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Broken frames in Firecapture

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#1 Tulloch

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Posted 19 September 2021 - 06:53 PM

Hi there, I've recently changed my USBTraffic settings in FireCapture to 95/100 and have noticed that I seem to be getting a few "broken" frames from my camera. This is an intermittent issue, sometimes I get a few, sometimes none. Fortunately AS!3 identifies these as the "best" frames and puts them at the font of the stack so its easy to remove them with the spacebar, but I'm wondering where they come from and how to stop them in the first place.

 

Are these caused by a dodgy USB3 cable? High USBTraffic settings? Something else?

 

FC Chopped frme.PNG

 

Thanks,

 

Andrew


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#2 Ittaku

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Posted 19 September 2021 - 08:13 PM

A failure in USB communication, usually limited by your computer hardware when run at the limit of communication. I've had similar even with high quality USB cables and it only went away when I upgraded my laptop, or run lower frame rates. Fiddling with the USB speed settings didn't seem to help me and I found it a very blunt tool for dealing with USB communication problems at best. However, if you found it only started when you changed the USB speed settings, why not change it back?


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#3 Tulloch

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Posted 19 September 2021 - 08:46 PM

A failure in USB communication, usually limited by your computer hardware when run at the limit of communication. I've had similar even with high quality USB cables and it only went away when I upgraded my laptop, or run lower frame rates. Fiddling with the USB speed settings didn't seem to help me and I found it a very blunt tool for dealing with USB communication problems at best. However, if you found it only started when you changed the USB speed settings, why not change it back?

Because I like not having to reduce my FOV when imaging Jupiter at 150 fps, that's why :).

 

Looks like a reduction in FOV and USBTraffic is my only answer, oh well.

 

Thanks for the quick reply flowerred.gif


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#4 Ittaku

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Posted 19 September 2021 - 08:50 PM

Because I like not having to reduce my FOV when imaging Jupiter at 150 fps, that's why smile.gif.

 

Looks like a reduction in FOV and USBTraffic is my only answer, oh well.

 

Thanks for the quick reply flowerred.gif

Or you could do like me and ignore all the trend towards insanely fast frame rates, look at the actual research out there, and discover there's not much point going so fast. I do all my captures at 30fps.


Edited by Ittaku, 19 September 2021 - 08:51 PM.

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#5 Borodog

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Posted 19 September 2021 - 08:53 PM

Or you could do like me and ignore all the trend towards insanely fast frame rates, look at the actual research out there, and discover there's not much point going so fast. I do all my captures at 30fps.

What was your exposure time and frame rate on that phenomenal Jupiter you posted earlier?



#6 Ittaku

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Posted 19 September 2021 - 08:54 PM

What was your exposure time and frame rate on that phenomenal Jupiter you posted earlier?

30fps, I already spilled the beans earlier smile.gif It was a 10 minute derotation. I never use a ROI, just cut-out.


Edited by Ittaku, 19 September 2021 - 08:59 PM.

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#7 Tulloch

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Posted 19 September 2021 - 09:00 PM

Sure, but having started at 30 fps with my DSLR, and I'm really enjoying the higher frame rate with the 224. 30fps is fine if your mount is stable and there is no wind to blow it around, but that's not my mount ...


Edited by Tulloch, 19 September 2021 - 09:01 PM.


#8 dcaponeii

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Posted 19 September 2021 - 09:01 PM

It's the story of my existence.  If I drop my fps below 4 ms I start to see it even at small ROI.  Full frame it's just a normal occurrence for me.



#9 Borodog

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Posted 19 September 2021 - 09:25 PM

30fps, I already spilled the beans earlier smile.gif It was a 10 minute derotation. I never use a ROI, just cut-out.


Are you also saying you used ~30ms exposure time? Because if you did you must have had superb seeing.

#10 Kokatha man

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Posted 19 September 2021 - 09:33 PM

Andrew - this is termed "tearing" & is something that ccd & cmos cameras experience from time to time. I have never read any reliable explanations for its occurrence & fortunately appears to be a random camera malfunction that is pretty rare...we've experienced it at times but not for a long time now... but as said, when it has happened it pops up & then disappears for a long time before coming back. ;)


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#11 Tulloch

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Posted 19 September 2021 - 09:43 PM

Sure, but having started at 30 fps with my DSLR, and I'm really enjoying the higher frame rate with the 224. 30fps is fine if your mount is stable and there is no wind to blow it around, but that's not my mount ...

...and I did do some tests with the 224 at around 100, 200 and 300 fps for Jupiter. I eventually decided that 150fps was best for me, however that was only the result of one test so it was hardly a scientific investigation ...

 

 

Andrew - this is termed "tearing" & is something that ccd & cmos cameras experience from time to time. I have never read any reliable explanations for its occurrence & fortunately appears to be a random camera malfunction that is pretty rare...we've experienced it at times but not for a long time now... but as said, when it has happened it pops up & then disappears for a long time before coming back. wink.gif

Thanks Darryl, it's not too much of an issue as it's easy to fix, but would still prefer to not having it occuring if possible - I'll play around with a smaller FOV and a lower USBTraffic value.



#12 Ittaku

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Posted 19 September 2021 - 09:58 PM

Are you also saying you used ~30ms exposure time? Because if you did you must have had superb seeing.

33.3ms Yes I do set it to that exactly. (I used to set it to 33.33 but it always fell short of 30fps). I find the last part amusing - if the seeing's good the seeing's good regardless of what frame rate you are using, but also if the seeing's bad the seeing's bad also regardless of what frame rate you're using. Contrary to (apparently?) popular belief, the higher frame rate of lucky imaging helps stabilise the normal atmospheric distortion you get; it doesn't fix seeing, and doesn't "see through" bad seeing. I've tried it on many occasions in bad seeing comparing the lower and higher frame rates. The capture qualities remain garbage, but more importantly equally garbage in my experiments.

 

 

...and I did do some tests with the 224 at around 100, 200 and 300 fps for Jupiter. I eventually decided that 150fps was best for me, however that was only the result of one test so it was hardly a scientific investigation ...

Sure thing, and inspired by your work, I regularly do a comparison just to make sure I'm not dreaming, and the higher fps regularly just makes more work for me and doesn't give me a better outcome at all.  The paper I saw showed less than 1% relative increase in proportion of lucky frames going from 30 to 60fps, and no I did not keep the reference. They concluded it was an exponential function which makes complete sense.

 

One thing that might matter is perhaps my stacking and sharpening technique has evolved around working with low gain frames and their intrinsically much lower noise, and that I should be approaching it differently, but if the proportion of stacked frames remains the same, I fail to see how that could explain it.

 

At the very least, video derotation is much faster... tongue2.gif


Edited by Ittaku, 19 September 2021 - 09:59 PM.

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#13 Borodog

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Posted 20 September 2021 - 07:52 AM

33.3ms Yes I do set it to that exactly. (I used to set it to 33.33 but it always fell short of 30fps). I find the last part amusing - if the seeing's good the seeing's good regardless of what frame rate you are using, but also if the seeing's bad the seeing's bad also regardless of what frame rate you're using. Contrary to (apparently?) popular belief, the higher frame rate of lucky imaging helps stabilise the normal atmospheric distortion you get; it doesn't fix seeing, and doesn't "see through" bad seeing. I've tried it on many occasions in bad seeing comparing the lower and higher frame rates. The capture qualities remain garbage, but more importantly equally garbage in my experiments.

 

Thank you very much. You mentioned "research"; do you have a link to what you were referring to?



#14 dcaponeii

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Posted 20 September 2021 - 09:38 AM

I'll add a bit to the conversation.  All during my continuing battles with the residual astigmatism in my scope it has become clear that the best way for me to fight it is by using lower percentage stacks.  BUT what I can also add is that 1% stack at 200fps is still as good as 1% stacks at 60 fps but there are a lot more frames in that 1% stack at 200 fps and the noises levels reflect that increases number of frames even though the Gain has to be higher to achieve them.



#15 CrazyPanda

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Posted 20 September 2021 - 10:28 AM

I find the last part amusing - if the seeing's good the seeing's good regardless of what frame rate you are using, but also if the seeing's bad the seeing's bad also regardless of what frame rate you're using. Contrary to (apparently?) popular belief, the higher frame rate of lucky imaging helps stabilise the normal atmospheric distortion you get; it doesn't fix seeing, and doesn't "see through" bad seeing. I've tried it on many occasions in bad seeing comparing the lower and higher frame rates. The capture qualities remain garbage, but more importantly equally garbage in my experiments.

 

I have to disagree with this. You're correct that shorter exposures cannot fix geometric distortions present in a given moment of time, but it *does* reduce blurring as those distortions change shape.

 

I absolutely do see more blurring at 30ms than I do at 4-5ms.

 

I can get good results at 4-5ms, but I'd have to throw them away if I used 30ms.

 

That said, I do use 30-45ms and lower gain to aid in focusing.

 

EDIT: thinking about this some more, I have another argument to make, which is a thought experiment of what you would prefer given two choices:

 

1. Single 30ms exposure

2. Six, 5ms exposures

 

In the first instance, you might have steady seeing for 20ms, and then in the last 10ms, some bad turbulence comes in and blurs the frame. Now that frame is completely wasted, including all 30ms of data.

 

In the second scenario, at least you got four good frames and you only have to throw out two. So you at least get 20ms of good data instead of 0ms of good data.

 

And yes, seeing conditions can vary on the millisecond level.


Edited by CrazyPanda, 20 September 2021 - 01:25 PM.

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#16 wxcloud

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Posted 20 September 2021 - 10:34 AM

Seen similar shutter blind effects with my new asi224 first outing wasn't bad but next was. It was so bad I couldn't use the camera, it choked froze sputtered and was unusable between that and the image shift with the edge 8 I couldn't image, had to go to a USB 2 camera (asi290mm mini). Haven't figured out if it's the camera or just the laptop choking on the data. I'm leaning towards laptop as it's old and has the processing power of a raspberry pi I suppose.


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