This is fantastic James! Seems pretty similar to the results I get from my Z81 and EdgeHD 8 on the EQ6-R. I do need to adjust my worm carriers every now and then depending on the extreme temperature differences. June - August, we have 90F+ temps and in December-February we can see -10F temps. The temps seem to really effect the worm drives.
I'll have to keep track of these numbers going forward as we enter the Summer months. I suspect I'll be referring to your and Astrobloke's tune-up videos once my warranty expires.
Very interesting to see the statistical information from PHD2 analysed and nicely presented in easy to understand graph form. I think you can feel pretty happy with below 0.53 total RMS error - the EQ-R can wait a bit longer :)
Haha. The $10,000 price tag will definitely make me wait. Plus, I'd have to lug that beast in and out since I don't have a permanent setup. How much are those 0.2 arc-sec RMS worth? The open question is whether those 0.2 arc-sec actually lead to smaller FWHM - you can't beat seeing! Thanks for watching, Logan!
@@Aero19612 yes indeed. In good seeing my CEM120 can be down at 0.28 but in bad up to 0.8 so maybe better to invest in a property on top of a mountain 🤣
Very in-depth as usual. I've had my EQ6R-Pro for about 2 years which replaced an AVX. I have two Explore Scientific telescopes - ED80 FCD100 plus Orion 50mm guidescope & ED127 FCD100 plus ZWO OAC. Neither is pushing this mount's weight limit and the guiding for both scopes is fairly equal even through the stars in the OAG are elongated and horrible. Normally, I expect a combined RMS ~0.5" unless seeing is bad or setup is poor. Weight balance issues can easily double the error - nights with great guiding prior to meridian flip followed by bad guiding after or vice versa. I've found like many others have suggested in the forums, my inconsistent guiding performance can be improved with a slight imbalance to reduce backlash. I've also heard not being exactly polar aligned also helps but I've found my best DEC performance with nearly perfect PA. I've had successful operation down to -34 C (-30 F). All in all, it's a great mount for the price!
Totally agree, Greg. This is a very good mount for the money. If you want to shell out the additional $8,000 for an EQ8-R, for the additional 0.2 arc-sec, that's cool. But I'm pretty pleased with the performance, especially coming from the CGEM. Thanks for watching!
Great analysis. I use this mount with a C8, w/o going through the numbers your results "feel" about what I observe (N.I.N.A + PHD2 + GSS with alternete PEC algorithm). However for my EQ6R-Pro I had to do the worm gear adjustment shown in Cuiv's and Astrobloke's videos to tighten up the backlash. Made a HUGE difference. The observation of roof-top affecting guiding is also very interesting, In my case I've often observed guiding to be terrible until sometime after the meridian flip.. Earlier in the night I'm often pointed across a roof, perhaps I've the same thing. Or maybe one side of the pier is better than the other? Great video!
Hey Bruce. Thanks for the feedback. Things may loosen over time and then I'll have to do the adjustments you're talking about. As you say, the location on the worm gear has an effect as well. Thanks for watching!
@@Aero19612 lol, it's a great mount! However, about 6 weeks ago, I put my edge11 on the EQ6 to give it a try even though it's at or above the weight limit, and with good balance I was getting 0.4rms using the OAG. Eq6 is a great mount, better than my old cgx-l honestly. I still haven't gotten around to making any videos yet but maybe I should regarding some super tuning I have done to my eq6. Do you still have your chem or did you sell it?
No. Still have the CGEM. Toying with the idea of using it as a second rig for a short focal length scope (e.g., Redcat) that can tolerate “poor” guiding. Yeah, make an EQ6 tuning video. There several out there, but a different approach and suggestions are valuable.
Great work. I have just tweaked the BL on my EQ6R. Funny enough I ended up giving it a bit more slack. I connected a amp-meter to it and I could see at one side it was drawing more. From 2 nights of testing it seems like I got rid of some spikes and my RMS went 0,2 down. For me it seems like a lot of EQ6Rs are very stiff from the factory. First thing I "tweaked" was to loosen the axis and tighten them again, but not factory tight, that made it easier to balance (smooooth). Second is the thing with the amp-meter. A bit more technical, but seemed to solve a problem that have annoyed me a long time.
Yes, the RA axis is a bit stiff on mine. I will try to make adjustments to loosen things up a bit to make balancing more accurate. Will have a look at the amp meter. Thanks for watching!
@@fredmercury1314 Overall I really like it. Great payload for the size. Solid. What I don't like 1. The bolts are really hard to access to fix it to the tri-pier so if you are setting up each night, it's really frustrating. Some people tap holes in the pier top plate. 2. I still have some guiding spikes in RA and Dec. OVerall RMS is in the 0.4-0.6 which is great, but sometimes spikes up to 2.6 or so in each axis very briefly and I don't know why. Through the mount cabling is really really nice.
Interesting as always. I have an AZEQ6GT and I’ve been pleased with it. I now have a permanent setup on a pier. My total RMS for my 65 and 102 refractors is excellent. Last night with my 192 it was less than 0.3! I think it was very good seeing, but it’s always good. When I mount my Edge 800 it all goes to pieces. My PA is spot on and I use a QSI660 with built in OAG plus the Celestron 0.7x reducer. At 1400mm I get bad star trails even on short exposures of around 10 seconds and guiding just can’t deal with the corrections needed. I run the rig from a battery so I’m guessing it’s either not enough power or I need to strip the mount down and re grease the bearings etc. I know the mount is stiff in RA because getting balance sorted out is tricky. I’ll stick with the 102 for the next month then maybe retry the Edge 800 when I’m not having to stay up so late do testing. The info in the video was very useful as I hadn’t really thought the increased weight would be a big issue, but given the equations and the stiction I think my mount has I’ll have to look into improving things to image at longer focal lengths. Many thanks for the video. Clear skies.
Hi John. I get pretty much the same guiding performance regardless of scope weight. Before you take everything apart, you might look at 1:35 in this video: th-cam.com/video/ZpYZY_W5ur0/w-d-xo.html and see if you mount is constructed the same way. These mods to RA and DEC really do free up those axes. Good luck! There's nothing fun about using a high-magnification scope.
HI James. One of my Discord friends pointed me towards this video after seeing my guiding problems (elongated stars and choppy graphic). After a bit of pondering I decided to get a 3rd 11Lbs counterweight for my EQ6-R mount and see if I could improve performance. My OTA with guiding scope on top is 33Lbs all included. Distance to center of weights is 13" (now with 3 x11Lbs) and I estimated approx 14.5" to center of gravity up to the OTA. All this looks promising and my guiding really improved to a more calm graphic and with RMS between low 0.4 and low 0.7 - mostly in the low 0.5. However, I am still having elongated stars. They are more like short trails. My equipment is an 8" Newtonian -with CC at FL1035mm with an ST80 guide scope on top. Imaging camera is a ASI294MM-P (resolution 0.92"/pixel) and the guiding camera is an ASI120MC-S (resolution 1.92"/pixel). Ratio between guide and main scope is 1:2.1. Some colleagues tell me to get an OTA as the only solution but that is another $$$ and I just don't know if that really resolves the problem and as you say in your other Inertia related video, what do you do when no star is available to guide? Well, then at least I would not have a problem with elongated stars :) I am looking forward to hopefully getting some inputs from you. Always enjoying your videos. Cheers and thank you
Hey Georg! Welcome aboard. Actually, I'm very surprised that an additional counterweight would have such a positive effect. I wonder if something else didn't change in the process? Adding a counterweight will lead you to push the counterweights higher up the bar to achieve balance and that will reduce the mass moment of inertia, which is a good thing. But I wouldn't think it would be THAT good. If you have time and haven't already seen my older video (appologies for the poor sound), th-cam.com/video/8hMEgwQ3GnE/w-d-xo.html give it a watch. That's the video that convinced me to get the OAG. As you say, it's more $$$. But that will have a huge effect on your setup: (1) significant reduction on moment of inertia and (2) better image scale for guiding. Finding stars is an issue with an OAG and long focal length, but I find pre-planning with Stellarium has solved that for me (I also have videos for that process). Obviously, if you're getting good guiding consistently now, then maybe you don't need to pull the trigger on the OAG just yet. Your numbers sound good. So why the trailing stars?? A couple of things to consider: (1) if you're using really long exposures, then it may be image rotation from not-so-good polar alignment (2) If long exposures, it could be the dreaded "flexure" where the guide scope shifts/sags and the star moves in its field of view causing streaks in the image - an OAG will resolve this (3) Could be mirror slip/shift in the OTA if your scope has a moveable mirror (I don't think a Newt does) (4) There will be a tendency to have elongated stars because mechanical guiding error in RA is worse than in DEC, so more RMS error in RA causes stars to be more stretched along the RA versus the DEC axis. If you want, go to my email on my home page and send me the PHD2 guidelogs for a case before you got the new counterweight and a good guiding example after the counterweight. Also include a subframe or two that show the star trailing. Sorry for the long email.
@@Aero19612 Thanks James for responding. I tried to find your email but couldn't. I would definitely share my logs with you. With regards to the old video about adding counterweight, I saw it. I had to use the Atlas II extension bar and my counterweights were both down on the second one. So adding the 3rd did make a lot of sense. Looking forward to hearing from you again. Georg
James, there are a couple of videos showing how to loosen up the RA and Dec axes rotation so they are not so stiff and therefore help with better balancing of the OTA.. I would love to see your analysis and outcome due to my EQR6 being really stiff even though I am getting about the same RMS as you are but better RMS would be, well, better : )
Thanks for watching! I have watched those videos and have made the adjustments as I discuss here: th-cam.com/video/ZpYZY_W5ur0/w-d-xo.html They certainly make it easy to balance in DEC and RA now. The guiding may be a little better, but not a whole lot. Still, I think they are good adjustments to make.
Two other things to consider, if you are not already. 1. Check in PHD2 guiding the Fourier transform of you RA with the PHD log viewer or just do it yourself in python. First it is interesting to see the main periodes of your mount i.e. the main wurm gear period of 479sec but you also to see smaller freq. spikes i.e periods
Yep. I often do a Fourier analysis on guiding performance. It's a good approach. Yes, I have used PPEC. I don't see much difference in guiding performance with/without PPEC. PHD2 does a good job keeping up with the long period worm gear. Moving the counterweights up will reduce the MoI, but not by that much (see link below for video I did for the CGEM). Since all three payloads result in about the same guiding performance, playing with counterweight position won't do anything. CGEM counterweight video: th-cam.com/video/8hMEgwQ3GnE/w-d-xo.html
Wonderful informative Post James, you kept mentioning EQ6-R to achieve the 0.3 arcsec performance, although the results coming from the EQ6-RH, the decoded one, the question is: are you referring to this excellent performance to the "H decoder" version? or just the EQ6-R one? if it's the EQ6-RH one, does the decoder is responsible for this differnece?
Hi Ahmed. I talk mostly about my EQ6-R - better than 0.56 arc-sec 80% of the time. At the end I show the performance of the EQ8-RH that a friend of mine has. So the 0.32 arc-sec results come from the dual-encoder version. I'm not sure how much the encoders are responsible for the great performance. Thanks for watching.
Just found your channel and like it very much. Much respect for your science-based content, so I feel you would give a good and truthful answer to the following question. Do you think the Skywatcher EQ6-R Pro can handle and do well with a Celestron C11 OTA which is 7.5 lbs heavier than your 9.25 inch Celestron OTA, even for imaging? Thanks so much for your time and expert advice.
Hi Anthony and welcome. Well, I don't have a C11, of course. I have seen comments from others who are using a C11 on the EQ6-R quite successfully. So, I think it is possible to get very good results. I think you'll want to give yourself every possible advantage though. You might consider an Off-axis guider, if you don't have one. This has three big advantages: (1) it will significantly reduce the mass moment of inertia that the RA motor has to deal with, (2) it will provide a more appropriate image scale for your guide camera (an ASI174mini with its big sensor area would be nice), and (3) it will prevent guide scope image shift (aka flexure) for long exposures and the resulting star trailing that can occur as a result. The Celestron OAG is nice in that you can independently orient the guide camera and the imaging camera fields of view. By all means, get additional opinions on using the C11 with the EQ6-R. I have no indication that I'm up against a weight limit with my scopes. Good Luck!
Great! I really like the EQ6-R. I’ve been using mine for a little over a year and plan to put out a 1-year review video. Unless you’re imaging with a C14 or maybe a C11, I still totally recommend it. Good luck!
@@Brians_Astro-Adventures Absolutely. The weight of those scopes isn't the issue. The EQ6 will be fine. I was referring to the guiding error and its effect on high focal length scopes. The RASA is about 400mm focal length, right? So that's definitely not a problem. I get pretty good guiding with my EQ6, but I do notice effects at 2310 mm. The EQ8 I mention in the video is an improvement, but at a cost. Thanks for watching!
Mean RMS is great, but standard deviation is as important. Problem with Skywatcher, Celestron and some other mounts is high SD. Mean 0.45” RMS is terrific and as good as Paramount mounts. But SD is higher as much as triple.
Your guiding on m1 is strangely very similar to mine. I shot M1 early in the evening and then moved to m82. My guiding was around .8RMS on M1 and went down to .5 RMS on M82. No rooftop for me. My suspicion was that the mount wasnt Handling that particular RA and DEC coordinates and slowing to another angle fixed the issue
Interesting. I'm just "theorizing" about the effect of the roof line. If anything, I expect better guiding near M1 as there are more stars to choose from. With M81, I have 1 or 2 stars in my OAG field of view. Problem could very well be location on sky (i.e., location on worm gear). But then I'd be surprised we would see the same thing. The curse of small sample size when trouble shooting... Thanks for watching!
These mounts work great until about a year. Just hyper tuned mine myself and guiding is better then new. Also use high frequency guiding in phd with .5-1 second exposures. Predictive pec on ra and resist switch on Dec. now back to .6-.4. The mount was a mess inside.
Interesting. I fully expect to rebuild it at some point. Hopefully, when it's out of warranty. Do you leave your mount outside 260 days/year? Thanks for watching!
@@Aero19612 it lives on the garage. Just roll it out. Usually have an rc8 on it these days. So as an fyi I followed joe and astrobloke videos. I replaced all of the large bearings and roller bearings and cleaned it all up. I skipped the worm gears and just cleaned those up. So if things start to go south you know where to look. It’s actually easy and skipping those worn carriers saved me a lot of time and frustration. I didn’t see a benefit to swapping those little bearings out for the work that would have been involved. A gamble that paid off.
That's disheartening to hear. Mine did not work very well from the beginning.. And if it will go worse as time goes on it will straight up be quite bad :(
James, I would be interested your thoughts on encoders. The EQ8-RH uses the Renshaw encoder that has 11.7 million tic marks. Do you think that many tics is necessary or did they just adapt an industrial encoder?
I don't know much about the EQ8-RH. 11.7x10^6 tic marks sounds large, but when you break it down, it's a good scale for AP. Angular measure between tics = 360 deg/11.7x10^6 = 0.11 arc-sec. The EQR-8 is intended for large/heavy scopes. A C14 SCT with 2.4 um pixel imaging sensor has an imaging scale of 0.14 arc-sec. So, the EQ8-RH can control pointing within 1 pixel for a C14 with small pixels. Now for a reality check: There's no way typical seeing we suffer with will allow you take advantage of that precision.
Have a look at DarkFrame optics - he’s been super tuning mounts for years and the latest “Ultra” build for an eq6 r is about 0.16 arc secs over 4hrs I believe. Sadly my mount is quite old now (black EQ6, remember them?!) So mine isn’t that good but Dave did improve it a lot for me. Fair warning he’s got a sales patter but it’s a good service
He's in the UK, right? We have DeepSpaceProducts here in the US. I'm sure I'll need to make adjustments some time after the warranty runs out. I may just do it myself. Maybe practice on my CGEM (which was hypertuned by DSP - not much improvement on guiding, but can't put lipstick on a pig). Thanks for watching, Peter!
@@Aero19612 yes he’s UK but I understand he does a lot with the US. I’m not trying to over sell him really, but he runs out astro club so I know a little of what he does. Anyway, love the videos and your engineering approach to our hobby, it always reminds me to think more scientifically about the things I see when imaging, whether successfully or not.
@@pmasters2 I understand. Thanks for the suggestion. Actually, I believe I saw one of his videos and, if I recall, he was saying the EQ6 was a really good mount. I thought it was a well-done video and, if he were local, might have him at the top of the list should I elect to have a 3rd party tune up the mount.
Yes. That will reduce the moment of inertia that the RA torque motor has to overcome. However, the benefit may be so small that you don't see a difference in your guiding. In other words, don't go buy another counterweight just to have more weight. See this (old) video if you're interested: th-cam.com/video/8hMEgwQ3GnE/w-d-xo.html
i am wondering if the same payload but use more counter wight to balance it . i mean let the counter weight more close to the center .is that possible to make guiding better?
Hi Charles. Probably not. As I show in the video, the guiding is about the same regardless of the weight (mass moment of inertia). The MoI for the GT81 is much much smaller than the C925 MoI. If you're interested, take a look at this video I did some time back: th-cam.com/video/8hMEgwQ3GnE/w-d-xo.html
I'd like to see a similar analysis on half a dozen unmolested examples of the mount particularly as they age. Problem is there is no shortage of "improved" specimens where the owner has followed poor advice on DIY "hypertunes" found on here. I cringe every time someone spends $2-300 changing perfectly good bearings because one or both axes bind with the clutches dis-engaged. 90% of the time the binding is drag between the main housing and the clutch drum and has no effect on guiding performance only when static balancing to a very fine balance does this drag become problematic. Eq8R vs EQ8Rh with Renishaw encoders now please. I believe Dillon has the Rh model 😉
Agree. It would be "fun" as a rainy-day project to crowd source guidelogs from various mounts to see how they operate and then plot the arc-sec RMS VS cost. How much do you wan to pay $/arc-sec? The example of the EQ8 is an EQ8-RH. But, yes, comparing an R to and RH would be interesting.
Hello James, thanks for those numbers who are so precious to have a real-life understanding of the mounts performances.
Thanks for watching, Bernard!
As always a very interresting video. Thanks for your work to explain with very clear graphs and sheets common problems of astrophotographers.
Thanks for watching, Olivier!
Great informative video. A real step above the rest. Thank you
Thanks for watching, Danie!
Excellent analysis. Many thanks.
Thanks! And thanks for watching!
This is very helpful. Thank you so much!
Great! I’m glad you found it useful. Thanks for watching!
Really appreciate your analysis. I did a belt mod on my Atlas EQ-G and could tell I was getting better results, but not like this! Thanks!
Thanks for watching! Coming from a CGEM, I'm quite pleased with the EQ6-R. Seems to be a good mount for the money.
This is fantastic James! Seems pretty similar to the results I get from my Z81 and EdgeHD 8 on the EQ6-R. I do need to adjust my worm carriers every now and then depending on the extreme temperature differences. June - August, we have 90F+ temps and in December-February we can see -10F temps. The temps seem to really effect the worm drives.
I'll have to keep track of these numbers going forward as we enter the Summer months. I suspect I'll be referring to your and Astrobloke's tune-up videos once my warranty expires.
Very interesting to see the statistical information from PHD2 analysed and nicely presented in easy to understand graph form. I think you can feel pretty happy with below 0.53 total RMS error - the EQ-R can wait a bit longer :)
Haha. The $10,000 price tag will definitely make me wait. Plus, I'd have to lug that beast in and out since I don't have a permanent setup. How much are those 0.2 arc-sec RMS worth? The open question is whether those 0.2 arc-sec actually lead to smaller FWHM - you can't beat seeing! Thanks for watching, Logan!
@@Aero19612 yes indeed. In good seeing my CEM120 can be down at 0.28 but in bad up to 0.8 so maybe better to invest in a property on top of a mountain 🤣
Very in-depth as usual. I've had my EQ6R-Pro for about 2 years which replaced an AVX. I have two Explore Scientific telescopes - ED80 FCD100 plus Orion 50mm guidescope & ED127 FCD100 plus ZWO OAC. Neither is pushing this mount's weight limit and the guiding for both scopes is fairly equal even through the stars in the OAG are elongated and horrible. Normally, I expect a combined RMS ~0.5" unless seeing is bad or setup is poor. Weight balance issues can easily double the error - nights with great guiding prior to meridian flip followed by bad guiding after or vice versa. I've found like many others have suggested in the forums, my inconsistent guiding performance can be improved with a slight imbalance to reduce backlash. I've also heard not being exactly polar aligned also helps but I've found my best DEC performance with nearly perfect PA. I've had successful operation down to -34 C (-30 F). All in all, it's a great mount for the price!
Totally agree, Greg. This is a very good mount for the money. If you want to shell out the additional $8,000 for an EQ8-R, for the additional 0.2 arc-sec, that's cool. But I'm pretty pleased with the performance, especially coming from the CGEM. Thanks for watching!
Great analysis. I use this mount with a C8, w/o going through the numbers your results "feel" about what I observe (N.I.N.A + PHD2 + GSS with alternete PEC algorithm). However for my EQ6R-Pro I had to do the worm gear adjustment shown in Cuiv's and Astrobloke's videos to tighten up the backlash. Made a HUGE difference. The observation of roof-top affecting guiding is also very interesting, In my case I've often observed guiding to be terrible until sometime after the meridian flip.. Earlier in the night I'm often pointed across a roof, perhaps I've the same thing. Or maybe one side of the pier is better than the other? Great video!
Hey Bruce. Thanks for the feedback. Things may loosen over time and then I'll have to do the adjustments you're talking about. As you say, the location on the worm gear has an effect as well. Thanks for watching!
Great video James!!!
Now I'm jealous of your EQ8!
@@Aero19612 lol, it's a great mount! However, about 6 weeks ago, I put my edge11 on the EQ6 to give it a try even though it's at or above the weight limit, and with good balance I was getting 0.4rms using the OAG. Eq6 is a great mount, better than my old cgx-l honestly. I still haven't gotten around to making any videos yet but maybe I should regarding some super tuning I have done to my eq6. Do you still have your chem or did you sell it?
No. Still have the CGEM. Toying with the idea of using it as a second rig for a short focal length scope (e.g., Redcat) that can tolerate “poor” guiding. Yeah, make an EQ6 tuning video. There several out there, but a different approach and suggestions are valuable.
Great work.
I have just tweaked the BL on my EQ6R. Funny enough I ended up giving it a bit more slack. I connected a amp-meter to it and I could see at one side it was drawing more. From 2 nights of testing it seems like I got rid of some spikes and my RMS went 0,2 down.
For me it seems like a lot of EQ6Rs are very stiff from the factory. First thing I "tweaked" was to loosen the axis and tighten them again, but not factory tight, that made it easier to balance (smooooth). Second is the thing with the amp-meter. A bit more technical, but seemed to solve a problem that have annoyed me a long time.
Yes, the RA axis is a bit stiff on mine. I will try to make adjustments to loosen things up a bit to make balancing more accurate. Will have a look at the amp meter. Thanks for watching!
You have to be both an engineer and a statistician for this hobby ! Nice video. I’m working on dialing in my CEM70 right now and this is very helpful
Haha. Or just ignore all this stuff and take good pictures anyway! Thanks for watching, Nick!
How are you getting on with that CEM70? I'm really contemplating one...
@@fredmercury1314 Overall I really like it. Great payload for the size. Solid. What I don't like 1. The bolts are really hard to access to fix it to the tri-pier so if you are setting up each night, it's really frustrating. Some people tap holes in the pier top plate. 2. I still have some guiding spikes in RA and Dec. OVerall RMS is in the 0.4-0.6 which is great, but sometimes spikes up to 2.6 or so in each axis very briefly and I don't know why. Through the mount cabling is really really nice.
Interesting as always. I have an AZEQ6GT and I’ve been pleased with it. I now have a permanent setup on a pier. My total RMS for my 65 and 102 refractors is excellent. Last night with my 192 it was less than 0.3! I think it was very good seeing, but it’s always good. When I mount my Edge 800 it all goes to pieces. My PA is spot on and I use a QSI660 with built in OAG plus the Celestron 0.7x reducer. At 1400mm I get bad star trails even on short exposures of around 10 seconds and guiding just can’t deal with the corrections needed. I run the rig from a battery so I’m guessing it’s either not enough power or I need to strip the mount down and re grease the bearings etc. I know the mount is stiff in RA because getting balance sorted out is tricky. I’ll stick with the 102 for the next month then maybe retry the Edge 800 when I’m not having to stay up so late do testing. The info in the video was very useful as I hadn’t really thought the increased weight would be a big issue, but given the equations and the stiction I think my mount has I’ll have to look into improving things to image at longer focal lengths. Many thanks for the video. Clear skies.
Hi John. I get pretty much the same guiding performance regardless of scope weight. Before you take everything apart, you might look at 1:35 in this video:
th-cam.com/video/ZpYZY_W5ur0/w-d-xo.html
and see if you mount is constructed the same way. These mods to RA and DEC really do free up those axes. Good luck! There's nothing fun about using a high-magnification scope.
A good video and nice bit of maths, thank you
Thanks for watching!
HI James. One of my Discord friends pointed me towards this video after seeing my guiding problems (elongated stars and choppy graphic). After a bit of pondering I decided to get a 3rd 11Lbs counterweight for my EQ6-R mount and see if I could improve performance. My OTA with guiding scope on top is 33Lbs all included. Distance to center of weights is 13" (now with 3 x11Lbs) and I estimated approx 14.5" to center of gravity up to the OTA. All this looks promising and my guiding really improved to a more calm graphic and with RMS between low 0.4 and low 0.7 - mostly in the low 0.5. However, I am still having elongated stars. They are more like short trails. My equipment is an 8" Newtonian -with CC at FL1035mm with an ST80 guide scope on top. Imaging camera is a ASI294MM-P (resolution 0.92"/pixel) and the guiding camera is an ASI120MC-S (resolution 1.92"/pixel). Ratio between guide and main scope is 1:2.1. Some colleagues tell me to get an OTA as the only solution but that is another $$$ and I just don't know if that really resolves the problem and as you say in your other Inertia related video, what do you do when no star is available to guide? Well, then at least I would not have a problem with elongated stars :)
I am looking forward to hopefully getting some inputs from you. Always enjoying your videos. Cheers and thank you
Hey Georg! Welcome aboard. Actually, I'm very surprised that an additional counterweight would have such a positive effect. I wonder if something else didn't change in the process? Adding a counterweight will lead you to push the counterweights higher up the bar to achieve balance and that will reduce the mass moment of inertia, which is a good thing. But I wouldn't think it would be THAT good. If you have time and haven't already seen my older video (appologies for the poor sound),
th-cam.com/video/8hMEgwQ3GnE/w-d-xo.html
give it a watch. That's the video that convinced me to get the OAG. As you say, it's more $$$. But that will have a huge effect on your setup: (1) significant reduction on moment of inertia and (2) better image scale for guiding. Finding stars is an issue with an OAG and long focal length, but I find pre-planning with Stellarium has solved that for me (I also have videos for that process).
Obviously, if you're getting good guiding consistently now, then maybe you don't need to pull the trigger on the OAG just yet. Your numbers sound good. So why the trailing stars?? A couple of things to consider:
(1) if you're using really long exposures, then it may be image rotation from not-so-good polar alignment
(2) If long exposures, it could be the dreaded "flexure" where the guide scope shifts/sags and the star moves in its field of view causing streaks in the image - an OAG will resolve this
(3) Could be mirror slip/shift in the OTA if your scope has a moveable mirror (I don't think a Newt does)
(4) There will be a tendency to have elongated stars because mechanical guiding error in RA is worse than in DEC, so more RMS error in RA causes stars to be more stretched along the RA versus the DEC axis.
If you want, go to my email on my home page and send me the PHD2 guidelogs for a case before you got the new counterweight and a good guiding example after the counterweight. Also include a subframe or two that show the star trailing. Sorry for the long email.
@@Aero19612
Thanks James for responding. I tried to find your email but couldn't. I would definitely share my logs with you. With regards to the old video about adding counterweight, I saw it. I had to use the Atlas II extension bar and my counterweights were both down on the second one. So adding the 3rd did make a lot of sense. Looking forward to hearing from you again. Georg
James, there are a couple of videos showing how to loosen up the RA and Dec axes rotation so they are not so stiff and therefore help with better balancing of the OTA.. I would love to see your analysis and outcome due to my EQR6 being really stiff even though I am getting about the same RMS as you are but better RMS would be, well, better : )
Thanks for watching! I have watched those videos and have made the adjustments as I discuss here: th-cam.com/video/ZpYZY_W5ur0/w-d-xo.html
They certainly make it easy to balance in DEC and RA now. The guiding may be a little better, but not a whole lot. Still, I think they are good adjustments to make.
Two other things to consider, if you are not already.
1. Check in PHD2 guiding the Fourier transform of you RA with the PHD log viewer or just do it yourself in python. First it is interesting to see the main periodes of your mount i.e. the main wurm gear period of 479sec but you also to see smaller freq. spikes i.e periods
Yep. I often do a Fourier analysis on guiding performance. It's a good approach. Yes, I have used PPEC. I don't see much difference in guiding performance with/without PPEC. PHD2 does a good job keeping up with the long period worm gear.
Moving the counterweights up will reduce the MoI, but not by that much (see link below for video I did for the CGEM). Since all three payloads result in about the same guiding performance, playing with counterweight position won't do anything.
CGEM counterweight video:
th-cam.com/video/8hMEgwQ3GnE/w-d-xo.html
Wonderful informative Post James, you kept mentioning EQ6-R to achieve the 0.3 arcsec performance, although the results coming from the EQ6-RH, the decoded one, the question is: are you referring to this excellent performance to the "H decoder" version? or just the EQ6-R one? if it's the EQ6-RH one, does the decoder is responsible for this differnece?
Hi Ahmed. I talk mostly about my EQ6-R - better than 0.56 arc-sec 80% of the time. At the end I show the performance of the EQ8-RH that a friend of mine has. So the 0.32 arc-sec results come from the dual-encoder version. I'm not sure how much the encoders are responsible for the great performance. Thanks for watching.
Just found your channel and like it very much. Much respect for your science-based content, so I feel you would give a good and truthful answer to the following question. Do you think the Skywatcher EQ6-R Pro can handle and do well with a Celestron C11 OTA which is 7.5 lbs heavier than your 9.25 inch Celestron OTA, even for imaging? Thanks so much for your time and expert advice.
Hi Anthony and welcome. Well, I don't have a C11, of course. I have seen comments from others who are using a C11 on the EQ6-R quite successfully. So, I think it is possible to get very good results. I think you'll want to give yourself every possible advantage though. You might consider an Off-axis guider, if you don't have one. This has three big advantages: (1) it will significantly reduce the mass moment of inertia that the RA motor has to deal with, (2) it will provide a more appropriate image scale for your guide camera (an ASI174mini with its big sensor area would be nice), and (3) it will prevent guide scope image shift (aka flexure) for long exposures and the resulting star trailing that can occur as a result. The Celestron OAG is nice in that you can independently orient the guide camera and the imaging camera fields of view. By all means, get additional opinions on using the C11 with the EQ6-R. I have no indication that I'm up against a weight limit with my scopes. Good Luck!
@@Aero19612 James, thanks so much for your detailed and quick response. Love your channel. All the best.
Thinking of getting a Eq6r pro too… I think you sold me. Lol
I’ll break in visually before photos
Thanks for the heads up. 👍
Great! I really like the EQ6-R. I’ve been using mine for a little over a year and plan to put out a 1-year review video. Unless you’re imaging with a C14 or maybe a C11, I still totally recommend it. Good luck!
@@Aero19612
C11 oh no I was and a rasa 8
I’ve seen it done successfully…
I know it’s not recommended but it does work. Just saying.
@@Brians_Astro-Adventures Absolutely. The weight of those scopes isn't the issue. The EQ6 will be fine. I was referring to the guiding error and its effect on high focal length scopes. The RASA is about 400mm focal length, right? So that's definitely not a problem. I get pretty good guiding with my EQ6, but I do notice effects at 2310 mm. The EQ8 I mention in the video is an improvement, but at a cost. Thanks for watching!
Mean RMS is great, but standard deviation is as important. Problem with Skywatcher, Celestron and some other mounts is high SD. Mean 0.45” RMS is terrific and as good as Paramount mounts. But SD is higher as much as triple.
Great!
Well, "good enough", anyway. Thanks for watching!
Your guiding on m1 is strangely very similar to mine. I shot M1 early in the evening and then moved to m82. My guiding was around .8RMS on M1 and went down to .5 RMS on M82. No rooftop for me. My suspicion was that the mount wasnt Handling that particular RA and DEC coordinates and slowing to another angle fixed the issue
Interesting. I'm just "theorizing" about the effect of the roof line. If anything, I expect better guiding near M1 as there are more stars to choose from. With M81, I have 1 or 2 stars in my OAG field of view. Problem could very well be location on sky (i.e., location on worm gear). But then I'd be surprised we would see the same thing. The curse of small sample size when trouble shooting... Thanks for watching!
These mounts work great until about a year. Just hyper tuned mine myself and guiding is better then new. Also use high frequency guiding in phd with .5-1 second exposures. Predictive pec on ra and resist switch on Dec. now back to .6-.4. The mount was a mess inside.
Interesting. I fully expect to rebuild it at some point. Hopefully, when it's out of warranty. Do you leave your mount outside 260 days/year? Thanks for watching!
@@Aero19612 it lives on the garage. Just roll it out. Usually have an rc8 on it these days. So as an fyi I followed joe and astrobloke videos. I replaced all of the large bearings and roller bearings and cleaned it all up. I skipped the worm gears and just cleaned those up. So if things start to go south you know where to look. It’s actually easy and skipping those worn carriers saved me a lot of time and frustration. I didn’t see a benefit to swapping those little bearings out for the work that would have been involved. A gamble that paid off.
That's disheartening to hear. Mine did not work very well from the beginning.. And if it will go worse as time goes on it will straight up be quite bad :(
James, I would be interested your thoughts on encoders. The EQ8-RH uses the Renshaw encoder that has 11.7 million tic marks. Do you think that many tics is necessary or did they just adapt an industrial encoder?
I don't know much about the EQ8-RH. 11.7x10^6 tic marks sounds large, but when you break it down, it's a good scale for AP. Angular measure between tics = 360 deg/11.7x10^6 = 0.11 arc-sec. The EQR-8 is intended for large/heavy scopes. A C14 SCT with 2.4 um pixel imaging sensor has an imaging scale of 0.14 arc-sec. So, the EQ8-RH can control pointing within 1 pixel for a C14 with small pixels. Now for a reality check: There's no way typical seeing we suffer with will allow you take advantage of that precision.
@@Aero19612 Thanks James, I knew you would be able to put it in perspective1
Have a look at DarkFrame optics - he’s been super tuning mounts for years and the latest “Ultra” build for an eq6 r is about 0.16 arc secs over 4hrs I believe. Sadly my mount is quite old now (black EQ6, remember them?!) So mine isn’t that good but Dave did improve it a lot for me. Fair warning he’s got a sales patter but it’s a good service
He's in the UK, right? We have DeepSpaceProducts here in the US. I'm sure I'll need to make adjustments some time after the warranty runs out. I may just do it myself. Maybe practice on my CGEM (which was hypertuned by DSP - not much improvement on guiding, but can't put lipstick on a pig). Thanks for watching, Peter!
@@Aero19612 yes he’s UK but I understand he does a lot with the US. I’m not trying to over sell him really, but he runs out astro club so I know a little of what he does. Anyway, love the videos and your engineering approach to our hobby, it always reminds me to think more scientifically about the things I see when imaging, whether successfully or not.
@@pmasters2 I understand. Thanks for the suggestion. Actually, I believe I saw one of his videos and, if I recall, he was saying the EQ6 was a really good mount. I thought it was a well-done video and, if he were local, might have him at the top of the list should I elect to have a 3rd party tune up the mount.
So you are saying i should use heavier counter weights rather than moving them further away from center on the counter balance arm?
Yes. That will reduce the moment of inertia that the RA torque motor has to overcome. However, the benefit may be so small that you don't see a difference in your guiding. In other words, don't go buy another counterweight just to have more weight. See this (old) video if you're interested:
th-cam.com/video/8hMEgwQ3GnE/w-d-xo.html
i am wondering if the same payload but use more counter wight to balance it . i mean let the counter weight more close to the center .is that possible to make guiding better?
James has a detailed video from quite some time ago covering this exact question.
Hi Charles. Probably not. As I show in the video, the guiding is about the same regardless of the weight (mass moment of inertia). The MoI for the GT81 is much much smaller than the C925 MoI. If you're interested, take a look at this video I did some time back:
th-cam.com/video/8hMEgwQ3GnE/w-d-xo.html
I'd like to see a similar analysis on half a dozen unmolested examples of the mount particularly as they age. Problem is there is no shortage of "improved" specimens where the owner has followed poor advice on DIY "hypertunes" found on here. I cringe every time someone spends $2-300 changing perfectly good bearings because one or both axes bind with the clutches dis-engaged. 90% of the time the binding is drag between the main housing and the clutch drum and has no effect on guiding performance only when static balancing to a very fine balance does this drag become problematic. Eq8R vs EQ8Rh with Renishaw encoders now please. I believe Dillon has the Rh model 😉
Agree. It would be "fun" as a rainy-day project to crowd source guidelogs from various mounts to see how they operate and then plot the arc-sec RMS VS cost. How much do you wan to pay $/arc-sec? The example of the EQ8 is an EQ8-RH. But, yes, comparing an R to and RH would be interesting.