Seeing thresholding interaction with capture menu

[AstroMathmo]

I had my first try with the seeing trigger and filter tools at the weekend. This looks very useful given I am in Thames Valley at 120m, and torturing myself with solar CaK imaging.

I sort of got the controls to work, but am confused about the interaction with the settings in the main Capture menu. So I am using an Altair Hypercam 533M that runs at 40fps in MONO8, and prior to using the seeing tools might go for a full disc for a minute or two or maybe 3000 frames. The advice I have had is that up to 120s is fine for a FD. So what I would like to do is to something like set up a sequence of 5 video captures, each is bounded by 120s, and whatever the wait gap is in the Capture menu, have each video capture only commence when the seeing has got to my threshold. I'd like to then try either

(a) it just run each video through to 120s without further seeing filtering (so only a seeing trigger for the start of each stage);

(b) run each video to 120s with seeing exclusion (so both trigger to start each session and filtering within it).

I guess (b) will just save me disc space and AS4 processing time over (a) - either is good. I just need to be sure I stop at 120s even if it's a modest frame harvest in case b. TIA

PS - got the feature tracking work in centre of mass mode now for my FD. Great tool given my PA-rough daytime setup!

[admin]

Hi,

for the seeing monitor function, you only get the choice of how many frames to capture in the dropdown on the left - no choice in terms of time to capture for.

When you are using the 'triggered' option, you can calculate how long the recording will be from the number of frames selected and the frame rate, so at 40fps, setting 5000 frames will get you 125s. My instinct is that you are unlikely to get a good seeing period nearly as long as that, so the 'triggered' option would be better for shorter bursts of capturing.

When using the 'filtered' option, how fast you actually capture depends on the threshold level that you set - the camera might pull in 40fps, but you may be keeping on average only 10fps. Remembering that you are only keeping the best frames, you will likely end up stacking most of the frames that get captured this way, so set the number of frames to capture at a value that corresponds to the number of frames you usually get AS!4 to add to the stack from a longer unfiltered capture.

The final option - auto threshold capture - is good for a 'one click' approach. Set up plenty of memory for frame cache in the SharpCap settings when using this option. While capturing, it will fill memory with frames, then keep save the best 10% of them to file and throw away the rest (emptying memory) and then repeats until the number of captured frames is reached. No need to set a threshold manually.

cheers,

Robin

[AstroMathmo]

Thanks Robin

I'll work within those constraints for now - thanks for clarifying. I'm doing some full discs and was advised to keep below about 2mins to manage solar changes, so it would be good to have an upper bound on the time for the filtered and auto threshold option linked to that bound.

I'm very pleased with the filtering - even though I get smaller videos. Here is the first attempt

https://www.astrobin.com/full/m42v9p/0/

Cheers

William

[admin]

Hi William,

nice image - really good detail in there!

You can always press 'Stop Capture' if an individual video runs to more than 120s without hitting the frame count target.

cheers,

Robin

[AstroMathmo]

Right - I've got a grip on the auto-thresholding and it works very well. So eg for full discs I can target a video length in time by taking my camera frame rate and entering a total number for frames to be saved in the box at the left. So I can get my thresholded videos to be below 2 mins. With the Basler at 20fps 2mins gives me 2400 without filtering and I just select the largest number <= 240 on your menu.

These pre-filtered runs make Autostakkert run so much faster for obvious reasons - I can now take a look at 5-10 stacks while I give the scope a short break rather than doing it all later.

But now I have two requests to go on your dev wish-list:

1. Would it be possible to have the number of frames saved to be freely user-selectable rather than just picking the ones on a drop down?

2. And this is the one I really miss when using the seeing tools - could you add a loop option like there is in the main Capture menu? That way I can ask Sharpcap (with feature tracking on of course) to do something like produce ten seeing-filtered frame sets in a row without intervention, rather than having to click start every time? The addition of the time limit would also be good but I think the counts I am selecting get to the target number before I hit a time limit usually. It is the lack of a loop that still ties me to the PC, or stops me focusing on another PC task.

[admin]

Hi,

Good to hear the auto-filtering is working

It sounds as if the best thing here would be for me to add sequencer support for the auto filtered capture, so that it would be possible to write a sequence that repeats the capture. It would also be an easy way to allow customization of the number of frames to capture. I will look into that change.

cheers,

Robin

[AstroMathmo]

That would be great - auto-seeing filtering with the combination of sequencing and tracking would be a killer. I can do sequencing plus tracking already, but the gives me huge files and AS4 running like a dog, but the pre-filtering makes AS4 run super-fast.

Ta

William