SharpCap Forums

Hi,

the log is certainly consistent with SharpCap never detecting any significant motion of the image in response to commanding the mount to move. Unfortunately there is less detail than I would like available in the log because the information about movements of the mount and image only gets written to the log after the calibration either fails or succeeds... Not if it gets stuck

If you set the same '4x' speed in the manual mount movement controls on the right and use the direction buttons, do you see movement?

One thing to note is that if you are using a Celestron SE mount (or similar), these can have quite a large amount of movement backlash when switching movement direction, so it could take a long while at 4x to work through the backlash and then for the mount to actually physically start moving.

cheers,

Robin

Hi,

a little more digging on my part revealed that the missing logging does actually exist, but it is in a separate log file called 'GuidingLog_......... .log'. These guiding log files can be found in the same folder as the normal SharpCap logs. If you can dig out one or more of those logs I will be happy to have a look.

cheers,

Robin

Hi, thanks a lot
i have recovered guiding logs and attached also other logs about same night
thanks in advance

If you set the same '4x' speed in the manual mount movement controls on the right and use the direction buttons, do you see movement?

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i can say that if i use Scope control section i can always move the mount (regardless feature tracking status)

Hi,

thanks for posting the guiding logs - from the logs I can see that all the failures you are seeing with calibration are happening when trying to calibrate the altitude axis in the -ve direction (the +ve direction works). This is very likely to be backlash related - after moving in the +ve direction, the initial mount movements in the -ve direction do nothing to the pointing position of the telescope.

From my point of view, I need to change the code to allow more backlash allowance in case of this problem happening. I am not going to be able to make this change for a while as I am going to be away for much of August without access to cameras or telescopes.

I think you may be able to set up backlash compensation in the handset for Nexstar mounts, which may help with this issue. See https://nexstarsite.com/OddsNEnds/Backlash.htm

cheers,

Robin

Hi, thanks for your answer
so i have to regulate backslash in down direction;i will try to do it- in meantime have a nice vacation!!

Hi Robin
This is the other Mike here again.

Using my SW 14 inch GOTO Dob, I did manage to get it to calibrate a couple of times and get it to guide briefly using Mount Speed. I don't have the log, but I do have a screen shot. Yes, I know I should have used center of mass (It was 5 am)
How do you interpret the scatter graph on the right of the screen? I have the back of the scope overweighted. I think that helps with Alt backlash. I will try adjusting Az backlash compensation, but I think a similar mechanical solution is needed for Az. Perhaps a giant elastic band, or tilting the scope.

CS
Mike

Hi Mike,

I would expect to see arrows on that graph indicating the corrections that were being made to the position in response to the target being away from the 0,0 center point - I'd also expect the corrections to have moved the red crosses much closer to 0,0 after a while. So, overall, I'm a bit surprised that the graph looks like that. Did you see any corrections being made after you shifted to guide mode?

cheers,

Robin

Hi Robin,

Ok, I am glad that it doesn't make sense to you. I was puzzled as well. I only saw the arrows indicating corrections made in ROI mode. Not absolutely sure if corrections were being made when I switched from calibration to guide. At the time, I thought it was, bit then again it was 5 am! Will give it another try soon. And will try and capture the log!

Best

Mike

Hi Mike

Yes that guiding screen does not look correct it shows guiding there was movement and then no correction. Once i get calibration to work mine guides well i am too using a 14 inch scope a meade ACF. The only time you should get a display movement and no scope movement is if its in the dead zone area setting but i can see 5 pixels set so that should be ok, One think i do see different to mine is in the guiding rate box on mine there is no guiding rate option name just guide rates like 1x,2x,4x i normal used 1x or 2x try that.

Mike

Hi Robin

As to you question

what happens with the barlow if you use a slower movement rate for calibration (perhaps even down to the guiding rate?) That should cancel out some of the effect of the barlow in making the object move faster/further.

I get the same error about movement rates so not match same as my original problem due to the calibrate movement rate added to the sidereal rate in one direction.

Mike