malc-c

Here's the comparason

Yeah, I think you're right, It's been fun learning what all the bells and whistles in PHD2 do... but I think in my journey documenting the process of getting hung up on seeking the holy grail of a perfectly flat line and tight clustering on the target graph raises several points. One of those that I found interesting was that I did a comparison of a single sub taken when I inadvertently left out details of the guidescopes focal length with one I took of the same target last night having created a new profile with that information correctly entered. At full frame, looking at the same groupe of star there was absolutely no difference in shape or size of the stars between the images. Now maybe I have been lucky and managed to hit that sweet spot on the balance and CofG and my PA an PEC are good enough that this omission had no impact. Or it could highlight an "issue" with PHD2 in that the numbers are all meaningless ? - Comparing the two target graphs they were so different, but there was no difference in the resulting image Anyway, onwards to the next learning stage, how to process and get the most out of the data I'm capturing 😉

Well the stars are round so it must have worked

Thanks for the tip. Log file attached.... best trace was the last.... I'm guessing that for an HEQ5 / 200P having those RMS values is a good result ? PHD2_GuideLog_2020-04-19_210404.txt

OK, well as its clear tonight I thought I would run one last series of tests, and this time the focal length of 181mm was correctly entered. I'll upload the log file later as I'm running a series of subs on NGC2903 and will stack them later to see if the stars are any worse or better. So to start with, having set the scope to 00:00:04 DEC and 08:50:55 RA I did a run of around 20-30 minutes. I then ran the guide assist four times (restarting the tool each time) and accepted and applied the suggested improvements after each time. I've attached the screen captures of the final three - The final result was a backlash value of 804. I then pointed the mount at NGC2903 and began guiding. Comparing the screen grab to the one shown at the same settings uploaded on Wednesday the trace is slightly but noticeably improved, and a lot flatter. But the target graph is more scattered, presumably as with the focal length inputted this affects the spacing ? I'll upload the log file tomorrow so you guys can comment on how good or bad the mount / scope is performing

For some reason this didn't get uploaded the other day One final image, NGC 2309. Again, just a stack of 18 x 240s subs and 18 matching darks - I'm happy with that, and no doubt with processing would be even better

Alacant, I think you have a point. So often we get wrapped up with trying to seek perfection that we never get round to actually doing astronomy. Regardless of what happened last night's PHD trials, I'm happy with the resulting images. I still need to perfect my processing skills, but that's a topic for a different day, but here is the results of 16 x 400s subs and 16 x 400s darks stacked in DSS. No flats, bias frames etc.... I've resized the image, but took a crop around the galaxy from the full frame.... stars look round to me I might try one more profile this evening just to see what the results are from curiosity... I'm guessing that as Michael has commented, with the backlash reduced and the results from the guide assistant the scope's balance and CG along with low backlash and decent star profile values it should mean the traces should be good. All I know is last night resulted in one of the sharpest images of M81 I've ever had.

Here's my take... When it was calibrating it moved the star 20 steps in X direction and back in Y, then 20 steps in A and back in B recording how many pixels or parts thereof it moved. It then starts guiding based on its algorithms or simply applying corrections based on the star movement. If the star moved 1 pixel in direction X it corrects sending a pulse it calculated to move the mount 1 pixel in direction Y thus maintaining the stars position, thus guiding. If the weather holds I might try another run, but this time ensure the focal length is entered. I'm guessing I could always load in last nights profile again if the results go really wrong ?

[removed word]... I thought it was too good to be true.....But it worked I must have missed that when I created the new profile - but then I ran the wizard, and would thought you couldn't move on to the next page without entering the info...... It is perplexing though.... enter the focal length, and I bet the guiding will be all over the place.... leave the focal length out, and run the calibration and you get amazing results that keeps the mount almost perfectly pointed.... If this is the case then what's the point of specifying the focal lengths.

Log file attached PHD2_GuideLog_2020-04-15_203913.txt

Ian, If you haven't already stumbled across my thread on resolving my issues with tuning the guiding on my HEQ5 have a read here https://stargazerslounge.com/topic/351622-phd2-graph-comments-please/ The attached screen grab is after a 40 minute run - I'm able to take 4 minute exposures with no issue. Its all down to balancing the mount, polar alignment and removing the backlash. I would recommend spending £10 and purchase SharpCap Pro if you haven't already done so. Use its polar alignment routine and get the polar alignment as good as you can. Ensure the scope is balanced and the center of gravity is as close to the balance point (Astronomy shed videos on youtube are an excellent resource). Then its just a matter of fine tuning the backlash on the mount... I was about to throw in the towel as it took me several attempts, but patience is a virtue

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