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Hi I just installed my EQ8-Rh in my observatory (astro-shed) today. There are not many videos on YouTube or other resources about the EQ8-Rh, so I thought I may have more luck here on good old AstroBin. I hope to get a chance to test it out over the next two days, if weather permits. I've been using a EQ6 Pro so far. I've upgraded, converted, tuned calibrated and taken it apart more time that I can even care to remember. I've managed to get good guiding, sometimes an RMS error below 0.3", but anything below 0.75" has been fantastic. It's erratic with huge spikes and jumps, and I'm imaging at the native focal length of my C9.25 at 2,350mm, so an RMS of 1" means I can just pack up and go to bed, so this mount is a dream come true. The first three questions on my mind are PEC training, PHD2 config and custom home position. The manual mentions PEC (and PPEC) training, but not what you need to do to run it. I have the Wifi version, and no hand controller, co I can't exactly click through the options. Any hints here would be great. The plan for PHD2 is to create a new config, run the calibration and guiding wizard. I'm not sure what they will say, but I've heard people say that the RA accuracy is better than what PHD2 can guide, so RA guiding should be disabled in PHD2. Is that how you run it? My observatory roof is too low to allow for the telescope to be in the standard upright home position:  I've not yet figured out how I can set an custom home position. I've not automated the roof yet, so it's not super important, but I would like to figure out how to do it. (Yes, I have it (temporarily) on modified version of my EQ6 mount.) Any other tips and advice would of course be much appreciated. Thanks and regards, Dan |
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First of all I assume this is the encoder version, and so that being said PPEC should be done automatically by the encoders as it runs, so nothing to do there, as long as the encoders are turned on. So as for guiding, just use the Hysteries in PHD for the DEC algorithm, and guide as normal with around 3 second guide exposures secondly, as for home position, this can be easily set in EQMOD or Green Swamp server software, just put it on the position you want to use and click save as hime position. It really simple, but you need to start with it at the native home position using the mounts autohome feature, then slew to the position you want to use and save it. |
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Fantastic, thank you, that answered pretty much all my questions in one go! All that makes sense and I think I know how to do all of it. Just two clarifications if I may: 1: Do you disable RA guiding in PHD2? 2: "encoders are turned on" - pardon my ignorance, but I didn't know they could be switched off. How do I make sure they are switched on? Thanks, Dan |
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Daniel Petzen: I’m not sure on this model if or how they can be turned off, I had the older model with freedom find encoders and they were rubbish and had them turned off all the time. As for switching off RA guiding, I would try with and without, to see which gives best results, sometimes the encoders and guiding will work against each other, so trial and error here I think. 👍🏻 |
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| @Daniel Petzen: Looking at your setup, you could probably also improve your cable management a bit. I assume that the grey cable going to the eagly is a LAN Cable? If you are fine with 100MBit/s you can use the RJ45 port in the saddle and the base to have a "thru-mount" connection. If the Eagle PC is running at 12V and if the acessories don't draw too much power you could try to use the internal power cabling as well. The unused USB and Power Ports on the saddle should be covered to protect them from dew. I would also recommend to remove the handles if this is a permanent setup. |
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Ah - talking about protection from dust and moisture: Don't forget to cover axis gears (at least DEC), if you live in a dusty / and or moist environment - its a design flaw of the mount that the gears are "open". I have created some 3d printable covers for my mount: https://www.thingiverse.com/thing:5965847 https://www.thingiverse.com/thing:5999458 |
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Hi Nico Re cable management: yes definitely. The network cable thru-mount is something I'll test, and covering the unused ports is a great idea. I'll definitely to that as well. The setup is a temporary solution until I have what I need to build the pier, but it may take a bit of time, so I'll have a look at removing the handles. As for power, this has been a long saga. I originally used the Eagle with a beefy 12V switched power supply for power distribution, but I then read (DarkFrame Optics), that the EQ mounts wanted 13.8 volt, so I got a separate power supply for my mount. I didn't notice a difference, but it was one less variable eliminated from the equation, so I kept it that way. I read in the manual that the EQ8 wants 12-16 volts and that "the higher the voltage, the better". I was planning on using my separate power supply at 13.8 volt for the EQ8. It would be good to know what your experience is with this and how you power it. Thanks, Dan |
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Nico Gärtner: Ouch. I didn't know that. I have a friend who does 3D printing. Would it be OK me (him) to download and print those? |
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I had a chance to do a test run. The calibration and guiding assistance showed great promise: ...but that was the end of the good news. No matter what I tried, I can't get good tracking. I though I had to do the PPEC training, but that made no difference. I was hoping it was PHD2 that was inaccurate, but when I did an unguided 4 minute exposure, the stars were elongated and NINA even re-slew the telescope. I've tried disabling guiding for RA and even Dec, but I can't get good guiding no matter what I do. I've given up and am now running with guiding enabled. This is what it looks like right now:  NINA has a bit longer guiding history:  If someone told me this was my EQ6 Pro on a good day, I'd believe that. The EQ8-Rh is a good mount. I know it is. I must be doing something seriously wrong. I enabled the decoders I did PPEC training and enabled PPEC I did a really good polar alignment I fastened all bolts and screws to lock it into position The mount is very stable and on a concrete platform There is now wind, no moon and Bortle 5 (19.68). The guide scope is the weak point and I would blame it first, but I got 0.28" RMS error with my EQ6 Pro with that guidescope, so I'm sure it's a given. I'll copy the PHD2 logs over later tonight. There may be some clues in them. I think I see patterns in the target circle (it gravitates to the upper right corner) and some cyclic errors in both RA and Dec (The NINA graph). It's supposed to be clear tomorrow night, so if anyone has any ideas, than I'd be more than happy to try them. Cheers, Dan |
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Daniel Petzen:Nico Gärtner: of course ... that's why I uploaded the designs to thingiverse  |
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Hey Dan, first of all a total RMS of 0.37" total RMS is not so bad.... From the PHD plot it looks like your mount is not reacting properly to the RA connection - this could have several reasons (mechanics and/or software). What software / ASCOM driver are you using to control the mount? Some recommendations: - Use Greenswamp Server as ASCOM driver - not the crappy Skywatcher Software and not the old-school EQMOD. - Turn off PPEC - Turn off the RA Encoders - Do a new guiding assistant run and a new calibration --> check if the results improve - if yes, turn on the encoders and repeat - if no, check your polar alignment once more and make sure that your guidescope is pointing to the same direction as your main scope --> check if the results improve - if yes, leave it as it is - if no, you should check mechanical issues (e.g high backlash in RA) I can't think of a scenario where PPEC and RA encoders should be enabled both - the encoders should effectively eliminate the periodic error, so there is nothing that the PPEC could do better... I also experimented a lot with PPEC (I have an EQ-8R without encoders), and at the end I just left it off, because it was just disturbing PHD. |
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Daniel Petzen: The EQ8 mounts are solid, and beefy, but have one big flaw, the backlash is absolutely awful, I see you did not run that test in your guiding assistant, you need to, that could well be your issue, it was with mine, it was so bad I scrapped my mount and bought a CEM70 |
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Nico Gärtner: The gears on these mounts are not open at all, that is just wrong, the only bit you can see is the silver disc wheel which is from the encoder, the rest is enclosed as much as any other mount… this is really not needed at all |
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| @AstroShed: The guiding assistant only tests the DEC backlash - thats indeed an issue of the EQ8 family, but it can be adjusted and fixed if required (I modified my DEC worm block to make it spring loaded). In this case the issue seems to be the RA axis and here backlash is usually not such a big issue. My guess is that the mount is "loosing" the RA corrections of PHD because of too many active "gizmos" in the mount (encoders, ppec, ...). |
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Nico Gärtner: I second this advice. 0.37" RMS is actually very good performance but it could be that PPEC and the RA encoder are interfering with one another so best to turn off PPEC. Your RA peak to peak 1.82 arc/sec so seems like the encoder is doing a very good job. You will also want to either increase your exposure time in PHD2 or use the delayed exposure setting. 1.5s is too fast. Mounts with little to no PE don't need corrections very often and benefit from larger periods between exposures. Try increasing to 5-8s and see if that helps. |
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Nico Gärtner: Yes spring loaded worms are the way to go, and they are availabe to buy now but very pricey… I agree about it not being an issue on the RA, but if the DEC is making a lot of corrections and moving back and fourth, this can really upset the RA and cause oscillation issues there too, so the DEC backlash can cause issues on the RA side too again I agree on not using PPEC and guiding and Encoders, it’s too much. |
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| @Reg Pratt : partly agree on the too short exposure setting: I am usually working with exposure times between 1.5 and 3s and it works fine for my setup - if I need to go for longer exposures then the seeing is so bad that I anyways cancel the session. If you want to do to fast guiding then the equipment also has to fit: - Imaging PC with decent speed (to process the guiding image fast) - USB3.0 guidecam - OAG (on fast optics) or fast and well aligned guidescope with at least 1/4 FL of the main optic - and... most importantly (very-) good seeing!!! |
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AstroShed:Nico Gärtner: My modification was super cheap and its working fine in my case. See here: https://www.thingiverse.com/thing:5999522 |
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AstroShed: I did run the backlash test third time:  DEC has a backlash, but I saw that it's not being compoensated for becuase the mount has absolute encoders (highlighted area). I couldn't find a way to tell PHD that I only have absolute encoders on RA only. I'm starting to think that I should tell PHD that the mount don't have absolutel encoders. |
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Reg Pratt: I didn't realise the PPEC was RA only. I can definitely see how that will make things worse. I'll disable that tonight. 1.5s was the sweetspot for my old mount. That will be completely different now. I'll put this on the list of things to test tonight. |
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Nico Gärtner: I had an RMS of about 0.65" during my first 1.5h session. RA was 0.46". I'll see if I can add the PHD2 logs to this response. I run Green Swamp Server (GSS). I connect GSS directly to the mount. I connect NINA to GSS using the ASCOM driver. No EQMOD or Sky-Watcher software in sight! I'm going to try out your testing. The list I have right now from all the advice is:Testing
Both
Ra
Dec
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Daniel Petzen:Reg Pratt: Exposure time is never an absolute rule I've just always read from people who have mounts with low PE that they tend to be happier with fewer spaced guiding corrections. Easy enough to try longer exposures and see how the mount reacts. Can always go back to 1.5s if need be. 3000ms of DEC backlash is a lot. I would wonder how much backlash can be present before the encoder has trouble compensating for it. It may be worth adjusting the DEC gears to try and reduce the backlash. Most importantly though... Have you collected any data with the new setup yet? How do the stars look? As stated before 0.3" RMS is nothing to scoff at. Your graph may not look pretty, especially at the scale you're viewing it at, but if your total rms is that low and your subs look good is there really a problem? It's really easy to look at graphs and go down rabbit holes of troubleshooting when it's not even needed (: |
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Nico Gärtner:AstroShed:Nico Gärtner: If it turns out that the Dec backlash is causing a problem, then I need to address that. What did you do exacly, Nico? Is the spring loaded Dec wormgear upgrade something liek this: Shibumi Astro Engineering Light-Duty DEC Axis Anti-Backlash Kit for EQ8 | First Light Optics Where does the 3D printed part fit in? Is it a compliment to the anti-backlash kit or an aletrnative? |
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Reg Pratt: My EQ6 has terrible tracking, so I guess that the very frequent exposures amde sense to be as low as 1.5s. I willd efinitely try longer exposure times tonight. Yes, 3s of DEC backlash is a lot. I compared it to the measurement of my "zero backlash" upgraded EQ6, and that had 500-700ms. This is very, very annoying. I have collected data, but I've not had a chance to process it. I did 37 4 minute exposures of NGC 1535 and 45 of Centaurus A. I did a Blink inspection jst now and I think that 5-10% of the images shows some minor tracking artefacts. This with a C9.25 at the native focal length of 2,350mm. This is the Eccentricity and FWHM for both sessions (NGC 1535 is first, and Centaurus a starts at index 38):  So, yes, this is good enough tracking to be able to use most of the frames. The reasons I ruined my finances buying this mount was that it was supposed to be an investment for the future: I really want to image very distant, minute, faint objects (in the same vein as @Gary Imm does). This was to be a significant investment in a mount that would be future proof and allow me to work with even longer focal lengths once I can afford it. It may work for me with what I have today, but this was supposed to open up completely new possibilities. Right now, I'm seriously worried about that. ...and also, I've been so busy responding to all great advice, that I forgot to say: Thank you all for your fantastic support and advice. I really appreciate it. |
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I forgot to attach the PHD2 log; Please find it attached: PHD2_GuideLog_2025-01-27_205755.txt I also did a stacking of NGC 1535 and Centaurus A. I only applied an unlinked STF throught the histogram transformation. No processing apart from the stacking calibration (yes, I know the vignetting is bad - I'm experiemnting a bit with back focus and calibration frames). Here they are, with warts and all: NGC1535, 2h 28m, drizzle x2:  Centaurus A, 3h, drizzle 2x:  There are only minor guiding artefacts, and it looks like the Centaurus A image has less guiding artefacts. Don't get me wrong; I'm happy with both images. A few hours more integration time tonight and they'll hopefully turn out quite good, but I was hoping for a much lower RMS error, which, in my experience, just subtly does wonders to the end result when it comes to clarity and details. |
