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Reducing the minimum exposure speed in High-speed Burst HQ mode

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Offline longtalker

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Re: Reducing the minimum exposure speed in High-speed Burst HQ mode
« Reply #10 on: 11 / January / 2014, 16:55:27 »
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Thanks very much, I really appreciate it! I will have access to my camera in 2 days, and will report back then.

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Offline longtalker

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Re: Reducing the minimum exposure speed in High-speed Burst HQ mode
« Reply #11 on: 16 / January / 2014, 18:32:57 »
OK I tried this, and the slower exposures show up correctly in the menu. THe camera is also able to use them in Custom Auto ISO mode, however the ISO selected is too low, leading to underexposure. For instance, in a low light setting, where I would expect my slowest acceptable exposure to be selected (1/4s), the Auto ISO should go at something like 800 in order to correctly expose the photo - instead, it always stays at 100, it seems, even though I've set the maximum ISO to 3200 in the menus. I seem to remember the old CHDK that I had was setting the corect AutoISO with the same menu settings - it just didn't have exposures slower than 1/8.

Let me know if you think you'll have the time to implement those other changes you were mentioning, if so I will not yet customise this current version but instead wait for the final one. Many thanks in advance!

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Offline longtalker

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Re: Reducing the minimum exposure speed in High-speed Burst HQ mode
« Reply #12 on: 16 / January / 2014, 18:40:35 »
Oh and also, was there a way to just apply this particular change (extension of possible exposures list) to my old CHDK, so that I don't have to redo all custom menus etc? I've seen the .patch file in the attachment but wasnt sure how to use it.

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Offline longtalker

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Re: Reducing the minimum exposure speed in High-speed Burst HQ mode
« Reply #13 on: 26 / January / 2014, 11:46:44 »
Let me know if you need any testing for it...


Re: Reducing the minimum exposure speed in High-speed Burst HQ mode
« Reply #14 on: 26 / January / 2014, 12:58:33 »
Oh and also, was there a way to just apply this particular change (extension of possible exposures list) to my old CHDK, so that I don't have to redo all custom menus etc? I've seen the .patch file in the attachment but wasnt sure how to use it.
Patch files are used to modify the CHDK source code.  It's a way to work on things on one computer and when its done, allow you to merge your changes back into the master copy of the source code.  Very handy when working on a project with multiple people writing code.  But I also use them with my personal code - scripts & core CHD stuff - which I maintain in a version control system (svn).

Having said that,  you do not have to redo your menu setups and other customizations each time you load a new release of CHDK.  Once you have your bootable SD card formatted correctly,  you only need to "unzip" the most recent CHDK distribution file to the SD card root (making sure to select the option that uses or "preserves" the folder structure in the zip file).  This means you do not need to repeat the complete original installation process you followed (STICK?) - that will wipe out all your customizations and reformat everything from scratch.

One small exception to the above can happen when moving between CHDK versions ( 1.0.0 -> 1.1.0 -> i.2.0 -> 1.3.0 ).   Even there,  I think there was an atempt made to automatically use the old config files in the new version.

I seem to remember the old CHDK that I had was setting the corect AutoISO with the same menu settings - it just didn't have exposures slower than 1/8.
I'll take a look but there has been nothing changed in Custom AutoISO since it was added (other than the conversion from real to market ISO some time ago).   I've looked enough at the code to be somewhat afraid to touch anything there. 

In fact, problems with the working of that function  (Is Custom Auto ISO working for the A640 under 1.2?) were the reason I got started on a "small" script to replace it.  Hundreds of hours later it looks like this :  KAP_UAV_Exposure_Control_Script
At some point I think it would be good to recode the AutoISO portion of that script in "C" and replace the existing code.

FWIW :  CHDK AutoISO was added to core CHDK back when the German and International version of CHDK were merged.  At that time, the CHDK-DE version had a lot of "experimental" code.  I'm pretty sure the function would not get added today without a lot more work and testing.

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Let me know if you think you'll have the time to implement those other changes you were mentioning, if so I will not yet customise this current version but instead wait for the final one. Many thanks in advance!
Like I said above,  go ahead with your customizations.  You will not lose them if you are just updating the CHDK core code.



tl;dr :  can you reload the CHDK 1.3.0 version for you camera from the autobuild (which will not have the extended shutter speeds) and verify that it sets the exposure correctly ?

« Last Edit: 26 / January / 2014, 13:28:47 by waterwingz »
Ported :   A1200    SD940   G10    Powershot N    G16

Re: Reducing the minimum exposure speed in High-speed Burst HQ mode
« Reply #15 on: 26 / January / 2014, 15:14:38 »
Update :  Loaded the patched version onto my A1200 and did some testing.   Despite what I said about the code above, it does seem to work - with the extended range patch and without.

One little thing that I did notice.  The Canon ISO mode on the camera needs to be in ISO AUTO for the Custom AutoISO feature to work.  If the camera is set to a fixed ISO 100 (for example) then it will stay at 100 and the resulting exposure will be wrong.
Ported :   A1200    SD940   G10    Powershot N    G16

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Offline longtalker

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Re: Reducing the minimum exposure speed in High-speed Burst HQ mode
« Reply #16 on: 01 / March / 2014, 18:37:32 »
Hey, sorry for the late reply!

Another problem aside from the exposure values being limited to no slower than 1/8 (which it seems was easily fixed by simply adding 1/4, 1/2 etc to the list) was that the camera would under no circumstances select an ISO higher than 400. Instead, for dark scenes, it would select the minimum exposure speed (1/8s) and the max ISO (400), which would of course result in under-exposed pictures. Is this limitation also easy to fix, i.e. could you just make it possible for AutoISO to also take values above 400? If so, that would really make the feature very useful, as you could just shoot in high-speed burst mode under any brightness conditions, and you'd just have the ISO 'penalised' accordingly while maintaining the exposure speed as slow as you can be confident you can manage with a hand-held camera.

Re: Reducing the minimum exposure speed in High-speed Burst HQ mode
« Reply #17 on: 01 / March / 2014, 18:43:50 »
Another problem aside from the exposure values being limited to no slower than 1/8 (which it seems was easily fixed by simply adding 1/4, 1/2 etc to the list) was that the camera would under no circumstances select an ISO higher than 400. Instead, for dark scenes, it would select the minimum exposure speed (1/8s) and the max ISO (400), which would of course result in under-exposed pictures. Is this limitation also easy to fix, i.e. could you just make it possible for AutoISO to also take values above 400? If so, that would really make the feature very useful, as you could just shoot in high-speed burst mode under any brightness conditions, and you'd just have the ISO 'penalised' accordingly while maintaining the exposure speed as slow as you can be confident you can manage with a hand-held camera.
Isn't that what the "Fallback Max ISO" and "Fallback Min. Shutter Speed" settings are supposed to do?
Ported :   A1200    SD940   G10    Powershot N    G16


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Offline longtalker

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Re: Reducing the minimum exposure speed in High-speed Burst HQ mode
« Reply #18 on: 01 / March / 2014, 18:45:40 »
Are they? I didn't see those options anywhere..

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Offline longtalker

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Re: Reducing the minimum exposure speed in High-speed Burst HQ mode
« Reply #19 on: 01 / March / 2014, 18:48:19 »
Oh yes I see in the 1.2.0 manual that those options would have to be there under the CustomISO menu - however, I don';t have them in the version that I reverted back to (sx40hs-100f-1.2.0-2246-full_BETA)

 

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