Focusers

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nexusjeep
Posts: 293
Joined: Thu Oct 18, 2018 3:01 pm
Location: Gloucestershire

Re: Focusers

#11

Post by nexusjeep »

Hi Ian,

It will be a bit tricky to match my settings as I built my own focuser rack and pinion gearing so it is a bit non standard as I needed to remove any slippage from the original 10:1 reduction. So for information my focuser moves 38,000 steps on the Sesto for a travel of 80mm as I leave 10mm dead either end, this equates to 0.0021 mm per step or near as makes no difference 2 microns per step.

For my APM LZOS 780/130 refractor with the various narrowband and LRGB filters my critical focus zone (CFZ) is between 60ish to 90ish microns depending on the filter in play. For my Autofocus setting I have SharpCap set to 20 steps per focus move so roughly 40 microns per move this will then always give me two focus points inside the CFZ so I should get a nice downward to upward curved on the graph in SharpCap in the CFZ. I take three shots at each position as shot 1 is usually not right as SharpCap currently runs in video mode so every time a frame stops another starts so every time the focuser moves this will happen in frame 1 of the three but the second 2 will be accurate as focuser movement has stopped. I do not do planetary shots so this might affect other frames if individual frame duration is shorter than the focuser move duration. I take fifteen sets of 3 shot samples but move the focuser out then in until it is just not in focus and then run the Autofocus scan in the inwards direction and stop it once the samples pass through the CFZ then tell Sharpcap to return to the best position.

I think I have read that the next major release of SharpCap will have the potential to run the camera in still mode which means that theoretically SharpCap could wait for the focuser to finish moving before initiating the next capture but Robin could confirm this, it would be quite beneficial if this is the case as with narrowband filters it is time consuming to keep losing the first shot on each focuser move but even with this I find that the routine works very well and is far easier than me trying to do it.

Hope this helps.

Cheers
Nick
SgtBilko
Posts: 9
Joined: Sun Aug 18, 2019 5:06 am

Re: Focusers

#12

Post by SgtBilko »

That's kind NIck
Thank you
Lothar
Posts: 2
Joined: Wed Sep 23, 2020 3:40 pm

Re: Focusers

#13

Post by Lothar »

admin wrote: Thu Dec 06, 2018 4:32 pm Hi,
any focuser that has an Ascom driver will be supported by SharpCap. You just need to make sure you have installed the Ascom platform and the focuser driver. Everything else you need to know is in the documentation in the hardware section.

Cheers, Robin
Hello there,

I am trying to integrate a Sesto Senso 2 with SharpCap.
Sesto Senso 2 comes with a ASCOM driver. The only configuration the ASCOM driver offers is the selection of the COM port.
(COM10 in my case).
My configuration:
- EAGLE3S running Win10
- ASCOM 6.4 SP1
- SharpCap 3.2.6433.0

Two issues:
1. The Sesto Senso 2 has a optional temperature probe fitted and I can see the temperature being read by the PrimaLuceLab's Focus Manager tool. However, in SharpCap I cannot tick the T.Comp checkbox.

2. When using the Bahtinov Mask Focus Assistant I do not see the "Graph" tab as I was expecting to see the focuser position and score. When using the FWHM Focus assistant, I can see the "Graph" tab with the focuser controls.

Please refer to the attached screenshots for illustration of the issues.
Screenshot 2020-09-23 at 17.53.53.png
Screenshot 2020-09-23 at 17.53.53.png (346.73 KiB) Viewed 1072 times
Screenshot 2020-09-23 at 17.53.09.png
Screenshot 2020-09-23 at 17.53.09.png (412.75 KiB) Viewed 1072 times
Note: Currently when trying this out the lens cap was fitted and hence no Bahtinov interference pattern could be observed.

Question 1: Would the "graph" tab become available once the Bahtinov mask is fitted and the sloping lines are detected ?

Question 2: Why can the T.comp checkbox not be activated ?

Any help appreciated.

Kind regards

Lothar
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admin
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Re: Focusers

#14

Post by admin »

Hi,

the ability for applications like SharpCap to control the temperature compensation of a focuser has only been added in the most recent update to the Ascom focuser specification (IFocuserV3) - it sounds as though the Ascom driver you are using doesn't support this new specification yet, so SharpCap has no way to control the temperature compensation or even know if it is available, meaning that the checkbox is disabled. You should still be able to turn temperature compensation on and off through the settings window for your Ascom driver.

I think that the graph display for the bahtinov mask will appear once you have some valid focus data from it – in your screenshot you just have an error message which is telling you that SharpCap hasn't yet spotted anything that looks like a Bahtinov pattern. That's certainly the way that it works for me – I just tested with the testing camera and a couple of different images of stars with/without a bahtinov.

Thanks, Robin
Lothar
Posts: 2
Joined: Wed Sep 23, 2020 3:40 pm

Re: Focusers

#15

Post by Lothar »

Hello Robin,

yes, this is correct. The focus Graph is now working for me with the Bahtinov Assistant and also the auto focusing is working very well on the first attempt.

Regarding the T.comp. - I think you are right. Feels like the ASCOM driver I am using does not support it (yet), the only options I have is to select the COM port and turn logging on/off. I might get back to the manufacturer on this one - although it is not a critical issue for me.

Cheers

Lothar
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