michael8554

Apologies Shimonu, That was someone else's Guidelog I selected in Log Viewer. Michael

Have you had any Windows updates on the Tower PC ? Check all the USB power settings in Device Manager. Run the guidecam on its own with PHD2. If it runs okay add other equipment until it fails. Michael

The 120MM-mini sensor is 4.8mm x 3.6mm. The 290MM-mini sensor is 5.6mm x 3.2mm. So the 290 sensor is slightly wider, less high, so not significantly bigger. Michael

Redacted

A little more info would help. What exposure ? Which is RA, which is Dec ? I think from the Dither figures that RA is Blue ? There are excursions of up to 7.5arcsecs that are taking about 5 exposures to correct. Causing RA to fly over the other side of the axis up to 7.5arcsecs, and about 5 more exposures pass before RA is corrected. So I'd say RA is loose and has Stiction. If you have any sort of GuideLog it would be far more instructive than screenshots. Michael

The Focal length is 660mm. Measure 660mm from the front element, that's roughly where the DSLR sensor needs to be. Measure back from that point to the focuser, in the middle of its travel. Subtract 55mm for the DSLR + T-Ring, that's the length of extension tube you need. Get the closest available and fine-tune with the focuser. Michael

After further thought, I think that ASIAir is reporting Dec movement of the guide star. Since you have Dec guiding off, that movement in Dec is due to sudden Dec movement of the mount, maybe a cable snagging, tripod leg sinking, Alt adjustment loose etc etc. Michael

Realise now you only have a RA drive mount, so even if you'd not selected RA only, there shouldn't be any signal on the Dec axis. Post the ASIAir GuideLog, although it will be vague compared to PHD2, there may be a clue. Michael

I don't have ASIAir, but from your image, looks like it did a Dec Dither (red graph) ? Michael

I would have thought the "align success" message would come after the second alignment star in a 2 star alignment, not after the first ? Michael

From what I've seen from posts on this subject, and looking at the GuideLogs, if you're lucky ASIAir works as well as PHD2. If you're not lucky, the PHD2 guide settings not included in ASIAir may be the problem, plus missing information in the ASIAir version of the GuideLog makes diagnosis more difficult. Michael

Hi Fedele I've searched for GPC, but can't find anything Astro related, what is it ? As I understand it, sometimes it is impossible to focus with just a Binoviewer on its own, adding a Herschel wedge will only make it more difficult. I'd guess a 1.25" Hershel Wedge will have a shorter optical length than a 2" one. Michael

I'm sure you're right, but the autofocus sensors in the imaging sensor that cause the banding are there all the time, whatever mode you use. Michael

Like I said, an OAG won't make guiding any worse on a shorter FL OTA, that includes refractors and newtonians. Michael

There seem to be two types of banding on Canon DSLRs. The first is most noticeable during hot weather, and isn't like the OP's image, it's in many more regularly spaced horizontal bands. That was my experience with a 600D, it only showed up on hot summer evenings. The fewer bands in the image may be due to the second theory : Newer Canon DSLRs (700D onwards ?) have many more autofocus sensors, now set in horizontal bands buried in the sensor. Not noticeable on daytime snaps, but very visible in stretched long exposure astro images. Michael

Unfortunately your KSTARS GuideLog 23rd July is not compatible with PHD2 Log Viewer. It loads the text file, it graphically displays the Calibration (after I inserted a space between the Cal and Guide text), but the 3h 45min guide session will not display graphically. Regarding your Dec drift, try the real PHD2 and a Guide Assistant run of about 4 minutes. The Guidelog will show the unguided mount performance, Dec drift due to PA error, and any PE in the RA tracking. Michael

Could have been worse - you might have been married........... (sorry, couldn't stop myself). Michael

From your GuideLog 22nd July: PHD2 calculated your Guide Rate as RA = 5.1"/s. This is a bit low, Cal completed in 18 steps instead of about 12, normal rates would be 7.5 or more, so try increasing the Cal Step from 1800 to say 2500. The RA spikes that were shown in an earlier post. The first two are 4 minutes apart, which suggests a piece of grit in the worm. The third was 2 minutes later and coincided with adjustments to Hysteresis (why ?) and a sudden dip in camera output, resulting in Star Lost messages. Chicken or Egg ? The guidecam output was generally low despite 3 seconds exposures - effects of the fullish moon ? Michael

Taking the long view, an OAG is best for your 6SE + HEQ5, and won't make guiding any worse on a shorter FL OTAs. An OAG is comparable in price with a decent guidescope with suitably rigid rings, the guidecam will be more expensive, as it's best to go with a sensitive mono camera. I use A LodeStar 2, I'm not up to speed with suitable newer cameras. Michael

Understood, full moon is not an ideal testing condition ! Michael

I find that LiveView works on a bright star with a Bahtinov mask, no need to take long exposures. To verify that the GoTo after PAE has put the target in FOV, take a 30 second exposure at maximum ISO.

Hi Steve Continuing RA error in same direction could be Periodic Error. Post a GuideLog that has a Cal and some decent length guiding. Or you can run PGD2 Guide Assistant for a worm cycle, which turns off guiding and plots where RA and Dec are heading. That will show the amount of PE and the PA error. Michael

It does seem that the LX90 and LX200GPS have different Polar Home Positions. LX200GPS - upside down, with the finder under the scope. LX90 - right way up. Michael

Aligning and focusing the finder to be concentric with the imaging scope, pointed at a distant landmark, is a useful daytime activity. Then fine-tuning at night will be much easier. You can test your guidecam during the day using very fast exposures. Again focusing on a distant landmark will get you in the ballpark for fine adjustment on a star. Some recommend a pin-hole mask to get a daytime exposure. That's good for checking the camera works, but not focus, as it gives a massive depth of field, everything is in focus ! Michael

That should allow an accurate GoTo a nearby Target. From what I've just read, getting a PAE is not straightforward: "On the SynScan menus, the nearest equivalent of that sync function that I've discovered is called "PAE correction" (PAE being an acronym for Polar Alignment Error). It's two layers down on the "Utility" Menu: Utility>PAE>PAE correction. So, if you've used the Go-To and have an object selected but not centered, you'll need to go back up the menu ladder with the ESC key, select the Utility Menu, then down two steps, center the object and tap "Enter." I thought I would at least be able to choose the Utility menu just by using the "Menu" button, but alas, that is not the case. That button does nothing whatsoever unless I've gone to the top of the menu ladder with the ESC key."