Automatic Flash even in manual mode - Feature Requests - CHDK Forum
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Automatic Flash even in manual mode

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Offline 7heEnd

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Automatic Flash even in manual mode
« on: 25 / July / 2011, 05:43:32 »
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Hi all,
My Canon sx20 gives the possibility to select the power of flash in manual mode and also CHDK has this feature.
The power of flash could be set at low, middle or strong.
Nevertheless, it seems that camera has more than 3 levels: I don't understand how to obtain the same flash's power of a shot in which flash is automatically managed by the camera (e.g. in Av mode).
I will explain the problem with an example:
The following shots were taken in a room with low light; the wall was about 1,5meter far.

-  Shot 1: http://imageshack.us/photo/my-images/838/img0229cu.jpg/
Mode Av; Av 2.8; Tv 1/60; ISO 200; Flash popped up;
In mode Av it is the camera that manages the power of flash. I only set Av and ISO and camera selected Tv and flash. It seems that it does 2 quick low flashes.

However, I rarely use Av or Tv modes.
I usually shot in Manual mode
-  Shot 2: http://imageshack.us/photo/my-images/190/img0230ru.jpg/
Mode M; Av 2.8; Tv 1/60; ISO 200; Flash popped up @ LOW power;
In manual mode, setting everything as the previous shot, the low power flash results to be not enough.
Well, let's try to use the middle power.

-  Shot 3: http://imageshack.us/photo/my-images/339/img0231qu.jpg/
Mode M; Av 2.8; Tv 1/60; ISO 200; Flash popped up @ MIDDLE power;
The flash is definitely too powerful and the shot is unusable.

I wish chdk gave the possibility to set also a flash-power like the one used by the camera in the first shot (which is more than LOW but less than MIDDLE); I also think that an automatic flash mode would be useful even in Manual mode (Ok, I want to set Av, Tv, flash On/Off and ISO level, but flash power - in addition to focus - should be managed by camera if I prefer so).

Any advise about doing this task with the current CHDK? It may be a main chdk proposal...

P.S. Of course I know that in Av mode I could use chdk override to set flash power; anyway, in manual mode I am forced to set the flash power (both with canon menu and CHDK), so I would like to override this Canon setting thanks to CHDK with the automatic control of the flash.
« Last Edit: 02 / May / 2012, 11:52:37 by 7heEnd »
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Offline 7heEnd

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Re: Automatic Flash even in manual mode
« Reply #1 on: 05 / October / 2011, 12:06:13 »
No opinion about this?
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Offline 7heEnd

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Re: Automatic Flash even in manual mode
« Reply #2 on: 02 / May / 2012, 11:51:03 »
Why didn't I get an answer? Maybe my post is too long...?
I still wonder if I can get a flash power which is stronger than the LOW level but less than MIDDLE.
Thanks to anyone should try to understand my question :)
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Offline waterwingz

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    • Waterwingz
Re: Automatic Flash even in manual mode
« Reply #3 on: 02 / May / 2012, 22:23:48 »
Quote from: 7heEnd on 02 / May / 2012, 11:51:03
Why didn't I get an answer? Maybe my post is too long.?
While it helps to post short specific questions,  the usual reason for not getting an answer is that either nobody knows the answer or nobody is personally interested enough in your problem to spend time working on it.  CHDK is an all volunteer group - there is no official staff.  People work on what interests them.  In your case,   I suspect nobody else really cares about having a manual flash power level between low and medium.

Quote
I still wonder if I can get a flash power which is stronger than the LOW level but less than MIDDLE.
To provide manual flash power levels,  it was discovered that CHDK could write a value of 0,1, or 2 to one of the propcase memory registers and that would cause the camera to fire manual flash at low, medium and high power.   CHDK does not actually control the flash - your camera does that.  It just specifies which of three power levels to use.  So unless you want to spend a lot of time digging into the internals of Canon code to figure out how to override the flash power,  3 levels is all that you are likely to get.
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Offline 7heEnd

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Re: Automatic Flash even in manual mode
« Reply #4 on: 03 / May / 2012, 05:37:04 »
I didn't want to seem insistent, I just was wondering why nobody answered since I think my question could be interesting. Sorry about that.

I provided photos to show that camera - in auto flash mode - can use a power for the flash which is among LOW and MIDDLE and it is very very useful when you have to shot close portraits.

Can anyone advise me what is a way to manage flash in such situations? How do you get an optimal shot in full manual mode?

Chdk can't include an automatic override set? I mean flash power: 0, 1, 2 and AUTO
« Last Edit: 03 / May / 2012, 05:41:12 by 7heEnd »
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Offline DryDuck

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Re: Re: Automatic Flash even in manual mode
« Reply #5 on: 03 / May / 2012, 13:11:49 »
Quote from: 7heEnd on 03 / May / 2012, 05:37:04
Can anyone advise me what is a way to manage flash in such situations? How do you get an optimal shot in full manual mode?

Chdk can't include an automatic override set? I mean flash power: 0, 1, 2 and AUTO

As stated in a previous reply, that can only be done if you are prepared to look deeply into Canons firmware code.
However you can get the same effect using Overrides. In Tv mode you can use the "Override Aperture Value" setting or in Av mode you can use the "Override Shutter Speed Value" to get the camera to automaticly control the output of the flash.


DryDuck!
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Offline 7heEnd

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Re: Automatic Flash even in manual mode
« Reply #6 on: 05 / May / 2012, 10:50:47 »
I am not prepared to manage firmware and codes, but I hope it will be done a day by someone who can and also thinks this would be useful. Could it at least be added in the poll about chdk proposal? :)

Anyway I want to thank you for the time spent answering and the smart advise on how getting the same effect. ;)
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