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Beginner questions

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Offline waterwingz

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Re: Beginner questions
« Reply #10 on: 18 / May / 2012, 08:51:11 »
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Quote from: reyalp on 18 / May / 2012, 01:33:33
Your concern is well founded. Ports without the fastest MD implemented correctly will not capture lighting very reliably. Unfortunately, there is no list as to which ones have this outside of the source code, and even if it is in the source, that doesn't actually mean it's implemented correctly.

Quote from: philmoz on 18 / May / 2012, 03:20:53
In addition the cameras from 2010 onwards appear to have longer shutter lag before the shot is taken - even if everything is set to manual.

None of the cameras I have ported can get under 140 - 150 milliseconds for MD response time.
I'm reasonably sure the viewport code is correct for the MD detect.
I have not personnally tried any lightening photography but does this suggest the Motion Detection wiki page should be updated with a caution that the performance of recent cameras will make reliable lightening photos difficult to obtain ?  I suppose if there was a reliable calibration method we could start a list of how fast each model is.  I've had mixed results with the links here http://chdk.wikia.com/wiki/Software#Motion_Detection - does anyone currently have a favorite ? 

Also,  this thread suggests that its not even a recent problem : Those 100ms lightning motion detection models, which are they?

I guess the question is :  How fast is good enough ?
« Last Edit: 18 / May / 2012, 08:56:57 by waterwingz »
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Offline outslider

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Re: Beginner questions
« Reply #11 on: 18 / May / 2012, 16:10:10 »
MD implemented correctly - what does it really mean? Is there a special par of the code, that has to be optimized for certain camera? How? MD on SX130is seems to be not very fast, so I would be interested in any suggestions what is to be done...
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Offline waterwingz

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Re: Beginner questions
« Reply #12 on: 18 / May / 2012, 16:19:27 »
Quote from: outslider on 18 / May / 2012, 16:10:10
MD implemented correctly - what does it really mean? Is there a special par of the code, that has to be optimized for certain camera? How? MD on SX130is seems to be not very fast, so I would be interested in any suggestions what is to be done...
It seems to be a matter of how well the vid_get_viewport_live_fb() function in sub/xxx/lib.c is implemented.  Fast versions track in real time which of several buffers the camera is using.  Slow versions just look at one of the several buffers (and so are delayed until the camera used that particular buffer again).

For example,  the sx130 has this :
Code: [Select]
void *vid_get_viewport_live_fb()
{
    return 0x0;
}
and the G10 has this

Code: [Select]
void *vid_get_viewport_live_fb()                        // G10 @ FF83A41C routine - match with IXUS980_SD990
{
    void **fb=(void **)0x2298;
    unsigned char buff = *((unsigned char*)0x20FC);
    if (buff == 0) {
        buff = 2;
    }
    else {
        buff--;
    }
    return fb[buff];
}

In the sx130 case,  the motion_detect.c just default over to the slower vid_get_viewport_fb when it gets a null return value from vid_get_viewport_live_fb.
« Last Edit: 18 / May / 2012, 16:27:41 by waterwingz »
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Offline whatalesyou1

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Re: Beginner questions
« Reply #13 on: 04 / June / 2012, 10:22:51 »
As much as I hate to admit it, I think you have sufficiently scared me away.  This would be strictly a hobby for me.  I just can't justify spending the money and time on this project to discover I am doomed from the beginning...

Thanks for the input and good luck to all on the project.

:)
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Offline whatalesyou1

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Re: Beginner questions
« Reply #14 on: 10 / September / 2012, 21:20:23 »
Well, I'm back with a slightly larger budget and a significantly larger sense of adventure!   8)

I have decided to move forward with a Canon and CHDK.  I am just wondering if anyone has had any success acquiring lightning with a G12 and a motion detection script.

Thanks!
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Offline waterwingz

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Re: Beginner questions
« Reply #15 on: 10 / September / 2012, 21:29:25 »
Quote from: whatalesyou1 on 10 / September / 2012, 21:20:23
I have decided to move forward with a Canon and CHDK.  I am just wondering if anyone has had any success acquiring lightning with a G12 and a motion detection script.
You might get more specific answers, but knowing who ported the G12,  you can safely assume its "as good as it gets" with CHDK on the G12.  If you can't capture lightening on that cam,  you are probably not going to capture it at all.



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Offline whatalesyou1

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Re: Beginner questions
« Reply #16 on: 11 / September / 2012, 10:34:35 »
LOL!!!   :lol

I already have a CHDK-crush on philmoz.
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