system.

All CCD cameras have a high infrared sensitivity and this will give some strange colour results if it is
not removed by an infrared blocking filter. This is not too much of a problem with nebulae, as these
emit little infrared, but galaxies tend to show weak colour and daylight images of plants, grass etc. will

Lodestar C handbook Issue 1 May 2011

be very ‘washed out’ (chlorophyll reflects infrared very strongly). Also, the infrared focusing of many
lenses and refractors is poor, leading to fuzzy star images, if the IR is not filtered out. Please bear these
points in mind when choosing a lens or telescope, you may find that an infrared blocking filter is
essential for many such optics.

Once you have decided on your lens or telescope, attach the Lodestar C so that the CCD is close to the
focal plane and then point the ‘scope at a bright star. Start the Lodestar C software and select the
camera symbol from the top row of icons. The camera control panel should open, but if you see ‘USB
device not found’ please check that the Lodestar is connected correctly and, if so, try opening ‘Set
Program Defaults’ from the ‘File’ menu and select ‘Ignore VID/PID’. Save this setting and try opening
the camera dialog again.

Once you see the camera control panel, as above, select ‘Continuous Mode’, 1 second exposure and
‘Binned 2 x 1’. You can now press ‘Take Photo’ and you will see a steady stream of images appear in
the display panel. With luck, you will see one or two out of focus stars and you can then refine the
telescope focusing to get the sharpest possible result. Press ‘Esc’ to end the Continuous Mode
sequence.

Once the focus is optimum, switch the imaging mode to High Res (Progressive) and increase the
exposure time to about 30 seconds (switch off Continuous Mode). You should now see a star field with
a wide range of star brightness – you might also detect a hint of a ‘grid’ across the image, but this is
normal. The grid is caused by the filter matrix on the CCD, but will disappear when the images are
converted to colour.

I suggest that you now try imaging something with good colour, such as M42 or M27. M42 needs
about 60 seconds exposure at F5, while M27 will need about 5 minutes for a reasonable image density.
Save a selection of unprocessed image frames for experimenting with and practising your processing
techniques. Don’t spend much time colour processing at the ‘scope – this will waste good imaging
time! Once you have some good images to experiment with, you can try some colour processing, as
follows:
Open an image and then select ‘Set program defaults’. Make sure that the Pixel and Line offsets in
‘Camera Offsets’ are both unchecked – this affects the way that the colour filters on the CCD are
assumed to be organised and both ‘off’ is usually correct. You can confirm this by taking a daylight

Lodestar C handbook Issue 1 May 2011

image and confirming that the colours are essentially correct when using this setting. If the colours are
badly wrong, try other offsets until they are correct. It is possible that future firmware updates could
change the correct settings, so beware of this.

Now save the changes and then go to the main menu. Select ‘Colour’ followed by ‘Colour Synthesis’.