- Spring (April 12 2032) Spikes in Dec.
- Seems to be a bit loose. I tightened it up a bit and it got worse. I loosened it and the spikes disappeared. Hard to tell if it's too loose or too tight sometimes.
- Spring (Feb 16th 2022 or so) spikes again. I think that I'm seeing a pattern.
- Dec had it pretty bad, turned out to be mostly bad PA, but the worm was also pretty loose. Still needs some adjusting though.
- RA was also pretty bad, but came down after improved PA. I may have to adjust it's worm also.
- DEC Spike!
- Not bad really. I was still imaging getting 0.5 to 0.8 but once in a while DEC would spike. I think that it must be some sort of flexure or cable snag etc. I just noticed that the guide scope focuser was a bit wobbly. I tightened it, and we'll see how it goes tonight.
- Solved!
- I tried several things including all kinds of balancing tweaks, tightening guider and guider camera, worm adjustments. Finally I tried tightening up the Dec clutch, and boom, the spike is gone. It's a lot tighter than usual, so maybe it's time for a new clutch, or a clean one.
- RA spike every 15 min https://groups.io/g/Losmandy_users/topic/81796714#71124
- This is new, just started happening. It started in spring, not sure if the temp change triggered it, but the solution is to balance East. This is weird because I've never had to balance East before. I'm wondering if the temp change has something to do with it, and if the worm is too loose.
- Fixed!
- So the issue was that the RA was too loose. Maybe the warmer season made it looser because of temperature? I don't know, but tightening it up made the spikes disappear. Guiding was 0.78 to 1.05 -- not the best ever, but back to normal
Things that work
| Attempt | Comment |
|---|---|
| Save off a golden set of phd settings files and restore them before each session. | Extremely lame, but this has proven to be a huge help. I don't know what goes wrong with the files but this makes a huge difference. |
| Always run the assistant at the intersection of S and the equatorial | Everything works better here, so here's where you should do the assistant. |
| Use 3x smoothing for stars | Only thing this does is improve things, making it harder for PHD to lose track of the star. |
| Use 16 bit for guide camera | Sometimes this setting gets lost somehow. |
| Use PEC PHD algorithm | Finally got this to work. Increased the aggression a bit and set the work period to 239.34 (Try: 478.68) and RA guiding improved tremendously. It's important to unselect auto calculate period -- if not then things go haywire. |
| Calibrate at S equtorial intersection. | Don't calibrate anywhere else, just keep that calibration. I think that I knew this at one point, and forgot somehow. |
| Long guide exposures | Going from 1.5 to 2.0, and up to 4.0 I was getting better guide results every time I increased it. It went from .9 / .8 down to .7 / .6 -- This also allows for a great star image that is hard to lose |
| Blue Locktite on worm stop screw | I was having to adjust the worm every night, and during the night. After a post from the Losmandy Group, I added a drop of blue locktite to the screw, and now it seems pretty solid. I'm thinking of doing the same to the spring adjustment screw. |
| Really good worm adjustment | There are new instructions about the worm adjustment that seem to work really well. I think that I'm getting it. I've found that the worm needs to be adjusted frequently, maybe every night. So I'm attempting to 3d print gear covers that can flip up, and also have a hex key holder, so it's real easy to make the adjustment. It needs to be done after it's cooled down as well. The new method seems to work really well, and makes sense.
I think that what this does is allow the worm to be fairly perfectly adjusted normally by the stop screw. If some imperfection in the gear makes it tighter, then the spring will handle the give.
I was getting 0.8 -- 0.5 RMS last night using this even though I didn't realize that the DEC was way to tight.
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| Loose Dec worm | I adjust the worm at night when the temperature is the same as when I will be using it. I follow the Losmandy instructions, but make sure that it is very loose. In PHD2 I make sure to enable backlash compensation. In Gemini II I make sure to turn off backlash compensation. I've also tried one direction in PHD2, but have not come to a conclusion yet |
Worm Adjustment:
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The clutch can be tricky. It can be too tight or too loose. You have to get it just right basically by feel. When it's too tight, it seems to have a pretty jagged graph in phd2. Too loose and it seems to slip sometimes giving really good graph then a big jump. |
Star choice and settings:
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It's a tough balance between loosing a star, and having a good quality star. Many stars are multiple stars and as the phd selects the different stars it moves the scope. This makes for terrible guiding even if it looks pretty good because the guiding is so aggressive. The best thing to do is to find a tight star, and keep an eye on the red cross that phd put's at what it thinks is the center of the star. Smoothing of the image seems to help quite a bit with this |
Clutch Tightness
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I've got a torque wrench that I put on the end of the dec shaft to test this. Guiding was good lastnight around .78. Torque on the shaft is 25 inch lb to start movement, 13 to maintain. |
Things that I'm trying
| Attempt | Result | Comment |
|---|---|---|
| Switch to Sidereal for calibration, then back to King for guiding | I'm noticing that my n/s e/w are always off, and I'm wondering if it's because of King rate? I'd like to calibrate with it on sidereal and switch to King after. | |
| Set RA guide rate to 0.8 | Took several attempts to get it right. Need to make sure to set it in indi>Losmandy, PHD, and the Mount. Make sure to check the indi setting as sometimes it does not take. Maybe when it does not match the mount? | The idea here is to give phd more ooomf when guiding. I've seen guiding having a hard time keeping up. So far the results are inconclusive as I tried it with a guide scope setup at F10. So I tried this over a couple nights, and I'm not sure if it was seeing or something else, but the guiding was around 1.5 rms which is not that great. After putting the rate back down to 0.5, I was still getting around 1.5rms, so maybe just seeing conditions. |
| Add 2.5 TV PowerMate to the guide scope | The same night that I was getting around 1.5 RMS with the guide scope I tried adding a 2.5 power mate to the guider image train. This made a great improvement bringing performance down to 1.0 -- 0.79 RMS. Big improvement. Strangely the exposures were terrible, with double stars etc. Not sure what's going on here. I was careful to increase the focal length by 2.5x. Maybe PHD has a bug where it won't fully take an updated focal length? Not sure how that would work... Maybe I'll try and just make a new configuration from scratch... | Adding a 2.5 power mate to the guider image train to make things more precise. |
| Set RA guide rate to 1, and Dec to 0.5 | Only tried it once, and there were all kinds of problems, maybe not related | The idea here is to adjust for PHD2's single value for guide rate. Dec moves twice as fast as RA because it has twice as many teeth in it's gears |
| Switch the tracking rate to King | Seems to be working perfectly! |
The idea here is to adjust the guide rate to compensate for atmospheric refraction. I also should redo the polar alignment as it may affect that Tried it last night, and it was still on King, and seemed to be working just fine. Guiding assistant said that my polar align was just great. Something less than 1. I need to try more to understand if there is an issue with the King. |
Use binning with the guide camera when the moon is bright.
PHD2 is recommending this. I'm also having trouble finding stars on bright nights
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Haven't tried lately
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.. |
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