malc-c

Here's the guid assist results. The mount was running PEC, which may be the reason why the Polar align went from 0.8 through 0.0 and back up to 0.6? But I've reduced the backlash from 6305 to 701 which is the main thing. As things are going so well I didn't apply the recommendations. I've now moved to a target (09:33 RA, +21:24 DEC) and the guiding is just as smooth. Running off 20x 4 minute subs and the stars are nice and round

Guys, I followed the same process at other nights... Slewed to Procyon, released clutches and centred the star in the finder and locked them into place Set DEC to zero degrees (or as close as I could to within 00:00:03 Set RA to around 9 hrs Opened PHD2 and created a new profile Set the exposure to 1.5s Auto selected star Calibrated - received a warning that RA was 104% of DEC rather than 100% - closed and let it begin guiding Fell of my observatory seat ! (see attached) The mount is running with the PEC file generated through EQMODs PECPREP I've attached a couple of screen captures whilst its gathering data, and naturally I'll post up the log files later. I'll run the guide assistance later, but I really want to get an hour or so's data

Well I've just spent the past couple of hours rebalancing the mount, re-routing cables so (hopefully) the don't impact the results, and adjusting the worm gear tension / mesh. It will either improve things or make them worse.. All being well if it remains clear and the high level thin cloud goes away I'll give it another test tonight.

Thanks for the reassurance. The thing I don't get is that having found there was movement in the DEC axis (backlash or free play) I tigherned things up so the movement went away but didn't bind the axis. The RA wasn't touched, but the scope was rebalanced. Yet now we have E/W overshoot on the RA axis, and PHD2 is complaining about backlash after a calibration run, which it didn't do previously. Yet the actual guiding seems more precises looking at the target reticule and graph. I didn't take any images to see what the stars looked like so can't comment on that. The seeing was deteriorating, with a noticeable foggy glow around Venus, and the sky had a thickness about it, making it hard to see fainter stars. You would think in this current lockdown, with less cars on the roads, and most airlines grounding the planes that the atmosphere would be a lot more transparent and stable. I'll check for end float on the gears, but won't try and improve any other alignment. I may also look at the balance of the scope, maybe I missed something (lightbulb moment ! ) - One thing I did was to balance the scope with all the covers off. Maybe previously when balancing the RA axis it had the covers on and it the weight of the cover causing the CG / balance to be just slightly out, but just enough to induce the RA overshoot ?? - Nothing on the RA was touched today. The balance was DEC only with the CG checked (placing the mount with the weight bar horizontal, loosen the DEC clutch and place the OTA vertical. If it then wants to swing rotate the OTA until it balances and remains in any position around the DEC axis). Comparing the previous guide assist report with tonights, it's heading in the right direction, I've reduced the backlash error by over 4s

Or maybe just give up and let the thing gather dust over the next four years....or until I can be bothered. Here's tonights log file. I've closed up for the night as there is something on TV and I'm no longer in the mood. PHD2_GuideLog_2020-04-14_204516.txt

OK, things are not going well.... Managed to get better focus of the finder.... aligned the finder up with the main scope and the red dot finder so everything is pointing at the same thing. Set the DEC to 00.00 and RA to around 9/10 hrs and opened PHD2 - cleared previous calibration data and let it select the start. The good news is that on 1sec exposures the HFD is low so the effort to focus the finder seems to have paid off. But, no matter what I do I now get error messages stating there is a difference between the axises as a result of huge backlash errors - but the mount is now tight where as I found movement this afternoon. I've run the guide assistant (see attached) and accepted its findings - I've set it running with PPEC enabled in the settings (disabled the EQMOD option). I'm running a data run at the moment and will load the log files later, although with the constant stop starts whilst I tried getting the guide assistant to run (user error) its a bit of a mess ! Maybe the mount is just worn... ??

Nope ! There is no goto error in DEC. Originally I released the clutches on the mount, set it to park in the traditional home position with the weights down pointing at Polaris. Once parking was complete eyeballed the position as close as I could and locked the clutches. Picked Procyon as a target, slewed and it was close, just needing the RA clutch to be slackened off and the mount rotated slightly westwards. DEC was spot on. The star was synced in CDC, the scope parked, and the star reselected... it was bang on. Selected Pollox - slewed and bang on. I repeated this for around four other targets and they all appeared within the field of view of the d400, most fairly central. So the ratios and EQMOD settings would appear to be OK. One thing I have done today is (hopefully) sorted out the DEC freeplay/backlash. With the scope ballance checked again I noticed a very, very slight movement in the DEC axis when the clutch was locked off. When locked with the tube horizontally, pushing with the finger on the mirror cell, you could feel a slight bit of free play. It was almost impossible to visually see the movement, but you could feel it, so I spent an hour with the allen keys out adjusting the worm guides until the mount had no movement at all, but the gears still engaged and didn't bind or slip. The mount was then driven in all rotations on both axis to ensure there was no slipping, or stalling. I've now just got to find a means of being able to fine tune the guider focus and hopefully this nice clear blue sky will remain so I can test the results later.

At the time of developing the belt drive my experiments with commercially available pulleys resulted in the 4:1 ratio as being the best compromise for speed and torque. Smaller pulleys resulted in failure having enlarged the hole to fit the motor. Chris who developed EQAscom modified EQMOD to handle the 4:1 ratio (in fact he added additional 5:1 and more ratios as well) He did all the calculations and recompiled the application. Now whilst there were a lot of people using EQMod to control their scopes, the belt drive was not an option for those who used the hand controller, so this is were Dave stepped in. He owned a business that has CNC machines, so milled the motor pulley from one piece of material so as to maintain the default ratio without the motor pulley failing. With the PA as good as it is, my goto's have been very good. The HEQ5 was purchased second hand in 2011, but was stripped and serviced in 2012. I'll get the tool box out and have a look at tightening up the worm to see if that improves backlash. As mentioned, I've downloaded the latest versions of these applications. I could re-install older versions, but to be honest I personally doubt if that would make any difference. Let me revisit the scope balancing, finder focus and adjust the DEC worm and see if I get any better results.

Hi Michael, I have no idea on how the mount performed when geared as the changes were done in 2011 and I no longer have any log files. As mentioned the belt drive was effectively the first belt drive mod for the HEQ5 - it uses the same toothed pulleys for both RA and DEC. 60t on the axis and 15t on the motor. EQMOD set to 4:1 ratio as shown above. I could try and take up the backlash by adjusting the worm backlash adjustment on the mount. The idea will be to use PEC for guiding.

I managed to grab an hour or so in late twilight to do some testing. Started with a fresh profile, ran through the wizard let it select the defaults, none of the settings were manually tweaked, and let the applications take dark frames with the lens cap still on the camera. Removed lens caps and covers and set the scope up to zero declination and then rotated the scope in RA until the scope was pointing south and luckily the camera found a bright star. Due to it still being quite bright the exposure was as low as 100ms with the screen contrast as far right. With a 200mS exposure the star had FWHM values between 0.85 and 1.75 - seldom over 2. The star graph showed a sharp thin spike rather than fat based rounded image. I kicked off guiding (log entry 1) and it took around 10 steps in each direction and reported no errors. I didn't save the the result. The mount started guiding (log entry 2). I let it run for around 10 minutes. I then ran the guiding assistant (log entry 3), but wasn't sure if I had done things right, so stopped and restarted it (log entry 4) . This time the form was populated with data and I left it running until the PA stabilized around 0.0 to 0.1 acr min. Just as I stopped the assistant the star was lost as the clouds had completely covered the sky. The results of the guid assist are attached, I accepted the settings, and then closed up for the night. One thing I noticed, is that with 1 second exposure the HFD of the star was 6-7, but with faster exposures the value dropped to 1.5-1.8. Although the guide assistant did report the focus could be improved. I might try searching the net for a bahtinov mask for the SW finder so that I can see if I can get better focus. The thing is the computer and scope are in two different rooms making it hard to adjust focus whilst being close enough to the screen to see the results. PEC was not activated in this short test session PHD2_GuideLog_2020-04-13_200715.txt

Do you mean setting the sliders in EQMod... if so what rates would you like me to set and would 30 minutes per log be OK

Hi Michael, Yes the seeing wasn't great last night, the sky was fairly "milky" and then clouded over altogether as you can see by the end of the log file. The DEC Comp box was checked by default. I unchecked it to see if it made any difference. I'll reinstate it for the next session. When you say that calibration should be at Declination zero degrees, I was always under the impression you calibrated on a star in the field of view of the target rather than on some random star at zero dec ? So planned course of action for the next session. Focus finder / guider using PHD2's star image to get a low HFD Load up PHD2 and locate a gude star on or near the meridian at zero Declination Check the stars HFD Confirm DEC Compensation is checked Reset all settings under the Algorithms tab of the settings. Run the guide assistant and accept any settings it advises Calibrate and run a guide session for 30 minutes (regardless of any warnings when calibrating ?) Re-calibrate and run the same guide session, this time with PE enabled Should there be any other points to add to the list ?

OK, scope tracked for just over an hour, and all seemed as it should. I've attached screen captures of EQMod settings. The driver correctly had the right information when opened, which was confirmed by re-selecting the HEQ5/Sirus 4:1 option. The two images on the right were the before and after the run which lasted just over the hour. I've also included a screen capture of CdC showing it was locked on the position throughout the test Comments on a postcard please..... Hopefully if we get a clear night I'll try the other suggestions, having attempted finer focusing on the star as suggested

Last nights log file attached - only thing I changed was the exposure - reduced to 1s to see if the sampling rate made any difference. PEC was running I've also attached the PHD2 settings as they were. Running a 1hr test on RA at the moment - seems to be running fine. PHD2_GuideLog_2020-04-11_205622.txt

@alacant Yes it is a very out of focused star. To check collimation running the focuser to the end of its travel in both directions and taking an image will show up any errors in the optical alignment. If you get a nice round image, that has evenly spaced concentric diffraction rings (as shown) then it means the optics are collimated. Any errors in star shape is thus not down to a mis-aligned optical path. @michael8554 Thanks for the additional things to look at. I'll post up last nights log later this afternoon, and report back on the settings in the software.

Thanks for the in depth analysis. It's given me a fair amount to go through and check. This was a complete fresh overhaul of the scope after it had been sitting unused in the observatory for almost 4 years. Optics were removed, cleaned and reinstalled- focuser squared to the tube and the optics collimated with a Hotech laser in self centering adapters. Star test proved good as shown above. I did use APT's focus aid, but normally just adjust the Bahtinov mask pattern by eye. Focus on the finder guider was done on the moon, so could probably do with adjustment, but the only way to do so is screwing the finders objective in or out so its not as precise, but will see if I can sharpen the focus a little better. The PC was a fresh install of windows 10 64bit. I then downloaded the current versions of EQMod, ASCOM, Sharpcap, PHD2 and installed my old copy of APT. I only use APT for controlling the 400D DSLR which works well, so no need to change. The latest version of CdC was also installed. The mount is belt driven (I was messing about with belt conversions in 2011, and effectively proved the concept before Dave from Rowans used his CNC to make the kits we see in the shops). The ratio is 4:1 and this has been selected in the "driver" set up (but will confirm tomorrow). PA was done using Sharpcap as shown above. Once the first target was synced in CdC goto's have been spot on (from park to star two nights in a row). If the belts were slipping (which they are not) or the ratio was out then Goto would be way out. I will see how well the mount tracks a star unguided with no PEC, and then enable PEC to see if there is any issue there. The events shown in the log were my attempts as seeing if there was any dramatic impact on the guide graph having hovered over each item and reading the help text. Other than that everything was left at default other than entering the details of the focal length of the finder as 181mm based on info found on this forum. On the last 1hr 23m guide I believe the application selected the guidestar. The guide camera is an original QHY5 mono - under windows 10 I have to use the ASCOM driver in order to get an image, although the native driver works with QHVideo. When I installed PHD I simply followed the wizard. Nothing else was run other than the initial calibration routine. GA was not run (new to me). I do remember that in the original PHD under the brain icon there used to be a button that having inputted the focal length of the guide scope one the button was clicked it came up with the thresholds for various things including pulse length etc... that seems to be missing or is now called something else. Initially both RA and DEV guide rates were set to x0.5 - I tried x0.9, but dropped it down. I'll reset it for the next session. I'll grab the log for the last session and upload that, although the cloud cover may have screwed the data ?? and upload it in the morning. I'll also confirm the EQMOD settings (seems there are now presets rather than having to enter the values manually, but like I said above, if RA was set to the default ratio for the handset goto would be way off. It may be a few days before I get any further log files given the forecast for the next few days....

When checked PHD complained about RA being x% of DEC - I noticed that whilst calibrating, the East West would not count up and down correctly... it would say go from steps 1- 16 counting up a digit at a time, but when going the other way it would jump from sat 12 to 7, then 5, then 4, 3, 2. With the compensator unchecked it would count the steps up and down equally in all directions... unless it was stepping correctly, but just not displaying it. I also noticed that the N/S steps were always around half the E/W number of steps when calibrating.

Michael, the log file is attached - When zooming in on the image the stars looked OK to me PHD2_GuideLog_2020-04-10_203526.txt

Maybe not.... Just remote desktopped into the observatory PC and this was the result...... where did all that come from, it was crystal clear 1o minutes ago !

If I get time tonight I might have a look at that and give that a go (disabling EQMODs PEC) and see how it compares....

I'm no expert, but I think all that happens when you record the PE using EQMOD is that it's effectively logging the corrections PHD2 is making, and then after it has enough cycles it then works out the error and generates its own PEC file, rather than importing a PHD logfile, removing the non harmonics, and then creating the PEC file which is loaded into EQMOD. I'm running another guiding session as I type this, having used last nights log files to produce said PEC file. PEC was off whilst calibrating, but running whilst guiding. Its early into the session, but so far the traces in PHD seems a lot smoother, and when I left the RA/DEC errors were still below 1px, but that was only after 15 minutes or so. I'll probably post the results up tomorrow to see how they compare

Dave, apologies, it looked "plasticy" from the image. Thanks for clarifying the construction. Would it be possible to apply enough tension to cause the stretching, unless something was used between the mount and motor to exert the tension, but even then I would have though steel reinforced belts would be up to that ?

Do they use plastic belts in that kit ? When I was developing the concept of a belt drive conversion of the HEQ5 ( https://stargazerslounge.com/topic/121114-heq5-experiments-with-belt-drive/ ) I used reinforced MXL pitch rubber timing belts (from Beltingonline ) and they are still going strong - no signs of stretching or perrishing after 9 years in the observatory. Might be worth looking at getting alternatives if the belts in Rowans kits degrade after a few years ! Replacement from Rowan is priced at £4.95. The belts I used cost me less than £3 plus postage for the pair back in 2011, so I would guess even with inflation rubber belts may be cheaper. I never used any idle wheel in my design, but then I opted for a 4:1 ratio as I use EQMod to control the scope. Dave at Rowans machined the small gear to give the same ratio as the original gear drive so the hand set could be used, and added the idle wheel to increase the amount of belt in contact with the teeth on the smaller pulley. Maybe it's the constant inward and then outward flexing that has caused the belt to fail ? Hope you get it sorted soon.

Thanks for the comments guys, and masjstovel I have no objections to you posting the request here. @jimjam11 Several of my previous attempts to calibrate resulted in messages saying the RA was X percent of the DEC, yet both were set to use x0.40 rates under pulse guide settings in EQMod. The only setting I changed in PHD2 was to uncheck the option for DEC compensation which resulted in no warnings after calibration. Looking at the images whilst guiding all the stars are nice and round I've used PECPrep to generate a PEC file and will load that into EQMod and try a repeat of the guide session if the sky is clear tonight. I wasn't intentionally out to do an imaging session last night, but took advantage of the fact and ran off 25x 180s subs at 400ISO + 40 darks and here's the resulting image stacked in DSS using default settings - I'm quite happy with my first attempt in nearly four years

Whilst refreshing my mind with the virtues of PHD I came across this tutorial.... https://youtu.be/Mt0luBLaHDw It explains what to do with your ST4 and on camera settings