Handbook for SXV-M7C Issue 1 June 2004 Starlight Xpress Ltd SXV-M7C 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-M7C is a high-resolution ‘one shot colour’ cooled CCD camera, especially designed for astronomical imaging. Starlight Xpress Ltd was the first astronomical camera manufacturer to introduce one-shot colour to the market and we are still the leaders in this technology.
Handbook for SXV-M7C Issue 1 June 2004 available and the use of ‘secondary colour’ filters on the CCD surface gives the greatest possible throughput of light to the pixels. This camera is a next generation version of the parallel port driven MX7-C, but the use of an internal USB2 interface and the addition of an external guide camera option makes it considerably more effective. The synthesis of image data from a colour filter matrix CCD is somewhat complex and may be performed in several different ways.
Handbook for SXV-M7C Issue 1 June 2004 800 x 600 pixels and 65,000 colours. A medium specification Pentium with between 500MHz and 3GHz processor speed is ideal. 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.
Handbook for SXV-M7C Issue 1 June 2004 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.
Handbook for SXV-M7C Issue 1 June 2004 3) Interlaced image smoothing On 4) FITS Unsigned Integer format Off 5) Star mask size (area used for photometry and guiding) 8 pixels The other default settings are not important for current purposes and may be left as the software start-up values for now. 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.
Handbook for SXV-M7C 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.
Handbook for SXV-M7C Issue 1 June 2004 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 1 and 3 seconds) an image of some kind will appear on the computer monitor.
Handbook for SXV-M7C Issue 1 June 2004 After a few seconds a recognisable colour image should be displayed, although the colour ‘balance’ may need correction. This is especially true if your image was taken indoors with artificial lighting, which can make everything look very orange. If the colour image shows white spots or patches, where no colour is present, then the original exposure time was too long and some pixels are overloaded.
Handbook for SXV-M7C Issue 1 June 2004 Other options in the ‘Colour’ menu are ‘Apply Anti-Alias’ and ‘Adjust Chrominance’. We have already used the Anti-Alias filter as an option during colour synthesis, but it will be helpful for you to know its purpose. Basically, the AA filter is designed to remove colour errors at sharp transitions of brightness. Because of the spatial characteristics of the grid of filters on the CCD, a sharp edge in the image will overlay certain filters, but miss adjacent ones.
Handbook for SXV-M7C Issue 1 June 2004 At this point, you will have a working knowledge of how to take and process an SXVM7C image.
Handbook for SXV-M7C Issue 1 June 2004 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 SXV-M7C Issue 1 June 2004 Opinions vary as to the utility of flip mirrors. They are a convenient way to find and focus, but they add quite a bit of extra length between the camera and telescope. This can be very inconvenient with Newtonians, and not a lot better with SCTs, especially if the assembly is somewhat flexible.
Handbook for SXV-M7C Issue 1 June 2004 For a 200mm SCT, this is an F ratio of 844 / 200 = F4.22, which is easily achieved with the Meade converter and appropriate extension tube (as supplied with the converter). Moderate deviations from this focal length will not have a drastic effect and so any F ratio from about F3.3 to F6 will give good results. The same equation can be used to calculate the amplification required for good planetary images.
Handbook for SXV-M7C Issue 1 June 2004 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. Carefully adjust the focus control on your telescope until the image is as sharp as possible and the peak value reaches a maximum.
Handbook for SXV-M7C Issue 1 June 2004 processing the picture. The SXV-M7C generates very little dark signal and so dark frames are not essential for short exposures of less than a few minutes, but it is a good idea to record at least one for each exposure time used during an imaging session. As variations in ambient temperature will affect the dark signal, it is best to take the dark frames within a few minutes of capturing your images.
Handbook for SXV-M7C Issue 1 June 2004 2) You have already tested the colour synthesiser on a daylight image, so it should be set up correctly for your camera. Enter the ‘Colour’ menu and click on ‘Synthesise Colour Image’. Make sure that only the ‘Anti-Alias’ filter is selected and run the synthesis routine. 3) The resulting colour image will probably look faint and dull, with a strangely coloured background due to light pollution.
Handbook for SXV-M7C Issue 1 June 2004 pollution is orange or green in colour (sodium and mercury light) and may be removed by reducing the red and green offsets in the colour balance menu. It is best to look at the blue histogram and note the approximate offset of the main peak above zero. Now slide the ‘Offset’ of the Red histogram until the pointer is about the same distance below the main peak as is the blue peak above zero. Do the same for the Green histogram offset and then click on ‘Apply’.
Handbook for SXV-M7C Issue 1 June 2004 the noise will be strongly increased and dark rings will appear around the stars, but a ‘Median’ filter can remove odd speckles and a mild ‘Unsharp Mask’ (Radius 3, Power 1) will sharpen without too much increase in noise. Other things to try, include adjustment of the colour saturation and summing several images for a better signal to noise ratio.
Handbook for SXV-M7C Issue 1 June 2004 check the ‘Autosave Image’ checkbox near the bottom of the window. If you now click on ‘Take Picture’ the automatic sequence will begin and will not stop until you press a computer key. The images will be saved in FITs format with sequential names such as ‘Img23, Img24….’ and will be found in the ‘Autosave’ directory (or a subdirectory of Autosave, set up in the program defaults menu).
Handbook for SXV-M7C Issue 1 June 2004 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 SXV-M7C Issue 1 June 2004 ‘Alternative Slew Mode’ available, which uses the correlation of image areas, rather than a single star. This mode can be better in dense star fields. Another option is ‘Auto remove dark frame’. This is advisable with S&S images, as the slewing will mis-register the images with a single dark frame that is applied to the finished sequence. To use this option, you will need a dark frame, taken with the same exposure time as a single image from the sequence.
Handbook for SXV-M7C Issue 1 June 2004 a way that the errors are removed. Common flat field errors are due to dust motes on the camera window and vignetting effects in the optical system of the telescope. Dust motes act as ‘inverse pinholes’ and cast out-of-focus images of the telescope aperture onto the CCD chip, where they appear as shadow ‘do-nuts’. Most optical systems show some vignetting at the edges of the field, especially when focal reducers are used.
Handbook for SXV-M7C Issue 1 June 2004 flat field’ in the ‘Merge’ menu. The result should be an image with very little sign of the original artefacts and you can then process it to colour in the normal way. ******************************************************************** The accessory ports The SXV-M7C 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 SXV-M7C Issue 1 June 2004 STAR 2000 The SXV-M7C may be used with our patented self-guiding system ‘STAR 2000’. This can greatly ease the process of recording long exposure deep-sky images. Using ‘STAR 2000’ self-guiding with the SXV-M7C How S.T.A.R. 2000 works: S.T.A.R. 2000 is a unique and patented method of automatically controlling your telescope drives, while capturing a long exposure image with your Starlight Xpress CCD camera.
Handbook for SXV-M7C Issue 1 June 2004 What you need: To use S.T.A.R. 2000, you must have a telescope with ‘Auto guider’ capability. Most modern SCTs have this facility in the form of a 6 pin ‘RJ11’ telephone style connector on the mounting base or handset. If your ‘scope is ‘ST4 compatible’ it should work with S.T.A.R. 2000. Adaptors for other mounts, such as the Vixen Skysensor, are available from Starlight Xpress.
Handbook for SXV-M7C Issue 1 June 2004 1. Set ‘RA Pixels per sec’ and ‘Dec Pixels per sec’ to 5. 2. Set all backlash and hysteresis values to 0. 3. Set ‘Ignore drift < 1 pixel’ to OFF. 4. Set ‘70mS delay between direction changes’ to ON. 5. Set ‘Default guide training time’ to 2 secs. These values can be refined later, but should work reasonably well with most telescopes. You can now test communications between the computer and telescope mount, as follows: 1.
Handbook for SXV-M7C Issue 1 June 2004 The control panel will disappear and be replaced by the guider window, with a set of number boxes above it. The guider software will now attempt to centre an 80 x 40 pixel box around the guide star and this will appear in the guider window after a few seconds delay. The number boxes will also begin to show the star co-ordinates and the differential guiding error as each new guide field is displayed.
Handbook for SXV-M7C Issue 1 June 2004 The software includes an option to generate properly matched dark frames, by recording the number of guiding downloads executed during the taking of the image and using this to add the correct amount of amplifier glow to the resulting dark frame. To use this option, you must record the dark frame immediately after the ‘light frame’, or the download count will be lost.
Handbook for SXV-M7C Issue 1 June 2004 of your mount. This output is ‘active low’ (i.e. the control relays pull the guider inputs down to zero volts when applying a guide correction) and matches most of the autoguider inputs on commercial mounts. If ‘active high’ inputs are needed, or a very low control voltage drop is essential, then you will need to add a Starlight Xpress ‘relay box’ between the guider output and the input to the mount. Please contact your local distributor if a relay box is required.
Handbook for SXV-M7C 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 SXV-M7C Issue 1 June 2004 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 SXV-M7C Issue 1 June 2004 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). When small particles collect on the window they may not be noticed at all on deep sky (small F ratio) images, as they will be very much out of focus. However, if a powerful contrast boost of the image is carried out, they may well begin to show as the shadow ‘Do-nuts’ mentioned earlier.
Handbook for SXV-M7C Issue 1 June 2004 CCD window. If this becomes a problem, try to store the camera in a warm, dry place, or in a plastic lunch box containing a sachet of silica gel desiccant. N.B. DO NOT leave the camera switched on for long periods between uses. The cold CCD will collect ice by slow diffusion through any small leaks and this will become corrosive water on the cooler and CCD pins when the power is removed.
Handbook for SXV-M7C Power consumption: Issue 1 June 2004 220v / 110v AC @ 12 watts max., 12v DC @ 750mA Dear User, 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 SXV-M7C Issue 1 June 2004 3) The guarantee shall not apply to equipment damaged by fire, accident, wear an tear, misuse, unauthorised repairs, or modified in any way whatsoever, or damage suffered in transit to or from the Purchaser. 4) The Purchaser’s sole and exclusive rights under this guarantee is for repair, or at our discretion the replacement of the equipment or any part thereof, and no remedy to consequential loss or damage whatsoever.
