looking for some dusk and dawn time lapse logs - Script Writing - CHDK Forum

looking for some dusk and dawn time lapse logs

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Offline Mlapse

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looking for some dusk and dawn time lapse logs
« on: 01 / November / 2021, 15:52:28 »
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I'm looking for the Tv96, Sv96 (or ISO), Av96 (or f:) and Bv96 values from some popular models to compare data between different models when running in P mode.
modern G,M or SX models would be nice.

and logs that are made around dusk or dawn would be ideal....assuming they contain that data per shot.

if somebody has some to share, thanks  :)
« Last Edit: 03 / November / 2021, 05:09:14 by Mlapse »
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Offline c_joerg

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Re: looking for some dusk and dawn logs
« Reply #1 on: 02 / November / 2021, 10:17:41 »
That depends a lot on which scene the camera recognizes. For example, I got values ​​of f2 1/1000s, ISO400 in P on my S110 and asked myself why the exposure time is so short and the ISO so high.
Under similar conditions there was then f2 1 / 250s, ISO80.
M100 100a, M3 101a, 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

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Offline Mlapse

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Re: looking for some dusk and dawn logs
« Reply #2 on: 02 / November / 2021, 10:46:27 »
Yes, preferrably i would have logs with the lowest iso possible for a specific cam model, but i can mostly recalculate those values if i have the iso value with a tv96 and bv96 value.

i'm looking for the longer exposure values, from 1/60-1second or more if your cam supports it.
and by then your cam will be fixed on the highest iso you have allowed in your settings and ISO will not change anymore if you haven't fixed it to a value.
So any log that includes one or more time lapse sunrise or sundown will be helpfull...
i already have data on the s110, s95 and a480.
« Last Edit: 02 / November / 2021, 11:24:44 by Mlapse »
frustration is a key ingredient in progress

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Offline c_joerg

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Re: looking for some dusk and dawn logs
« Reply #3 on: 02 / November / 2021, 12:13:29 »
So any log that includes one or more time lapse sunrise or sundown will be helpfull...

I have rawopint.csv log files from all of my timelapses. All the information is there. However, I don't know if you can do anything with it. The exposure is not controlled via the P mode. The script does the exposure control.
Here you can find some log files:
https://chdk.setepontos.com/index.php?topic=12761.0

M100 100a, M3 101a, 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


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Offline Mlapse

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Re: looking for some dusk and dawn logs
« Reply #4 on: 02 / November / 2021, 13:32:41 »
thank you, but they should be shot with P mode. it's hard to tell what is the result of canon or of the tweaks you made in rawopint.

I know the M10 goes up to 15sec in P mode, but have no logs anymore of that cam.
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Offline c_joerg

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Re: looking for some dusk and dawn logs
« Reply #5 on: 03 / November / 2021, 02:59:13 »
thank you, but they should be shot with P mode.

The P mode is the worst possible mode for time lapse. You have absolutely no influence on which parameter is changed in which size. Even if the camera only changes the exposure time, the 1/3 EV changes cause flickering. With CHDK, the exposure can be changed in 1 / 96EV steps flicker free.

M100 100a, M3 101a, 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

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Offline Mlapse

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Re: looking for some dusk and dawn logs
« Reply #6 on: 03 / November / 2021, 04:45:48 »
in that case, i'm looking for some failed P shoot of a dusk or dawn time lapse log :)
i'm only looking for data at this moment, although it's nice to see a beautyful video, thanks.

with only 3 older sensors it's a bit thin to mould it into reliable information.
« Last Edit: 03 / November / 2021, 04:54:41 by Mlapse »
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Offline reyalp

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Re: looking for some dusk and dawn time lapse logs
« Reply #7 on: 03 / November / 2021, 13:40:19 »
Like c_joerg, I only have rawopint logs, but perhaps we could help if you describe what you are trying to get from this. In general the relationship between Bv and the exposure values is governed by the APEX equation. Obviously the available Av/Tv/Sv depend on the camera, and there's some room for camera specific variation (in the definition of Sv, the details of metering, and how the AE allocates between the available exposure parameters), but IMO it would be difficult to characterize them from logs like this, and it's not clear what you'd gain.

If you want fine grained control of exposure, I suggest controlling it yourself, either based on the camera Bv from half shoot or using raw data like rawopint.

That said, if you provide a ready to run script that logs what you want, I could potentially take some runs on g7x, sx710 or sx730.
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Offline Mlapse

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Re: looking for some dusk and dawn time lapse logs
« Reply #8 on: 03 / November / 2021, 14:01:55 »
there is no reason to go out of your way to make logs, i'm sure a few will turn up eventually.
and i've got data from 3 cams, so enough numbers to start.
yes, working with an apex equation.
but can't tell you yet what i'm looking for...only when i've found it, i'll know.

I might have found what i'm looking for, and the answer is not 42, but closer to 271  :)

So although i am still happy with other logs.
the more pertinent, easy to answer, question is...
are there models that still have a positive BV when switching to 1 second exposure when at lowest ISO at a midrange aperture (f: 3-4)?.....in P mode

for most older 1/2.3 it is Bv96 -96=>1sec, also true for the 1.7 ccd of the s95.

but the s110 already shifts to 1 sec (Tv96 15) at Bv96 -7...so i can imagine 1 inch or larger or just a modern sensor would still have positive bv numbers at 1 sec....no need for a whole log, just want to know if it happens at all ...and approximately how much.

since aperture changes that.
values above are at 50mm eq (S95 f:3.1, S110 f:3.4).
f.i. at 28 (f:2.0) on the S95: Bv96 -96=> 0.4sec)

i would suggest an equivalent to 50mm or somewhere halfway your zoom to get proper values.
 
« Last Edit: 04 / November / 2021, 08:36:53 by Mlapse »
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Offline reyalp

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Re: looking for some dusk and dawn time lapse logs
« Reply #9 on: 04 / November / 2021, 13:31:27 »
Tv + Av = Bv + Sv => Bv = Tv + Av - Sv

G7 X
Wide open at 50mm equivalent = F2.5 = 267
Base ISO = 125 = 511 ("market" and "real" are the same on this cam)
Tv = 1s = 0

Bv = 0 + 267 - 511 => -244 => -2.5 APEX

Note that the better (more sensitive / light gathering) a camera is, the *more* negative Bv will be for a given shutter speed, since Bv is a measure of the actual amount of light, and a more sensitive camera needs less light to get correct exposure.
Don't forget what the H stands for.

 

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