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Handbook for the SXVR-H16

Issue 1 June 2009

22

If the stars are not circular, you may need to alter the guiding parameters, or
investigate the rigidity and drive performance of your mount. A lot of information
can be deduced by watching the behaviour of the guide star in the guider frame. If
it is continually moving between two locations, either side of the green cross, then
the RA or Dec pixels per second value is set too low. The higher these values are
set, the gentler the guiding becomes. Too low a value will cause an over-
aggressive correction to be made and result in oscillation of the star position
between two points.

Another source of guiding errors can be a too accurately balanced telescope
mount! Good balance can result in the telescope mount ‘bouncing’ between the
gear teeth as corrections are made. A simple fix is to add a weight of about 0.5kg
(1 pound) on the eastern end of the declination axis, so that there is always some
pressure acting against the gear teeth.

Getting a good result from an autoguider will often entail a lot of detective work
to eliminate the sources of gear error, telescope flexure, mirror shift etc., but the
final result is well worth the effort!

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Camera maintenance:

Very little maintenance is needed to keep the SXVR-H16 in excellent operating order,
however two problems, which are common to all CCD equipment, are likely to show
up on occasion. These are dust 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). 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.
Images taken with a large F ratio optical system are more likely to be affected by such
dirt, owing to the smaller and sharper shadows that they cast. There is no great
difficulty in removing such particles on the outside surface by the careful use of a lens
cleaning cloth or ‘air duster’ and so you should have little trouble with this aspect of
maintenance. Dust on the CCD faceplate is a much greater nuisance, as it casts very
sharply defined and dark shadows and it entails dismantling the camera to get rid of
it! To clean the CCD you will need a good quality lens cloth (no silicone) or tissues
and some high-grade isopropyl alcohol. A very suitable cloth is the ‘Micro-Fibre’
type marketed by PENTAX etc., and suitable alcohol is available from TANDY
(Radio Shack) etc. as tape head cleaning fluid. A bright light and a strong
watchmakers eyeglass will also be found 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.

Содержание SXVR-H16

Страница 1: ...a 15mm x 15mm 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 vi...

Страница 2: ...ics 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 SXV...

Страница 3: ...ll 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 selec...

Страница 4: ...nu and image panel appear If this is the first time that it has been run you will receive a warning about the lack of an ini file just click on OK and then open Set program defaults from the File menu...

Страница 5: ...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...

Страница 6: ...your camera and ambient conditions when you have some experience of using the system but do not try to operate at extreme cooling when the air temperature is high Recording your first image We now ha...

Страница 7: ...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 H16 software and the camera control panel will appear see above Sele...

Страница 8: ...eb 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 g...

Страница 9: ...opes 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...

Страница 10: ...an indicator Once you are happy with the focus quality achieved you might like to trim the settings of your par focal or flip mirror eyepiece to match the current camera position Although you can rea...

Страница 11: ...ime used during an imaging session As variations in ambient temperature can affect the dark signal it is best to take the dark frames within a few minutes of capturing your images For the same reason...

Страница 12: ...Handbook for the SXVR H16 Issue 1 June 2009 12 A 5 minute exposure many warm pixels are visible see the magnified view below...

Страница 13: ...he readout noise will be much reduced by the square root of the number of averaged darks and so this is one way to improve the situation but it needs a lot of imaging time to be devoted to gathering t...

Страница 14: ...rm pixels are modified the rest of the pixels are unaffected Yet another option is to sum several images that have a small degree of dither in their star alignment If the images are realigned on the s...

Страница 15: ...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 wide field shots A good quality 200mm F3 5 lens with an infrared blo...

Страница 16: ...ill 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 sub directory of Autosave...

Страница 17: ...otes 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 wher...

Страница 18: ...y 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 produc...

Страница 19: ...mbly mounted in front of the SXV camera or with a separate guide telescope rigidly mounted alongside your imaging telescope I personally use it with an 80mm aperture F5 inexpensive refractor as a guid...

Страница 20: ...n a 80mm refractor guide scope in the author s garden To use the autoguider please proceed as follows 1 Having started the SXVR H16 software open the autoguider control panel by clicking on the autogu...

Страница 21: ...cope and mount You have the option of manually selecting values or asking the software to attempt to determine what they should be This is done by pressing the Train button and waiting for the softwar...

Страница 22: ...ation 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 When small particles collect on the window th...

Страница 23: ...isturbed renew it with fresh compound before reassembling 7 Replace all the camera parts in reverse order and the job is done Dealing with condensation The SXVR H16 is designed to avoid condensation b...

Страница 24: ...ative to the CCD surface To make an adjustment slacken the appropriate set screw and then turn the adjacent cap head screw in the required direction Complete the adjustment by re tightening the set sc...

Страница 25: ...ly be used for normal purposes described in the standard operating instructions and within the relevant safety standards of the country where the equipment is used 2 Repairs under guarantee will be fr...

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