Sharpcap and Sequence Generator Pro

Somewhere to ask questions about the best way to use SharpCap
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admin
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Re: Sharpcap and Sequence Generator Pro

#11

Post by admin »

Hi,

Yes, the best workaround for delivering at the moment is to use live stacking and select to save the individual raw frames and (optionally) to view the raw frames rather than the stack. You can even turn off alignment in the live stacking options to save on CPU usage. Effectively you are using the dithering that is built into the live stacking and ignoring the stacking part of it.

Cheers, Robin
umasscrew39
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Re: Sharpcap and Sequence Generator Pro

#12

Post by umasscrew39 »

Hi Robin

ok- did not realize that. I'll use it that way for now to capture individual fits files, dithered in-between, to then stack in PI. Once this and a sequencer gets implemented in non-live stacking mode (which I think you said may come out in the next big version), it would make everything almost ideal for me with both SC and PI essentially covering everything I would ever need. I can live without the meridian flip and we discussed an auto-focus option previously and why that will not happen.

Bruce
chongo228
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Re: Sharpcap and Sequence Generator Pro

#13

Post by chongo228 »

admin wrote: Thu Apr 02, 2020 6:51 pm Hi,

I suppose that taking the ideal starting position a bit further might help – if the focus position was limited to a band of values that the user configured then autofocus might be more reliable – basically in the configuration you would set up that the best focus point was between 7000 and 9000 and that would give SharpCap both a good starting point and an idea of what range it should be looking within.

Cheers, Robin
I was thinking about this more and had an Idea that might be faster during an imaging session.

Could you also have a "refocus button"? When applied it would rack the focuser out a set number of clicks defined by the user from it's current position and then start the focus process from there. Instead of looking over a much larger range for initial focus this method could confine the process to a range common for temp changes and save time. My focuser moves about 20 to 40 every time I refocus due to temp changes. Over the night the autofocus scanning over several hundred positions would waste time. Could you have a "find initial focus" and "refocus" option

Initial focus would scan over a large range and need to be done to start an imaging run.

After that the faster "refocus" would back up 50 clicks, scan in 100 clicks, and then go to best score/position for example.
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Re: Sharpcap and Sequence Generator Pro

#14

Post by admin »

Hi,

Actually the biggest challenge to doing something like this is knowing how far you have to move to get out of the backslash zone. If you approached focus the first time from the negative direction then you need to move back in the negative direction at least far enough to unwind all the backlash in the mechanism and go a bit further before you then start your positive scan again (the beginning of which will be taking up backlash once again). I wonder if it would be a good idea to have a way to either measure or allow the user to enter a backlash figure? If you ran two focus scans in opposite directions then the difference in position of the point best focus should give you a good estimate of the backlash amount I think.

Cheers, Robin
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Re: Sharpcap and Sequence Generator Pro

#15

Post by chongo228 »

admin wrote: Mon Apr 20, 2020 6:01 pm Hi,

Actually the biggest challenge to doing something like this is knowing how far you have to move to get out of the backslash zone. If you approached focus the first time from the negative direction then you need to move back in the negative direction at least far enough to unwind all the backlash in the mechanism and go a bit further before you then start your positive scan again (the beginning of which will be taking up backlash once again). I wonder if it would be a good idea to have a way to either measure or allow the user to enter a backlash figure? If you ran two focus scans in opposite directions then the difference in position of the point best focus should give you a good estimate of the backlash amount I think.

Cheers, Robin
I always assumed that's what the backlash field under the advanced settings was for. I thought whatever value I entered in would be taken into account when the focuser would in another direction. See attached photo...

I've measured the backlash with calipers and performing the way you described above. I would right click the arrows to see the number location between where SC found perfect focus and take the difference. I think I did it about 5 times and took the average. I found my Moonlite and Feathertouch to both be around 20-25. So I just leave the backlash field at 25.....although I do find the value is blank a lot and I have to renter it. Seems like a simple tool you could add in being as all the info is already there.
focuser.JPG
focuser.JPG (165.36 KiB) Viewed 2202 times
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Re: Sharpcap and Sequence Generator Pro

#16

Post by admin »

Hi,

Unfortunately not all focusers offer that option of adjusting the backlash compensation, so SharpCap can't assume that the backlash will be dealt with by the focuser driver. :(

Cheers, Robin
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Re: Sharpcap and Sequence Generator Pro

#17

Post by chongo228 »

If some focusers can't compensate for backlash a field to enter a value in SC would not only be a good idea but a necessity.

The first few auto focus runs would probably work but as the night went out the auto sequence would get further and further off it's original starting point.
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Re: Sharpcap and Sequence Generator Pro

#18

Post by remyastro »

Hi All,

Very interresting discussion indeed !

Going on with SharpCap (nearly auto) focusing feature, as I wrote before, I am now using it satisfactory and I'd like to share some experience I have met while using it.

As chongo228, I use the EAF focuser on my 65/420 refractor,and I also have to refocus it from time to time as the temperature cools down during the night (I live in the Alps, where temperatures below 0 are quite frequent at night!).

BTW : I have'nt found any sensor temperature calibration curve in ZWO documentation sofar! Is the temperature sensor just a sales pitch for ZWO?

This is to highlight the real interest to design a fast refocus feature in SC, so that to ease long imaging sessions at night.
A pre-selected value seems less important for me now, as a can easily set it by hand because I always have a rough idea of it.

Your feeling Robin?
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Re: Sharpcap and Sequence Generator Pro

#19

Post by admin »

Hi,

I think it's probally best to proceed in steps – perhaps the first step would be to add the option for backlash compensation into SharpCap, initially allowing you to set it up manually. Next would be seeing if we can add a function to measure and auto set the backlash compensation figure. Once we are happy that the backlash compensation works well and allows small movements of the focuser in both directions without having to worry about the backlash, going to auto focus become simpler.

Cheers, Robin
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Re: Sharpcap and Sequence Generator Pro

#20

Post by chongo228 »

Temp compensation doesn't work. Or in theory it does until dew heaters come in to the mix and ad another variable the temp sensor can't see. I don't even have mine hooked up anymore. But if it did work the amount of compensation would differ from every scope, focuser, and dew heater power setting.

@Robin....although I want all the features now I agree with a soft roll out. One reason I've stayed with SC is because I find it very stable. In the 3+ years I've been using it I think it's only crashed once or twice....and all the functions have worked as expected. Autofocus will never work reliable and quickly if backlash isn't accounted for.

Down the road a initial focus and refocus would be awesome...at the end of the night focusing takes up a decent amount of time....perhaps as much as dithering......especially on my really fast refractors where I have to focus often if the temp drops. Only Voyager and NINA seem to have gotten auto-focus down for the most part. If you had a reliable and quick solution I bet it would sell a lot of PRO licenses....just saying :D
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