KevS Posted January 29, 2021 Share Posted January 29, 2021 M81 evenings of 25th and 26th January 2021. 173 x 180s, ISO800 + Darks/Flats/Bias, Canon 600d (Non-Mod), 152 f5.9 TS, IR/UV cut off. Stacked in DSS and manipulated in GIMP. Bit rough and ready but first image for months. 6 Quote Link to comment Share on other sites More sharing options...
Gina Posted January 29, 2021 Share Posted January 29, 2021 Well done Kev! ? Quote Link to comment Share on other sites More sharing options...
Padraic M Posted January 29, 2021 Share Posted January 29, 2021 Nice one. Lucky you with clear skies! Quote Link to comment Share on other sites More sharing options...
peter shah Posted January 29, 2021 Share Posted January 29, 2021 Nicely captured Kev...particularly like the star colour Quote Link to comment Share on other sites More sharing options...
Bob-c Posted January 29, 2021 Share Posted January 29, 2021 Nice capture Kev.Bob. Quote Link to comment Share on other sites More sharing options...
AstronomyUkraine Posted January 29, 2021 Share Posted January 29, 2021 Posted by: @KevS M81 evenings of 25th and 26th January 2021. 173 x 180s, ISO800 + Darks/Flats/Bias, Canon 600d (Non-Mod), 152 f5.9 TS, IR/UV cut off. Stacked in DSS and manipulated in GIMP. Bit rough and ready but first image for months. Looking great. You are the envy of everyone on here, nobody else is doing much at all.Brian Quote Link to comment Share on other sites More sharing options...
MarkAR Posted February 2, 2021 Share Posted February 2, 2021 Nice one Kev, all you need now is to sort out the walking noise. Quote Link to comment Share on other sites More sharing options...
KevS Posted February 2, 2021 Author Share Posted February 2, 2021 Posted by: @MarkAR Nice one Kev, all you need now is to sort out the walking noise.Thanks Mark, I was dithering but obviously not enough. The new PHD2 2 star guiding is playing havoc with the mount's auxiliary "built in dither" ? May have to increase the dither used via APT. Quote Link to comment Share on other sites More sharing options...
MarkAR Posted February 4, 2021 Share Posted February 4, 2021 (edited) On 2/2/2021 at 12:39 PM, KevS said: mount's auxiliary "built in dither" I take it you can't turn that off. Edited February 4, 2021 by MarkAR Quote Link to comment Share on other sites More sharing options...
KevS Posted February 4, 2021 Author Share Posted February 4, 2021 I rebuilt the mount some time ago, replacing the bearings and the snot that passes as grease from Skywatcher. I get 0.2"-0.3" RMS as a result. Replacing the bearings also improved the orthoganality of the mount no end. I used to get better results with regarding to "walking noise" previous to the rebuild due to the inbuilt errors in the drive system. Improving the mechanicals on the mount has certainly improved tracking, but has brought out the previously mentioned walking noise. I am still subject to a certain amount of field rotation as I set up from scratch and I can not normally get closer than about 4-5 arc minutes. If we ever get a run of clear nights again I will have to experiment with the dither settings and see if I can dial it out. 1 Quote Link to comment Share on other sites More sharing options...
Stub Mandrel Posted February 6, 2021 Share Posted February 6, 2021 On 2/4/2021 at 2:20 PM, KevS said: I rebuilt the mount some time ago, replacing the bearings and the snot that passes as grease from Skywatcher. I get 0.2"-0.3" RMS as a result. Replacing the bearings also improved the orthoganality of the mount no end. I used to get better results with regarding to "walking noise" previous to the rebuild due to the inbuilt errors in the drive system. Improving the mechanicals on the mount has certainly improved tracking, but has brought out the previously mentioned walking noise. I am still subject to a certain amount of field rotation as I set up from scratch and I can not normally get closer than about 4-5 arc minutes. If we ever get a run of clear nights again I will have to experiment with the dither settings and see if I can dial it out. What grease did you use? I used teflon grease on an EQ3 with success but clearly whatever you used has worked! Quote Link to comment Share on other sites More sharing options...
KevS Posted February 7, 2021 Author Share Posted February 7, 2021 I used PTFE/Moly grease that I use for my bike wheels, the bearings I replaced were the most important factor, I used "P4" class SKF class bearings. (Taper needle bearings) I wanted to use P5's ( traceable) but they would have cost more than the mount. Fortunately the P4 class sets were readily available "free" from contacts within industry. There appeared to be some spalling on the mount castings due to possible movement/vibration of the original outer races, as a consequence "641" bearing lock was used to assist location after the inner castings were "popped". End float/preload was achieved using a digital DTI allowing for the stretch in both Dec and Ra shafts. The following may be of use. Principles of bearing selection and application | SKF | SKF K 1 Quote Link to comment Share on other sites More sharing options...
Stub Mandrel Posted February 7, 2021 Share Posted February 7, 2021 1 hour ago, KevS said: I used PTFE/Moly grease that I use for my bike wheels Ah, I used Finish Line PTFE bike grease - great minds think alike! Looks like a sound approach, I am lucky in knowing a bearing importer. 🙂 Quote Link to comment Share on other sites More sharing options...
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