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rawopint.lua: Fast, accurate intervalometer with raw exposure metering

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Re: rawopint.lua: Fast, accurate intervalometer with raw exposure metering
« Reply #190 on: 07 / February / 2023, 07:44:49 »
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So:#ui_meter_low_limit_e=4
#ui_exp_over_thresh_frac=1000
#ui_exp_under_thresh_frac=20000

Have I understood that correctly?


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Offline reyalp

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Re: rawopint.lua: Fast, accurate intervalometer with raw exposure metering
« Reply #191 on: 07 / February / 2023, 12:19:07 »
So:#ui_meter_low_limit_e=4
#ui_exp_over_thresh_frac=1000
#ui_exp_under_thresh_frac=20000

Have I understood that correctly?
Yeah, something like that should handle similar scenes with less overexposure.
Don't forget what the H stands for.

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Offline c_joerg

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Re: rawopint.lua: Fast, accurate intervalometer with raw exposure metering
« Reply #192 on: 08 / February / 2023, 03:42:01 »
So:#ui_meter_low_limit_e=4
#ui_exp_over_thresh_frac=1000
#ui_exp_under_thresh_frac=20000

Have I understood that correctly?

Overexposure is always a big problem. Overexposure and underexposure cannot be controlled at the same time. That's why the underexposure is always switched off (ui_exp_under_thresh_frac=0) for me.
 
Code: [Select]
#ui_exp_under_thresh_frac=0 "Underexp thresh x/100k (0=Off)"
M100 100a, M3 121a, G9x II (1.00c), 2*G1x (101a,100e), S110 (103a), SX50 (100c), SX230 (101a), S45,
Flickr https://www.flickr.com/photos/136329431@N06/albums
YouTube https://www.youtube.com/channel/UCrTH0tHy9OYTVDzWIvXEMlw/videos?shelf_id=0&view=0&sort=dd

Re: rawopint.lua: Fast, accurate intervalometer with raw exposure metering
« Reply #193 on: 08 / February / 2023, 12:45:25 »
OK, still using the old rawopint (have one more experiment running with the latest version and will post). This time I stopped the dark frame subtraction and switched off raw shooting, and the interval was a very solid 15s. In my real life shoot neither the sun nor the moon will be making an appearance so please keep that in mind when reviewing the rawopint data. Attached is also a picture of the set up. Had the camera running for 26 hours and the powerbank still didn't run out of juice. This shoot as a video:
I'm very happy with the result, and am looking foreard to the next full moon which is when I hope to do the real shoot.


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Offline reyalp

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Re: rawopint.lua: Fast, accurate intervalometer with raw exposure metering
« Reply #194 on: 08 / February / 2023, 19:54:21 »
This time I stopped the dark frame subtraction and switched off raw shooting, and the interval was a very solid 15s.
From the log, the minimum value "sleep" is 220 ms, so you've got pretty close to the minimum interval with your chosen settings. It's pretty stable so you could probably  use ~100 ms shorter interval or longer exposure without exceeding the interval, but neither will make a big difference.

Quote
In my real life shoot neither the sun nor the moon will be making an appearance so please keep that in mind when reviewing the rawopint data.
That should certainly make things easier.

Looking at the most recent run, most of the night is on the exposure limits (max ISO, longest shutter) so in this segment the effect of the under exposure and low meter limits is to make the script more resistant to moving exposure in the other direction. In other words, making the under exposure limits stricter wouldn't brighten the scene. Relaxing them or making the over exposure limits stricter would potentially allow the scene to get darker in response to areas of overexposure.

If you want to get more exposure at night, you might get away with upping the ISO a bit. Assuming your target is 1080P youtube playback or similar, downscaling from 16 MP reduces the noise you see quite a bit compared to a full res still. If you do, you should test in advance, because  the Canon firmware introduces various levels of noise reduction (other than dark frame) at various ISO levels, which add to processing time. So you might find that setting ISO 360 breaks your interval, while ISO 359 does not (numbers made up).

c_joerg may disagree, but I think these settings are a reasonable compromise. The moon would look better with less over exposure, but not at the expense of making the foreground totally dark. Letting the scene get a little darker might be better compromise, but it's a subjective call, and if you want to see the landscape, the moon itself is going to be blown out.

Similarly, the bright lit windows in the nearby building are over exposed, but the rest of the scene getting darker when they go on would likely be distracting.

Fortunately, it sounds like neither of these should be issues in the real shoot.

For me, the worst over exposure in this run is probably right around sunrise (starting around 2:30, corresponding to the over exposure peak of ~2.78% around frame 3918). Again may not be an issue for your real shoot if the sun won't be rising directly in view, but it's a case where controlling overexposure more would probably look better. Further relaxing the under exposure limits (increasing under_thresh_frac or turning it off) would probably help there.

The flip side of this is, once the sun actually comes into view, it's going to over expose no matter what, so you still have to decide how dark you want to allow the rest to get. But again, allowing it to get a little darker would probably be fine. However, in this case, when the sun is in view, you hit the short shutter limit of 1/10000, so making the limits stricter wouldn't make the scene darker anyway. You could allow even shorter shutter speeds, but 1/10000 is already pretty extreme, and pushing the limits may result in flickering (though it seems fine here)

Note the meter limits are not active (meter weight == 100) in the sunrise section. Roughly half the scene is bright and half is dark, so the average exposure is great :haha. In a case like this, you could bias the meter to favor the sky or ground by adjusting the height and position. E.g. if you want to focus on sky colors, metering only the top half of the scene, or if you want the landscape, only the bottom. Or 2/3 if you want favor one but still have some influence from the other. Not suggesting this applies for your current project.


Overall, my suggestions if you want to tune further form this run would be:
1) Explore increasing ISO, probably to something under 400, before the extra noise reduction kicks in
2) Increase under_thresh_frac to maybe 40%, or turn it off entirely (0) as c_joerg suggested.
Don't forget what the H stands for.

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Offline c_joerg

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Re: rawopint.lua: Fast, accurate intervalometer with raw exposure metering
« Reply #195 on: 09 / February / 2023, 03:39:33 »
c_joerg may disagree, but I think these settings are a reasonable compromise. The moon would look better with less over exposure, but not at the expense of making the foreground totally dark.

But that's exactly how I do it when shooting in the sun. The foreground is then quite dark. I then increase it in the RAW processing. That's the only way it works properly from my point of view. Of course, this only works with RAW and not with JPG. With a 12-bit RAW you are certainly more limited.
M100 100a, M3 121a, G9x II (1.00c), 2*G1x (101a,100e), S110 (103a), SX50 (100c), SX230 (101a), S45,
Flickr https://www.flickr.com/photos/136329431@N06/albums
YouTube https://www.youtube.com/channel/UCrTH0tHy9OYTVDzWIvXEMlw/videos?shelf_id=0&view=0&sort=dd

Re: rawopint.lua: Fast, accurate intervalometer with raw exposure metering
« Reply #196 on: 09 / February / 2023, 07:11:23 »
Does anyone have any idea why this shoot stopped prematurely? The log file stops @ 20:18 and the shooting itself @ 20:44. It doesn't appear to be the battery. Thanks.

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Offline reyalp

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Re: rawopint.lua: Fast, accurate intervalometer with raw exposure metering
« Reply #197 on: 09 / February / 2023, 13:05:40 »
Does anyone have any idea why this shoot stopped prematurely? The log file stops @ 20:18 and the shooting itself @ 20:44. It doesn't appear to be the battery. Thanks.
The fact the the log ends with an incomplete line suggests either a crash or a script error, but it doesn't provide any information beyond that.

Did the camera shut down? If so, was the lens extended or retracted?

If the camera crashed, there may be a romlog https://chdk.fandom.com/wiki/Debugging#Camera_crash_logs_(romlog), please post it if so.

Can you see what the number of the last actual image taken was? The log ends at 666  (:blink:) but it's buffered, so if the camera crashes some portion will be missing.

Was the camera on battery or external power?

edit:
If this happens and the camera doesn't shut down, it's likely a script error. In that case you should check Miscellaneous -> Console -> Display last console to check for script errors. But this is lost if the camera has been shut down.
« Last Edit: 09 / February / 2023, 13:19:58 by reyalp »
Don't forget what the H stands for.


Re: rawopint.lua: Fast, accurate intervalometer with raw exposure metering
« Reply #198 on: 09 / February / 2023, 13:44:38 »
The kkast picture taken was #769 and it appears normal. Camera was being run on an extrenal power supply. As I was expecting the camera to have shutdown after another 10 hours it was only after I had turned everything off that and removed the card that I noticed that something was amiss, so I have no idea what state the camera was in. Romlogging will be enabled the next time around. Sorry I can be of any further help.

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Offline reyalp

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Re: rawopint.lua: Fast, accurate intervalometer with raw exposure metering
« Reply #199 on: 09 / February / 2023, 13:48:22 »
Romlogging will be enabled the next time around.
The Canon firmware saves the romlog to internal flash memory when the crash occurs, so nothing needs to be enabled. You can get the most recent romlog by following the instructions on the linked wiki page.
Don't forget what the H stands for.

 

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