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Se oscilla troppo, o è il seeing o la montatura non è ben bilanciata.
Leggi questo estratto dal manuale di maxim:
Autoguider Troubleshooting
First of all make sure that the autoguider camera works reliably as a basic imager, by using the Focus tab in continuous mode.
Autoguider Oscillates
If the guide star seems to bounce back and forth rapidly, your calibration is wrong. Try increasing the Cal. Time setting so that the calibration moves the star a larger distance on the CCD sensor. If it only moves a small distance, mechanical problems like backlash may make the measurements inaccurate.
Also try reducing the Aggressiveness setting in the Guide tab Settings dialog box. Generally speaking, correcting 100% of the error (Aggressiveness = 10) is unwise because in theory it is on the critical edge of instability. A lower setting will make the autoguider corrections more stable and prevent overcorrection. We recommend using a setting no higher than 8.
You can try experimenting with the backlash settings. Whenever the mount is reversed in direction, an extra long pulse is sent to run out any backlash. The amount of time of this extra pulse is entered in seconds. Backlash compensation is usually only required on the Declination axis since the sidereal tracking normally runs out the backlash in RA. Be careful, however, not to set the backlash time too high – that will make the situation much worse. It is far better to set it too low than too high.
Some mounts, such as Losmandy controllers, do not like RA and Dec corrections occurring right after one another. You can set an extra time delay between these corrections using the Guide tab Settings dialog More… button.
Other “finesse” features are available on the More Settings page. You can turn off corrections for a particular direction. This is useful on some mounts for suppressing Declination reversals; this can be helpful on mounts that have stiction problems with their declination drive gears. You can also set minimum move and maximum move parameters. Be careful when playing with these settings since you can render the autoguider non-functional with incorrect settings!
Telescope Not Moving
To verify whether your telescope is being commanded to move during guiding, click the Move button on the Guide tab. Use the Manual Control to move the motors in several second bursts. You should be able to see motion of the image. If you are doing this indoors, on most telescope mounts you can hear a difference in the motor noise levels when you click a button (you may need to hold your ear up to the motor).
If the telescope does not move, check the cables and software configuration (see below).
Relay Operation
If the mMost autoguider problems are simply CCD camera problems; please make sure you can successfully image with the guiding camera using the Focus Tab before proceedingotors are not working, check that the Control Via on the Guide tab Settings dialog is set properly. If you are using the guider relays, be sure they are selected. If you are controlling via the Telescope control, make sure that is selected. The LPT settings are used for control via the PC parallel port; certain homebrew configurations work this way. The COM port modes are generally for advanced use only; they are not intended for LX200 control.
Miscellaneous Tips
For some mounts, you must set the guide rate manually. The maximum usable rate is 1X sidereal. If your mount does not drift quickly, then 0.1X is recommended; otherwise use a value between 1X and 0.1X.
Use a calibration time that causes the star to move ~20 pixels or more across the CCD array. This is to ensure an accurate measurement. You may have to increase this number if your mount has significant backlash. Watch the motion of the star during calibration to ensure that it travels in an “L” shape and returns close to the starting position after the cycle is complete.
Make sure that any backlash compensation in the mount is turned off.
If you are not sure how to set the Guide tab’s Backlash settings, then set them to zero. If your mount takes one second to reverse directions, then the backlash setting should be set below one second; never higher. Note that backlash is generally only an issue in Declination, since sidereal tracking takes care of it in Right Ascension.
For most mounts, you should set the Aggressiveness to somewhere between 5 and 8.
Some mounts have significant stiction on the Declination axis. Stiction causes the mount to continue to move forwards briefly when you reverse directions. A common solution is to disable declination corrections in one direction only. You should disable the direction that pushes in the same direction as the average drift. You can disable one direction using the Guide Tab, Settings, More. Some observers even deliberately offset their polar alignment slightly to ensure a very slow drift.
On most telescopes, the Right Ascension drive likes to have some load pushing against sidereal tracking. If the mount is balanced such that it is pulling the mount forwards slightly, the gear teeth may bounce back and forth resulting in terrible guiding that cannot be corrected by an autoguider. Be sure to always balance the telescope such that it “lifting the weight” rather than “allowing it to fall”. Note that this may require balancing the telescope differently when it is pointed East versus West.
Treat each axis as a separate problem to be solved. It might be working fine in RA and overshooting in Dec, etc. Often the solution for one axis is different from the other.
You can adjust the mount response in RA and Dec separately by tweaking the manual calibration parameters. The number displayed is the rate of star movement during tracking in pixels per second. If the axis is overcorrecting, increase the number; if it is undercorrecting, decrease the number.
Try adjusting the rate at which updates are sent to the mount. Some mounts work best with multiple updates per second, while others work better with a slower update rate. For example, LX200 mounts generally work best with a 3 second update rate. In most cases you can simply increase the guider exposure time to slow down the updates; however, a delay-after-correction function is available if needed.
If you are using the track log to analyze guider operation, it is a good idea to rotate the camera so that the RA is parallel to the camera X axis. This is not required for guiding, but it does make the log easier to interpret.
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Strumentazione fissa:In origine era Astrosib RC360mm F 8.0, ma da 2006 sono bloccato per mancanza del telescopio, ancora non riparato. Provvisoriamente ho
Meade 14" F 10 montato su GM2000QCI (ottima montatura)+ ST8XME
Strumentazione portatile:
Gm8 losmandy + APO Tripletto 102 F 7.0 + Sigma 3200ME + Sbig 237a
Cieli sereni e non inquinati.
Angeli e ministri di Grazia difendeteci.
Ettore
Astrofilo66
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