michael8554

In theory, RA is always being pushed in only one direction - slightly more, or slightly less, when guided. So RA backlash will always be taken up. Unlike Dec, which is guided in both directions, so Dec backlash routinely causes guide problems. But I understand that belt-drive mounts should be "perfectly" balanced. Which means in some positions the wind or cable drag could allow RA to "wobble" over the range of the backlash. Whereas slight RA imbalance would prevent that. Michael

Hi Paul You could try posting in the DIY Observatories section too. Michael

Alligators ate them all...... 😆 Some states it's illegal to own one ! Michael

Sounds like you have PHD2 AND APT both trying to "talk" to the mount at the same time. If so, this requires a Software Hub, such as ASCOM POTH or ASCOM DeviceHub, to mediate. Michael

Hi Paul You need to load the ASCOM Platform, followed by the Meade ASCOM driver. The are at least three ASCOM Meade LX200GPS drivers, the latest that fixes most deficiencies in the previous ones is: "Meade Autostar/Audiostar Project (October 2019) <- TRY THIS FIRST" which is on this page: https://ascom-standards.org/Downloads/ScopeDrivers.htm It's also known as the "Meade Generic Driver", it works with Autostar II for your mount, and for ETX etc mounts with the 497 Autostar. Next you need a connection between your PC and the mount, you haven't described how you have done this: A USB-to Serial Adapter, connected to a Meade #507 cable, plugged into one of the two RS232 ports on the mount. The RS232 adapter has to show as fault-free in Window Device Manager, note the number of the COM port it creates. After you have switched on the mount and Star Aligned, then open PHD2. Look for the Generic Driver in the mount section of the Equipment selection window, select the COM number, and connect. Michael

Probably, because the stars appear to "move faster" at Dec 9 than at Dec 60, so they are harder to guide, so a more erratic guide graph. Also Dec 9 is closer to the terrestrial horizon, down where the atmosphere is more turbulent. Michael

scitmon may be on the right track, on the 6th September did you enter 06/09 (probably wrong with an "American" mount) or 09/06 ? Michael

No surprise. A Flip Mirror is often used in these circumstances. For example: https://www.ebay.co.uk/itm/255067071462?mkevt=1&mkcid=1&mkrid=710-53481-19255-0&campid=5338353466&toolid=20006&4236=%26customid%3Ds%3AGS%3Bgc%3ACj0KCQjw-NaJBhDsARIsAAja6dOUahQa6nwbhmox8fooZLnuvXSRl8BkQYgdZ83eCZVTYavZ0VBPgCoaAiKWEALw_wcB%3Bpt%3A1%3Bchoc%3A2&customid=s%3AGS%3Bgc%3ACj0KCQjw-NaJBhDsARIsAAja6dOUahQa6nwbhmox8fooZLnuvXSRl8BkQYgdZ83eCZVTYavZ0VBPgCoaAiKWEALw_wcB%3Bpt%3A1%3Bchoc%3A1&gclid=Cj0KCQjw-NaJBhDsARIsAAja6dOUahQa6nwbhmox8fooZLnuvXSRl8BkQYgdZ83eCZVTYavZ0VBPgCoaAiKWEALw_wcB This allows the target to be framed with an eyepiece, then flipping the 45 degree mirror out of the light path reveals the imaging sensor. Michael

Probably one for vlaiv to answer, but here goes: A RA guide error of 1 arcsec at Dec = 0, and a guide error of 1 arcsec at Dec = 70, will have the same magnitude of effect on star shape. Are you asking whether guiding is EASIER at higher Dec ? Probably, as the stars appear to "move more slowly" in RA as Dec increases. Michael

Maybe tilted sensor ? Is the camera sealed by a clear glass slip that has become dislodged ? No expert on collimation, but shouldn't all the Airy Rings be offset, not just the inner rings ? Michael

Then it's a camera problem, not scope collimation ? Michael

I would use SharpCap to capture the video. Focus on a star. For the short duration of the video I don't think you need more than a rough PA. Pointing the scope to get the planet onto a tiny sensor at high FL is the hardest part. Michael

In that case you will need to set the Interval to at least double the exposure time, in the Intervalometer. Michael

It's really not clear whether the OP want's to do Planetary - "4000mm with Barlow" ?? Or DSO's ? Or both ? ASI1600 plus Filters and ASI533mc suggests it's DSO's. The 4/3rds ASI 1600 probably uses more than the coma-free area of the C8's imaging circle. So I expect a Celestron C8 Edge HD, a Meade 8" ACF, or an 8" Ritchie-Chretien should do the job. Michael

Pretty basic PHD2 questions, sounds like you've not read any of the PHD2 Help and How To guides available via the PHD2 Help menu. Such as https://openphdguiding.org/phd2-best-practices/ Also if you start using EQMOD, don't get caught out by the default ASCOM PulseGuide Setting of 0.1, up that to 0.5 or more:

You can test the Home position suggestion anytime, even indoors Then pretend to do a Star Alignment, you don't need stars. Michael

Hi Sean Not a CGX owner, but as I understand it: You position the mount into the Home position. And since you have changed so many parts, I believe you will need to set this as the Home position in the handbox. Then carry out a Star Alignment. If the mount will then not return to the Home position when commanded, and carries on past in RA, then there is a RA encoder problem. But I would have thought that should have prevented a successful Star Alignment. Michael

Thanks newbie, so 10 mins 38secs points to grit or a damaged spot on the worm. Definitely not PE, that is a 10 min 38sec cyclic drift in RA, not sudden spikes. Michael

From your GuideLog: In run 7 at 01:40am the RA spikes appear to be fairly regular at 10min 40 to 10 min 50 sec intervals. But more irregular in run 9 at 02:26am I can confirm they are not due to PHD2, they are due to the mount drive, you'll need to read posts concerning belt drive problems. I see as I write this that Steve has some suggestions 😆 Some settings you could improve: With ASCOM guiding you always Cal at Dec = 0, not Dec = 38, and use that for all targets that night. Your Cal had 5 steps of Dec Backlash before North Cal started to move the mount, which causes PHD2 to miscalculate the actual Dec guide speed. You must clear that Backlash by pulsing north until the guidestar moves, before Calibrating. Backlash Comp in PHD2 is disabled ? Run the PHD2 Guide Assistant to get a setting, and for recommended Minimum Move settings. Michael

Need to see your GuideLogs, but I can see from your screenshots: Dec Minimum Move is only correcting spikes bigger than about 2 arcsecs, much too high ! And the really large Dec excursion of 8 arcsecs is taking 12 x 6sec exposure = 24 seconds to correct. That large excursion is the result of Dec Backlash, the 24 secs to correct could be due to too-low guiderate and/or Dec Stiction. And corrections only every 6 secs doesn't help, try 2 second exposures. But it all starts with the PHD2 Calibration, if that isn't good, guiding will suffer. Seems to me you're focusing on the fine detail when your basics aren't right. Read the Help and How To guides via the PHD2 Help menu, start here: https://openphdguiding.org/phd2-best-practices/ Michael

Yes it has a wooden tripod. Maybe a poor description of the mount by a non-astro seller. But says "too big for me", suspicious. Michael

£475 including the mount is not bad, but there's no mention of the mount in the items for sale. Michael

The spec for the Neximage 5 is not very good for a dedicated Planetary Camera: "FPS - 6.23 to 52.37 at the lowest resolution, 0.71 to 5.99 at the highest resolution" But looks like you should be able to get at least 6fps with the right settings, which is fast enough to focus. What software are you using to drive the camera ? Michael

Hi Dean Dec = 90 is where the North Celestial Pole is, Polaris is located within 1 degree of the NCP. Dec = 0 is 90 degrees down from that, roughly where the moon is when it's south, not your local horizon. That's a good place, pointing south, to Calibrate for test purposes. But for all normal guiding you should calibrate "On Target" every time. Focus won't be the cause of your problem, it's just something else you need to refine. Michael

Hi Dean You are ST-4 guiding, which means a lot of important settings don't show in the Log. For instance, what Dec were you Calibrating at ? How good is your Polar Alignment ? The Guide Rate is unknown. Focus is poor, use the PHD2 Star Profile window to get the lowest HFD reading. Although you had a large Calibration Step = 1750 ms, PHD2 tried 61 Calibration steps, at 61 steps it gives up and shows the "not enough movement" error message. Cal should normally take 12 steps. A Calibration Step of 3000ms should give more movement, but will be longer than your average exposure of 2000 ms, so is not a sensible setting to use in practise. Hopefully an iOptron SkyGuider Pro user will have more experience of the Guide Rate and Cal Step settings. Michael