Permanent Exposure Lock? - Feature Requests - CHDK Forum
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Permanent Exposure Lock?

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Offline s5-user

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Permanent Exposure Lock?
« on: 15 / August / 2008, 10:25:12 »
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It would be really nice if a "permanent exposure lock" function could be added.
The exposure lock only works for the next shot and then is gone and you have to lock again and again...

Thank you
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Offline fe50

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Re: Permanent Exposure Lock?
« Reply #1 on: 15 / August / 2008, 11:52:51 »
Quote from: s5-user on 15 / August / 2008, 10:25:12
It would be really nice if a "permanent exposure lock" function could be added.
The exposure lock only works for the next shot and then is gone and you have to lock again and again...

Do you mean the Canon AEL feature ? This normally stays active until you press the UP key (on Ixus series) again or you use the zoom...
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Offline cybercom

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Re: Permanent Exposure Lock?
« Reply #2 on: 15 / August / 2008, 12:15:24 »
Well, an AEL that stays locked while zooomnnng would be great!
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Offline whoever

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Re: Permanent Exposure Lock?
« Reply #3 on: 15 / August / 2008, 12:52:01 »
Quote from: cybercom on 15 / August / 2008, 12:15:24
Well, an AEL that stays locked while zooomnnng would be great!
Ehm... But you change Av when zooming, don't you? So your further shots would be over/underexposed? But you could perhaps track zoom events and call DoAELock() (firmware function) upon each change, which would save you two button presses.

P.S. Aah, I forgot, you're a stereo-geek...
« Last Edit: 15 / August / 2008, 12:57:34 by whoever »
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Offline ewavr

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Re: Permanent Exposure Lock?
« Reply #4 on: 15 / August / 2008, 13:14:39 »
Why not, all is possible... On some keypress CHDK must read propertycases for ISO, Av, Tv, then turn on Av, Tv, ISO override mode and set corresponding variables...  On lens zooming camera can recalclutate Tv ( or ISO).
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Offline s5-user

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Re: Permanent Exposure Lock?
« Reply #5 on: 16 / August / 2008, 01:16:43 »
In the detailed camera's user manual (canon S5 IS) states that (Page 84):

You can set the exposure and focus separately.
This is effective when the contrast is too strong between the subject and background or when a subject is backlit.

Locking the Exposure Setting (AE Lock)

Shooting Mode: Video, P, Tv, Av.
You must set the flash to off position. The AE lock cannot be set if the flash fires.
1 Focus on the part of the subject on which you wish to lock the exposure setting.
2 Press and hold the shutter button halfway and press the ISO button.
The exposure is fixed.
The * appears on the LCD monitor (or viewfinder).
3 Re-aim the camera to compose the shot as
desired and press the shutter button fully.

To Release the AE Lock:
Press any button other than the ISO button.

Well, i do just what it says and the lock is lost after ONE Shot!!!   :(
Is there something wrong with my camera??  :'(
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Offline fe50

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Re: Permanent Exposure Lock?
« Reply #6 on: 16 / August / 2008, 05:41:25 »
Hi s5-user,

after a short look to the S5 Manual: you're right, with the S5 you cant's store the AE Lock like on the Ixus series (there you can do this as described), so you have to set up Exposure manual...it's also the same with the flash (FEL)  :(

*Edit: you may save the (manual) settings in Custom mode C, but i'm not sure whether all of the needed settings can be stored there, but perhaps it may help in situations where you need constant values, e.g. in panoramas...
« Last Edit: 16 / August / 2008, 05:47:27 by fe50 »
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Offline cybercom

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Re: Permanent Exposure Lock?
« Reply #7 on: 18 / August / 2008, 23:01:24 »
@whoever:

stereoGeek I may be, but it would still be great to be able to lock exposure and focus, and then be able to zoom.

A perfect example is at a concert where the stage is lit but the audience is not. Zoom in and lock exposure/focus for the stage area and then regardless of the focal length, the stage stays properly exposed and focused instead of washing out when you zoom out to include the audience - and the camera opens up exposure to adjust for the darkness.

Or someone/something passes in front of the camera while you are zooming. Instead of the exposure varying it just stays the same because it's locked.

I can think of numerous examples where this would save the video.

(Oh! I forgot to mention that I'm mostly shooting hi-def stereo video with my four TX-1-s). 8)
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Offline whoever

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Re: Permanent Exposure Lock?
« Reply #8 on: 19 / August / 2008, 06:50:41 »
I see your point. Still, keeping constant exposure while zooming actually implies adjustments to the iris opening or shutter speed. This can be done, as ewavr suggests above. But during hi-def stereo video?! OMG... Well actually I believe ewavr knows how to adjust exposure on the fly, during video-recording. In his cam at least. So, be nice with him, and maybe one day...
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Offline dzsemx

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Re: Permanent Exposure Lock?
« Reply #9 on: 19 / August / 2008, 13:01:29 »
i use M mode for exposure lock :P
btw.. there is a function to lock/unlock AE during video recording, no?
after AF, AE is unlocked

NHSTUB(ExpCtrlTool_StopContiAE,  0xFFC24410)
NHSTUB(ExpCtrlTool_StartContiAE, 0xFFC24250)

so, what do you think?
« Last Edit: 19 / August / 2008, 13:07:42 by dzsemx »
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