Handbook for the SXVR-M25C Issue 1 June 2009 The SXVR-M25C one-shot colour CCD camera Thank you for purchasing a Starlight Xpress CCD camera. We hope that you will be very satisfied with the results. The SXVR-M25C is an advanced, high-resolution one-shot colour cooled CCD camera, especially designed for astronomical imaging. It is a third generation version of the very popular SXV-M25C and incorporates many substantial improvements and extra features.
Handbook for the SXVR-M25C Issue 1 June 2009 The SXVR-M25C uses a Sony ICX453AK ‘Super HAD’ progressive scan CCD, with 3032 x 2016 x 7.4uM pixels in a 23.5 x 15mm active area. Super HAD devices have excellent quantum efficiency, with a broad spectral response peaking at around 60% in the green, and an extremely low dark current, well below that of any comparable CCD currently available.
Handbook for the SXVR-M25C Issue 1 June 2009 Installing the USB system: First, find a free USB socket on your PC and plug in the USB cable (do not connect the camera at this time). If you do not have a USB2 capable computer, it is normally possible to install a USB 2 card into an expansion slot. The next operation is to run the software installer from the CD ROM provided. Insert the CD into the computer and wait for Windows Explorer to open with the list of folders on the ROM.
Handbook for the SXVR-M25C Issue 1 June 2009 At the end of this process, the USB interface will be installed as a ‘BlockIOClass device’ and the camera software will be able to access it. You can confirm that the installation is complete by checking the status of the USB devices in the Windows ‘Device Manager’ (see above). Start up the Windows ‘Control Panel’ and select ‘System’.
Handbook for the SXVR-M25C Issue 1 June 2009 Now click on the camera icon at the top of the screen. If the USB connection is OK, a message box will inform you of the ‘Handle’ number for the SXVIO interface and various other version details etc. Click ‘OK’ and the main camera control panel will now be seen. As can be seen above, there is a CCD temperature monitoring window at the right hand side of the panel.
Handbook for the SXVR-M25C Issue 1 June 2009 Or 2) Create a ‘Pin hole’ lens by sticking a sheet of aluminium baking foil over the end of the 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.
Handbook for the SXVR-M25C Issue 1 June 2009 Point the camera + lens or pinhole towards a well-lit and clearly defined object some distance away. Now enter the ‘File’ menu in the SXV_M25C software and click on ‘SX camera interface’. Select an exposure time of 0.1 seconds and press ‘Take Photo’. After the exposure and download have completed (about 1 second) an image of some kind will appear on the computer monitor.
Handbook for the SXVR-M25C Issue 1 June 2009 Here is a small enlarged section of a daylight image which may be similar to your test image taken with a 50mm camera lens The visible grid encodes the colour information within the image data and will now be used to decode the red, green and blue image planes into a colour picture. To do this, open the ‘Colour’ header tag where you will see the ‘Synthesize colour image’ option. Click on this to open the colour synthesis control panel.
Handbook for the SXVR-M25C Issue 1 June 2009 4) Apply Anti-Alias: - Runs a special filter over the colour data to remove coloured artefacts around sharp edges. This is especially useful for cleaning up erratically coloured star images. 5) IR Filter Used? – Sets the colour balance to allow for the loss of infra-red content when using an IR blocking filter. 6) Stretching: - A selection of contrast-boosting options which are preset for various subjects.
Handbook for the SXVR-M25C Issue 1 June 2009 There is every reason to expect that the image will be reasonably well colour balanced, but if it is not, you can adjust the colour in the ‘Set Colour Balance’ dialog box (Under ‘Colour’ in the main menu). The colour balance controls seem complex, but are really quite easy to use. The most useful controls are the ‘Start’ and ‘Saturation Factor’ settings.
Handbook for the SXVR-M25C Issue 1 June 2009 Image enhancements: Your first image may be satisfactory, 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 the effects of image processing.
Handbook for the SXVR-M25C Issue 1 June 2009 When the par-focal eyepiece is fitted into the telescope drawtube, you can adjust the focus until the view is sharply defined and the object of interest is close to the field centre. On removing the eyepiece and fitting the CCD camera, the CCD will be very close to the focal plane of the telescope and should record the stars etc.
Handbook for the SXVR-M25C Issue 1 June 2009 In the case of the SXVR-M25C and a 2 arc seconds per pixel resolution, we get F = 0.0074 * 205920 / 2 = 664mm For a 200mm SCT, this is an F ratio of 664 / 200 = F3.32, which is rather less than can be achieved with the Meade converter and appropriate extension tube. However, moderate deviations from this focal length will not have a drastic effect and so any F ratio from about F4.5 to F6.3 will give good results.
Handbook for the SXVR-M25C Issue 1 June 2009 Although the peak value is sensitive to vibration and seeing, it tends towards a maximum as the focus is optimised. Carefully adjust the focus control on your telescope until the image is as sharp as possible and the peak value reaches a maximum. Wait for any vibration to die down before accepting the reading as reliable and watch out for bursts of bad seeing, which reduce the apparent focus quality.
Handbook for the SXVR-M25C Issue 1 June 2009 noise. Indeed, it is so low that subtracting a dark frame can actually INCREASE the noise in your images! This is because the statistical noise of the dark frame can exceed the ‘pattern noise’ from warm pixels and hence add to that of the subtracted result. If your test pictures have an exposure time of less than about 10 minutes (as above), then don’t bother with a dark frame, just ‘kill’ any hot pixels with your processing software.
Handbook for the SXVR-M25C Issue 1 June 2009 Relatively little nebulosity is visible at this time, but it will be revealed later. If you zoom in on the raw image, you will see that it has the regular grid of brighter and darker pixels, caused by the Bayer matrix filter grid on the CCD. Now apply the colour synthesis routine, using the same offsets that gave good results with the daylight image tests.
Handbook for the SXVR-M25C Issue 1 June 2009 The image should now look quite impressive and I hope that you are pleased with your first efforts! In many cases, a ‘Normal’ contrast stretch will give a good result, but may ‘burn out’ the bright regions and leave the faint parts of the image rather lacking in brightness. To combat this, many imagers will use a combination of ‘Normal’ and ‘Non-linear’ contrast stretches.
Handbook for the SXVR-M25C Issue 1 June 2009 at a rate proportional to the square root of the number of summations (summing 4 images will double the signal-to-noise), but different exposures must be used. Summing an image with itself will not improve the S/N ratio! Although I have concentrated on the use of a telescope for deep-sky imaging, do not forget that you have the option of using an ordinary camera lens for impressive widefield shots! A good quality 200mm F3.
Handbook for the SXVR-M25C Issue 1 June 2009 such as ‘Img23, Img24….’ and will be found in the ‘Autosave’ directory (or a subdirectory of Autosave, set up in the program defaults menu). The exposure time needed for good planetary images is such that the image histogram has a peak value at around 200 and does not extend much above 220 (Ignore the major peak near zero, due to the dark background).
Handbook for the SXVR-M25C Issue 1 June 2009 As a finishing touch, the application of a Median filter or a Weighted Mean Low Pass filter can be useful to smooth out the high frequency noise after a strong Unsharp Mask. As with deep-sky images, it is advantageous to sum planetary images together to improve the signal to noise ratio. In this case, the ‘averaging’ option should always be used, or the result is likely to exceed the dynamic range of the software and saturate the highlights.
Handbook for the SXVR-M25C Issue 1 June 2009 The autoguider installed on a 70mm refractor guide ‘scope in the author’s garden (the camera shown is the older SXVF version, but the connections are the same). To use the autoguider, please proceed as follows: 1) Having started the SXVR-M25C software, open the autoguider control panel by clicking on the autoguider menu button.
Handbook for the SXVR-M25C Issue 1 June 2009 The autoguider control panel with a guide star selected 2) Press the ‘Start’ button and a series of 1 second exposure guider images will begin to appear in the picture frame. If the images look too dim, use the ‘Stretch Image’ slider to increase its contrast and brightness until the noise begins to be visible.
Handbook for the SXVR-M25C Issue 1 June 2009 9) Now press ‘Go to main camera’ and the guider control panel will be replaced by the camera control panel. Set the required exposure time for the image (say 5 minutes) and press the ‘Autoguide next image’ button. The autoguider window will reappear and, after a few seconds, you should see error values appearing in the text windows at the top.
Handbook for the SXVR-M25C Issue 1 June 2009 The two serial connections are in the form of standard RS232 PC style plugs and provide TX, RX and Ground connections at RS232 levels. Access is via commands sent through the USB connection and, at the time of writing, is limited to any serial controls that are provided by the SXV software. It is expected that many more functions will be added as the software is upgraded.
Handbook for the SXVR-M25C Issue 1 June 2009 internal coating of matt white paint, which is placed over the objective of the telescope to provide an evenly illuminated surface. These can work well, but I prefer a simpler method, as follows: Most imaging sessions begin or end in twilight and so the dusk or dawn sky can provide a distributed source of light for a flat field. However, using the sky directly is likely to result in recording many unwanted stars, or patches of cloud etc.
Handbook for the SXVR-M25C Issue 1 June 2009 The SXVR-M25C is provided with two ports for use with accessories. The Autoguider output port is a 6 way RJ11 socket, which is compatible with the standard autoguider input of most telescope mounts. It provides 4 active-low opto-isolator outputs and a common return line, capable of sinking a minimum of 5mA per output.
Handbook for the SXVR-M25C Issue 1 June 2009 have small bottles of pure acetone. A bright light and a strong watchmakers eyeglass will also be found to be essential. Procedure: 1) Disconnect the lead from the camera head and remove it from the telescope. Place it on a table with the optical window facing downward. 2) Remove the two M3 screws and the M8 nut from the camera back plate and ease the plate out of the camera body. Unplug the fan lead from the camera PCB.
Handbook for the SXVR-M25C Issue 1 June 2009 ********************************************************************* Alternative Software Although we hope that you will be satisfied with our ‘SXV_hmf_usb’ software, other companies are offering alternative programs with more powerful processing functions. One of these is programs is ‘AstroArt’ by MSB software. You can purchase AstroArt from many dealers Worldwide and more information may be obtained from their web site at http://www.msb-astroart.
Handbook for the SXVR-M25C Issue 1 June 2009 Dear Observer, Thank you for purchasing a Starlight Xpress CCD Imaging System. We are confident that you will gain much satisfaction from this equipment, but please read carefully the accompanying instruction manual to ensure that you achieve the best performance that is capable of providing. As with most sophisticated equipment a certain amount of routine maintenance is necessary to keep the equipment operating at its optimum performance.