proposal - script shooting hooks - page 24 - General Discussion and Assistance - CHDK Forum

proposal - script shooting hooks

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Offline udo

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Re: proposal - script shooting hooks
« Reply #230 on: 20 / August / 2015, 09:02:15 »
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Interesting findings.
Does this mean we need ND control in the script?

(to stay `below` 1/1000 and to have control...)
« Last Edit: 20 / August / 2015, 12:37:38 by udo »

Re: proposal - script shooting hooks
« Reply #231 on: 20 / August / 2015, 15:30:45 »
I made 3 isoinc runs. Single, Quick and continuous mode. It looks like, that continuous mode works but the ND has less than 2 steps…

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Does this mean we need ND control in the script?

You have to set your camera in continuous mode. And you have to switch ND on after every new start. May be it is different on your cam. But I look like that the ND is different to the other cams. I would use additional the aperture on minimum f=5.6.
« Last Edit: 20 / August / 2015, 16:32:00 by c_joerg »
M100 100a, M3 101a, 2*G1x (101a,100e), S110 (103a), SX50 (100c), SX230 (101a), S45,
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Offline reyalp

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Re: proposal - script shooting hooks
« Reply #232 on: 20 / August / 2015, 16:41:31 »
I made some testing with ND on SX230. I was wondering, that the ND is always off, when I switched the camera on. Is the parameter not saved?
There is an option to clear overrides on startup, which is enabled by default.

The overrides are only actually applied on half-shoot.

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Continuous Mode with AF:  ND is active only on first shoot, all the other shots the ND is inactive.
Since CHDK overrides are applied in half press, this isn't really a surprise. I'd consider it a bug, but probably not easy to fix. The rawopint script may have other trouble in this mode too, since it assume the canon firmware keeps everything fixed after the first shot.
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But when I do a full press, without waiting for focusing, the ND is always inactive, independent from the mode.
This is a is also a bug. This case often takes a different path in the canon code and has issues, so it isn't much of a surprise either.

Can you check whether other overrides (Tv, ISO, Av)  are applied and whether raw is saved in case?
Don't forget what the H stands for.

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Offline udo

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Re: proposal - script shooting hooks
« Reply #233 on: 21 / August / 2015, 09:01:39 »
Hmm..
I had the sx260 in P mode and set continuous mode before starting the script.
I enabled the ND filter ('in').
Yet I see exposure times below 1/1000th when checking the EXIF of the images.

The sky looks OK.
The buildings on the ground look a bit underexposed at times.

I also see some dark parts in the foreground light up white at times...
« Last Edit: 21 / August / 2015, 09:56:14 by udo »


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Offline reyalp

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Re: proposal - script shooting hooks
« Reply #234 on: 21 / August / 2015, 16:22:38 »
Hmm..
I had the sx260 in P mode and set continuous mode before starting the script.
Is it continuous with AF, or standard continuous? c_joerg's results suggest that continuous + AF doesn't handle the ND correctly on sx230. It's likely that other cameras with the same feature suffer similar problems.
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I enabled the ND filter ('in').
Yet I see exposure times below 1/1000th when checking the EXIF of the images.
Since your camera as an adjustable aperture, you could set that in canon controls (using M or Av mode) before shooting.
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The sky looks OK.
The buildings on the ground look a bit underexposed at times.

I also see some dark parts in the foreground light up white at times...
It's impossible to have any useful comment on this without seeing the results.
Don't forget what the H stands for.

Re: proposal - script shooting hooks
« Reply #235 on: 22 / August / 2015, 04:46:45 »
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There is an option to clear overrides on startup, which is enabled by default.
Interesting, I never used overrides before….
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The rawopint script may have other trouble in this mode too,
Yes, it was only a test, I don’t want to use continuous AF mode with rawopint…
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Can you check whether other overrides (Tv, ISO, Av)  are applied and whether raw is saved in case
I checked ISO and Av override. It work on all modes and also with half and full press.
I checked RAW only on single mode (because of crashing in continuous mode). It works with half and full press (override Av + RAW).

@udo:
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The sky looks OK.
The buildings on the ground look a bit underexposed at times.

Well, it is your decision what you want. The script can’t change the dynamic of your senor.
Especially against the sun:  You can have a

1) neutral sky and underexposed ground
or
2) overexposed sky and neutral ground.

My decision is always neutral sky and underexposed ground. When you use RAW, you can rescue the underexposed ground. But this didn’t works with overexposed sky…
« Last Edit: 22 / August / 2015, 05:02:07 by c_joerg »
M100 100a, M3 101a, 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 udo

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Re: proposal - script shooting hooks
« Reply #236 on: 22 / August / 2015, 09:35:36 »
Hmm..
I had the sx260 in P mode and set continuous mode before starting the script.
Is it continuous with AF, or standard continuous?
No AF. Just continuous.
Less flickering in the video than before!

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I enabled the ND filter ('in').
Yet I see exposure times below 1/1000th when checking the EXIF of the images.
Since your camera as an adjustable aperture, you could set that in canon controls (using M or Av mode) before shooting.
I'll do a run with lower aperture next time and hope for ND filter support in the future... ;-)

In Av mode aperture dial goes to 8 but the Av override goes to 16. (does anything over 8 work on the sx260?)
What would be the best way to use an aperture setting? Via Av mode or via CHDK overrride?
CHDK mode is easiest to do; also in there I can override the distance to infinity.
« Last Edit: 22 / August / 2015, 11:30:17 by udo »

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Offline reyalp

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Re: proposal - script shooting hooks
« Reply #237 on: 22 / August / 2015, 16:24:45 »
What would be the best way to use an aperture setting? Via Av mode or via CHDK overrride?
In theory, either should be OK. I suggested using canon controls because they are less likely have bugs or special quirks than CHDK controls.
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In Av mode aperture dial goes to 8 but the Av override goes to 16. (does anything over 8 work on the sx260?)
Maybe, maybe not. In general, it's likely that you can go higher than at if you are zoomed in with the optical zoom, but the exact details are up to you to determine by experiment, if you care.
An example on sx160 http://chdk.setepontos.com/index.php?topic=12297.msg121510#msg121510

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CHDK mode is easiest to do; also in there I can override the distance to infinity.

Regarding the video you sent me in PM:
I don't see any obvious defects except for a very small amount of flicker. I'm not sure which "darker spots" you are referring to, I see shadows on the ground and birds (and maybe bugs or other debris close to the camera) on the sky.

As c_joerg says, you always have to trade how much over exposure you want to accept against how dark you want to allow the rest of the scene to get. The script offers you a lot parameters to adjust this, but you will probably need to do many runs to get a good feeling for how they work.  I'll try to provide a few comments suggestions.

First, a general description of how it works:
* The script uses two measurements to control exposure: A "meter" area centered in the scene, and a histogram of the entire scene.
* The exposure system tries to keep the average value of the meter at some target exposure value, and uses the histogram keep over and under exposure within some limits.
* By default, the meter is 30% of the sensor width and height, something like spot metering mode in the canon firmware. Stuff outside of this area only influences exposure if it reaches the histogram limits.
* By default, the target exposure value for the meter is a "neutral" exposure, roughly what what Canon AE would give if you aimed the camera at a uniform grey subject.
* The meter target value, limits, and balance between meter and histogram control are all adjustable in the script settings. The individual settings are described in the readme.

Some notes on this specific run:
* Meter was the default 30%, which is mostly sky in this scene.
* The log shows that the exposure was almost entirely driven by meter. The meter_weight, over_weight and under_weight columns show the relative contribution of meter and histogram over and under exposure limits.
* Since you set Underexp thresh to 0, under exposure is ignored. The under_frac column shows there was substantial under exposure, with 15-20% of the scene -4 ev or below.
* There was some over exposure toward around 3/4 of the way through the run, but over_weight never exceeded 1 (except the very start before the algorithm settled), so it had very little impact.

Some things you could do differently
* In a normally composed landscape scene, the sky is bright and should be more exposed than "neutral". So if your meter mostly on the sky, you may want to use the script "Ev shift" option to increase the target exposure. I'd suggest +1/4 to +1/2.
* Alternatively, you could use a larger meter, so it would include the ground. You can use something like 90% if you want.
* If you had under exposure protection enabled, it would have pushed the exposure higher until the sky started to hit the over exposure and / or meter high limits. You can use the "max weight" and "prio" options to control the relative influence if there is both under and over exposure.
* Since the meter is mostly on the sky, clouds moving by cause the brightness of stuff on the ground to change even when the actual lighting hasn't changed. You can use the "Bv Ev shift" option to reduce this effect. This adjusts the target exposure by the absolute brightness of the scene. I find a value around 30% gives reasonable results. The "Bv Ev shift base" option controls sets the brightness at which there is no shift. "First" uses the initial exposure. A well lit subject in daylight would be around 10.
Don't forget what the H stands for.


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Offline udo

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Re: proposal - script shooting hooks
« Reply #238 on: 23 / August / 2015, 11:43:46 »
Did another timelapse.
This one was in Av mode with aperture at 8.
Exposure still shorter than 1/1000 at times because over time the sun was visible in the picture when the clouds did not obscure this luminous object.
I am quite happy with the results.

Re: proposal - script shooting hooks
« Reply #239 on: 24 / August / 2015, 12:31:46 »
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This one was in Av mode with aperture at 8.
Together with ND?

I always use ND. I never do it without against the sun and never on midday.
I made a couple of runs against the sun (you can see it on sides before) with G1x and S110.
I don’t find a run which is higher than 1/500. Ok the ND is one step higher...
M100 100a, M3 101a, 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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