Handbook for the SXV-M25C Issue 1 June 2004 Starlight Xpress Ltd SXV-M25C SuperHAD 6Megapixel USB One-Shot Colour CCD camera User manual Thank you for purchasing a Starlight Xpress CCD camera. We hope that you will be very satisfied with the results. The SXV-M25C is an advanced, very high-resolution cooled CCD camera, especially designed for ‘One-Shot’ colour astronomical imaging. The features include a built-in, fully programmable, USB 2 super-fast computer interface (USB 1.
Handbook for the SXV-M25C Issue 1 June 2004 The USB 2 connection offers an excellent download speed, despite the very large number of pixels to be digitised. The full-frame download time with a 2GHz machine is approximately 16 seconds and binned 4x4 downloads take only 3 seconds, so finding and centring are quick and easy in this mode. If you have only a USB 1.1 connection on your computer, the download time is longer, but is still quite fast at around 30 seconds for a full resolution frame.
Handbook for the SXV-M25C Issue 1 June 2004 Installing the USB system: First, find a free USB socket on your PC and plug in the USB cable. If you do not have a USB capable computer, it is normally possible to install a USB 2 card into an expansion slot. Almost all machines manufactured after 1996 provide a pair of USB 1.1 sockets on the rear panel and either of these may be used if USB 1.1 is satisfactory.
Handbook for the SXV-M25C Issue 1 June 2004 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’. Now click on the tab labelled ‘Device Manager’ and all of the system devices will be displayed in a list (see above).
Handbook for the SXV-M25C Issue 1 June 2004 The camera rear panel Connect up the power supply and switch it on.
Handbook for the SXV-M25C Issue 1 June 2004 panel appear. 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. The main program window will now be seen. If you press the ‘Camera’ Icon button at the top left, the program will warn you that the ‘Program Defaults’ have not been set, but pressing ‘OK’ will allow you to continue.
Handbook for the SXV-M25C Issue 1 June 2004 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. 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 SXV_M25C software tool bar.
Handbook for the SXV-M25C Issue 1 June 2004 You can now select an exposure time of 0.1 seconds, followed by pressing of the ‘Take Photo’ button. After the exposure and download have completed (about 16 seconds) an image of some kind will appear on the computer monitor.
Handbook for the SXV-M25C Issue 1 June 2004 Please note that ONLY 1x1 binned images will decode to colour – the other modes are for focusing and acquisition only. If you cannot record any kind of image, please check the following points: 1) Ensure that the power indicator lamp is on and that the cables are properly home in their sockets. 2) If the screen is completely white, the image may be greatly overexposed. Try a shorter exposure time, or stop down your lens.
Handbook for the SXV-M25C Issue 1 June 2004 This includes various options for correcting the colour synthesis for variations in the lighting conditions, filters etc. Briefly, these items perform the following functions: 1) Daylight Image? – If an unfiltered lens is used, the infra-red content of the light will tend to produce a Green – Blue shift in the balance.
Handbook for the SXV-M25C Issue 1 June 2004 Now press the ‘Create Image’ button. After a couple of seconds, your raw mono image will be replaced by a full colour version. If the colour is roughly correct, then all is well. However, the colour decoding is reliant on the filter pattern being properly registered with the processing software and this can vary. If the colour is badly wrong, try opening the ‘Set program defaults’ dialog box and altering the ‘Pixel’ and ‘Line’ offsets.
Handbook for the SXV-M25C Issue 1 June 2004 The colour balance controls seem complex, but are really quite easy to use. The most useful controls are the ‘Start’ and ‘Saturation Factor’ settings. Saturation factor will simply vary the colour intensity, without any alteration of the colour balance, but the ‘Start’ settings for each colour will alter the colour rendering of the dimmer parts of the image.
Handbook for the SXV-M25C Issue 1 June 2004 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. In the case of daylight images, the processing options are many, but there are few that will improve the picture in a useful way.
Handbook for the SXV-M25C Issue 1 June 2004 filter for the reduction of light pollution and aberration effects and it is a valuable accessory to any imaging system.
Handbook for the SXV-M25C Issue 1 June 2004 computer will now display a continuous series of 128 x 128 pixel images in the focus window and you should see your selected star appear somewhere close to the centre. A ‘peak value’ (the value of the brightest pixel) will also be shown in the adjacent text box and this can be used as an indication of the focus accuracy. Although the peak value is sensitive to vibration and seeing, it tends towards a maximum as the focus is optimised.
Handbook for the SXV-M25C Issue 1 June 2004 M42 from a 5 minute exposure at F5 with the FSQ106 + IDAS filter Most competitive brands of CCD camera require a ‘dark frame’ to be subtracted from your images to achieve the best results. A dark frame is simply a picture which was taken with the same exposure as your ‘light frame’, but with the telescope objective covered, so that no light can enter.
Handbook for the SXV-M25C Issue 1 June 2004 ‘Flat fields’ are often recommended for optimising the results from your CCD camera. The purpose of a flat field is to compensate for uneven illumination and sensitivity of the CCD. In the case of the very large chip of the SXV-M25, it is likely that you will need to use flats to eliminate optical vignetting and so it is a good idea to get used to taking and using them.
Handbook for the SXV-M25C Issue 1 June 2004 To use your flat fields, they must first have a dark frame subtracted. Although this may appear to be unimportant with such brightly lit and short exposures, there is the ‘bias offset’ of the camera in each image and this can produce an error in the final correction. As we are mainly interested in the bias, any very short exposure dark frame will give a good result. The dark subtracted images should then be averaged together before use.
Handbook for the SXV-M25C Issue 1 June 2004 4) The image will now look quite impressive and I hope that you are pleased with your first efforts! Further small refinements are usually possible and you will become expert at judging the best way to achieve these as your experience increases. As a rough guide, the ‘Filters’ menu can be used to sharpen, soften or noise reduce the image.
Handbook for the SXV-M25C Issue 1 June 2004 Other things to try include summing several images for a better signal to noise ratio. This MUST be done AFTER colour synthesis, as summing raw images is very likely to destroy the filter grid pattern and so prevent the creation of a proper colour image. Summing can be done in the ‘Merge’ menu and involves loading the first processed image, selecting a reference point (a star) then loading the second image and finding the same star with the mouse.
Handbook for the SXV-M25C Issue 1 June 2004 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 change the S/N ratio! Another recent addition to the range of highly effective image enhancing software is a program called ‘Neat Image’. There is a free demo version for download at: http://www.neatimage.com/download.
Handbook for the SXV-M25C Issue 1 June 2004 Taking pictures of the planets: The SXV-M25 is not designed as a planetary camera, but it can be used quite successfully in the ‘sub-frame’ mode. Planetary imaging is in many ways quite different from deep sky imaging. Most deep sky objects are faint and relatively large, so a short focal length and a long exposure are needed, while planets are bright and very small, needing long focal lengths and short exposures.
Handbook for the SXV-M25C Issue 1 June 2004 ratio. This means that aggressive sharpening filters may be used without making the result look very noisy and so some of the effects of poor seeing can be neutralised. Try applying an ‘Unsharp Mask’ filter with a radius of 5 and a power of 5. This will greatly increase the visibility of any detail on the planet, but the optimum radius and power will have to be determined by experiment.
Handbook for the SXV-M25C Issue 1 June 2004 A very useful accessory is the add-on autoguider head, which takes its power and control signals directly from the SXV camera, via the 18 way socket on its rear panel. The autoguider is only 1.25” in diameter and has a video style ‘CS’ mount thread in its nose, so video lenses may be attached.
Handbook for the SXV-M25C Issue 1 June 2004 The autoguider installed on a 80mm refractor guide ‘scope in the author’s garden To use the autoguider, please proceed as follows: 1) Having started the SXV-M25C software, open the autoguider control panel by clicking on the autoguider menu button.
Handbook for the SXV-M25C Issue 1 June 2004 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 SXV-M25C Issue 1 June 2004 calculations. The training will also determine the angle at which the guide camera is oriented with respect to the RA and Dec axes. If you do not wish to train the system at this time, the default values of 6 pixels per second will serve as a starting point. 9) Now press ‘Go to main camera’ and the guider control panel will be replaced by the camera control panel.
Handbook for the SXV-M25C Issue 1 June 2004 box and cables are available as an accessory and may be chained in series with the autoguider cable, when the guider is in use, or may be used on its own. 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.
Handbook for the SXV-M25C Issue 1 June 2004 reduce its resolution. However, generally, these are more useful for finding faint objects, than for imaging, as the colour information is lost in all these modes. . ********************************************************************* The SXV-M25C accessory ports The SXV-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.
Handbook for the SXV-M25C Issue 1 June 2004 ********************************************************************* Camera maintenance: Very little maintenance is needed to keep the SXV-M25C in excellent operating order, however two problems, which are common to all CCD equipment, might show up on occasion. These are dust particles and condensation. Removing Dust: 1) Dust can be deposited on either the optical window (not a big problem to cure), or on the CCD faceplate (difficult to eliminate entirely).
Handbook for the SXV-M25C Issue 1 June 2004 6) Before re-assembly, make certain that the inside surface of the front window is also clean, and then carefully replace the camera front barrel and screw it into place. (If the heat sink seal is disturbed, renew it with fresh compound before reassembling). 7) Replace all the camera parts in reverse order and the job is done.
Handbook for the SXV-M25C Issue 1 June 2004 Readout noise: Approx. 7e RMS typical, 12e max. Back focal distance: The CCD is approximately 18mm from the barrel front. Camera size: 75mm diameter x 100mm long 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.
Handbook for the SXV-M25C Web site: http://www.starlight-xpress.co.
