Problems using CHDK with Canon S110 - Script Writing - CHDK Forum
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Problems using CHDK with Canon S110

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Offline jmgc

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Problems using CHDK with Canon S110
« on: 30 / November / 2015, 11:03:05 »
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Hello CHDK Community,


I'm using CHDK scripting with the Canon S110 for a while, but recently I've found that the parameters introduced in the script menu (exposure, aperture, iso) doesn't affect the photos in same way as if we manually take a photo - in the exactly same conditions of light.

During the script run, the S110 works as expected, the photos are beeing recorded with the parameters defined earlier, but most of the the time they are always overexposed when compared to the same photo, same light, but taken manually.

Problem: there's no truly relation between the parameters defined with the script and the photos taken.
In the same conditions, a photo taken manually is visual more/less exposed than a photo taken using CHDK.

Desperately, I found a way to minimize this problem.
Using the overrides, I can adjust the values a little more or a little less and go checking the photos, until they seem fine.
But still can't trust the settings.

This is getting really annoying, there's anyone around with this kind of problem and a possible solution?

Cheers!
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Offline waterwingz

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Re: Problems using CHDK with Canon S110
« Reply #1 on: 30 / November / 2015, 11:23:32 »
What script are you using?

Be aware that if you override any value, then you need to set them all. The Canon firmware does not know that you have set one and does not compensate appropriately.
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Ported :   A1200    SD940   G10    Powershot N    G16
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Offline jmgc

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Re: Problems using CHDK with Canon S110
« Reply #2 on: 30 / November / 2015, 12:09:52 »
Hi waterwingsz,

I'm using the KAP-UAV with little modifications (zoom to infinity, quicker shutter speed)
Besides the overrides, therer's any known explanation to the fact that the the scripts keeps writing certain parameters while the S110 uses others slightly different?

Thanks.
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Offline waterwingz

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Re: Problems using CHDK with Canon S110
« Reply #3 on: 30 / November / 2015, 12:19:55 »
Did you actually modify the code? Or just change some of the script parameters from the script menu?

Edit : It seems like there are four possible things that could be wrong here :
  • There is a fundamental defect in CHDK
  • There is  problem with the kap_uav.lua script
  • There is something wrong with the CHDK port for the the S110
  • PEBKAC

It seems unlikely that this is a bug in CHDK itself, or in the kap_uav.lua script.  With over 4500 downloads of the script, this has never been reported by anyone else.  And I have taken thousands of pictures on several different camera models without noticing any routine overexposure.

If there is something wrong with the CHDK port for the S110, it should show up in other scripts and would probably have been reported by now.  But it is possible there is an issue.

So that leaves the possibility that the issue is related to something you are doing.  Please post the KAP.log file found in the main folder (root) of your SD card?  Also,  please send me a download link for a couple of example photos - some taken "normally" and some with the kap_uav.lua script. It would be good if the images take by the script are ones that have information stored in the KAP.log file.

Once I have a log file and some images it will be easier to determine what might be happening.

« Last Edit: 01 / December / 2015, 22:50:00 by waterwingz »
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Ported :   A1200    SD940   G10    Powershot N    G16
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Offline jmgc

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Re: Problems using CHDK with Canon S110
« Reply #4 on: 02 / December / 2015, 04:51:39 »
Hi waterwingz,

Thanks for your concern.
I'll be running some tests and I'll send you the log files and pgotos for your appreciation.
« Last Edit: 02 / December / 2015, 05:01:34 by jmgc »
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Offline jmgc

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Re: Problems using CHDK with Canon S110
« Reply #5 on: 06 / January / 2016, 05:37:30 »
Hi waterwingz,


I've done some test and I've got some issues.
Since I've used the same values to the Tv/Av/ISO min/targe/max should't the camera be forced to use this values to take the photos?
This isn't happening. Any guess?
« Last Edit: 06 / January / 2016, 05:43:39 by jmgc »
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Offline waterwingz

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Re: Problems using CHDK with Canon S110
« Reply #6 on: 06 / January / 2016, 08:45:05 »
Quote from: jmgc on 02 / December / 2015, 04:51:39
I'll be running some tests and I'll send you the log files and photos for your appreciation.
Quote from: jmgc on 06 / January / 2016, 05:37:30
I've done some test and I've got some issues. Since I've used the same values to the Tv/Av/ISO min/targe/max should't the camera be forced to use this values to take the photos? This isn't happening. Any guess?
I'm going to need to see the log file before I can comment.

edit :  see also these posts KAP & UAV Exposure Control Intervalometer Script
« Last Edit: 06 / January / 2016, 09:32:53 by waterwingz »
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Ported :   A1200    SD940   G10    Powershot N    G16
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Offline jmgc

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Re: Problems using CHDK with Canon S110
« Reply #7 on: 06 / January / 2016, 09:54:44 »
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Offline waterwingz

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Re: Problems using CHDK with Canon S110
« Reply #8 on: 07 / January / 2016, 08:57:00 »
Quote from: jmgc on 06 / January / 2016, 09:54:44
Replied via PM
Quote from: jmgc on 06 / January / 2016, 10:04:18
Photos and kap.log: xxxxxxxx . The first photo was taken manually, and the others using kap script. Notice that the Tv value changed from the first photo the others. What i'm seeking is to measure the values (manual mode) and to use them with the script, without any change in the image or parameters.

The Tv value in all your photos is given as 1/1000 in the image exif info.  Where did you see something that says that it changed?

Having said that, it's clear that when you compare the first image to the others, the exposure has changed a bit (maybe 1/2 f-stop worth).  That is strange as the image exif exposure information is identical for each image.

I have no explanation for this - or at least not yet.  I did notice two things in the log file that you could check.  You have the camera's ISO setting manually set - can you change that to AUTO mode please? Also,  you have the camera in Tv priority mode - can you change that to P mode? Let me know if either of those changes corrects the exposure difference?
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Ported :   A1200    SD940   G10    Powershot N    G16
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