eTTL in manual mode Issue - page 2 - Script Writing - CHDK Forum
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eTTL in manual mode Issue

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Offline waterwingz

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Re: eTTL in manual mode Issue
« Reply #10 on: 27 / June / 2013, 10:33:47 »
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Quote from: philmoz on 27 / June / 2013, 08:25:58
So far I can't get the exposure compensation to work for an external flash though.
Does that mean the external flash TTL works and adjusts the exposure with  TV, Av, Sv locked in manual but you just can't adjust/offset/compensate the exposure?
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Offline jim2386

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Re: eTTL in manual mode Issue
« Reply #11 on: 27 / June / 2013, 13:36:03 »
Mr. Water (or perhaps Mr. Wingz? :) )

I talked to my brother, the guru of all things canon camera and he informed me what I may be experiencing is the "safety shift" feature.

Normally, safety shift is turned off in manual mode since, well, it's supposed to be manual. However, it appears that through this ettl script, safety shift is turned on.

You probably already know about it, but just in case I'll explain.  Basically it appears canon cameras have a feature called "safety shift" that, when active, tries to prevent over and under exposure. If I pick a shutter speed and aperture in M mode and the camera sees that the picture is set up for underexposure, it will override my settings to try to get proper exposure.

Again, in a standard-no-CHDK-active-camera-in-M-mode, safety shift is deactivated by default so it doesn't try to override to prevent over or under exposure. However, it appears activating TTL turns on safety shift which is what very well could be causing my issues.

Does anyone in the CHDK community know A. is there a manual turn off for safety shift in the normal canon menus?  B. Is there a safety shift deactivate in the CHDK menus and/or C. Is there known script code that can be added to my script to deactivated safety shift when I run my eTTL script?

I hope this helps diagnose the issue. If this can be corrected, this would be an awesome feature to add to the CHDK main menu. I guarantee a lot of people could use it.

Thanks
Jim
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Offline jim2386

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Re: eTTL in manual mode Issue
« Reply #12 on: 27 / June / 2013, 13:39:29 »
Phil,

Basically all I want is all the features of M mode with the strobe changed from Manual to Auto (or eTTL if you will). See my previous post about safety shift being enabled when auto flash is enabled. Sounds like I need the strobe changed to auto and ensure that safety shift is OFF always in M mode. That would be exactly what I'm looking for and would make you a God amongst mere mortals and a hero in my eyes :)

Thanks!
Jim
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Offline jim2386

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Re: eTTL in manual mode Issue
« Reply #13 on: 27 / June / 2013, 15:35:13 »
Update with possibly more useful information:

I am talking with a fellow diver who wrote eTTL in M script. I asked him about the safety shift or the shutter and aperture not staying locked when I do a half shutter press. This is how he responded:

There is no property case in CHDK to modify the safety shift. I have it OFF on my S95 and I do not experience any of the issues you mentioned. If I put it to ON the behaviour does not change and the script still works as expected.
I now recall I did have this problem at some point in time but I resolved it upgrading CHDK and not changing the script. Since then I have kept the same build of CHDK and had no issues.
After that I have had reports from other users of DIGIC V based cameras (S100/S110/G12) that experience your issue.
So it is not a case of modifying the script as the property case is the same but of having a version of CHDK that works properly

His code is as follows:

@title TTL ON OFF
rem Author: Interceptor121


rem Turn on or off TTL flash
rem with mode dial in 'Manual' for which the factory firmware doesn't support TTL.
rem The script should be run manually using the ALT+Shutter combination


rem Script is based on the example of jamesinsummer from:
rem G Series TTL In Manual Mode
rem DIGIC4 Flash Power id:121 0:auto 1:Manual

rem parameters for Flash exposure compensation id:127
@param a Flash Comp (Ev)
@default a 0

rem b=before
rem c=current

rem check status of dial more
get_prop 49 m

rem if the camera is not in manual or custom then exit
if m <> -32767 then
 exit_alt
endif

get_prop 121 b


if b=0 then
 set_prop 121 1
else
  set_prop 121 0
endif


get_prop 121 c

rem status reporting
if c=b then
 print "ERROR: Flash Off"

else

 if c=0 then
  a=a*32
  get_prop 127 P
  print "Old Fec:",P
  set_prop 127 a
  print "New Fec:",a
  print "TTL ON"
 else
  print "TTL OFF"
 endif

endif

exit_alt
end



Is there any reason why CHDK on digicV wouldn't work the same as on Digic4? Just trying to offer as much information on the request/issue as possible.

Thanks
Jim
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Offline philmoz

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Re: eTTL in manual mode Issue
« Reply #14 on: 27 / June / 2013, 18:51:39 »
Quote from: waterwingz on 27 / June / 2013, 10:33:47
Quote from: philmoz on 27 / June / 2013, 08:25:58
So far I can't get the exposure compensation to work for an external flash though.
Does that mean the external flash TTL works and adjusts the exposure with  TV, Av, Sv locked in manual but you just can't adjust/offset/compensate the exposure?

Yes.
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Offline philmoz

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Re: eTTL in manual mode Issue
« Reply #15 on: 27 / June / 2013, 18:52:53 »
Quote from: jim2386 on 27 / June / 2013, 13:39:29
Phil,

Basically all I want is all the features of M mode with the strobe changed from Manual to Auto (or eTTL if you will). See my previous post about safety shift being enabled when auto flash is enabled. Sounds like I need the strobe changed to auto and ensure that safety shift is OFF always in M mode. That would be exactly what I'm looking for and would make you a God amongst mere mortals and a hero in my eyes :)

Thanks!
Jim

I'll have a play with it some more over the weekend.
If you want to send me a PM with an email address I can send you test builds to try out.

Phil.
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CHDK ports:
  sx30is (1.00c, 1.00h, 1.00l, 1.00n & 1.00p)
  g12 (1.00c, 1.00e, 1.00f & 1.00g)
  sx130is (1.01d & 1.01f)
  ixus310hs (1.00a & 1.01a)
  sx40hs (1.00d, 1.00g & 1.00i)
  g1x (1.00e, 1.00f & 1.00g)
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Offline philmoz

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Re: eTTL in manual mode Issue
« Reply #16 on: 29 / June / 2013, 07:42:30 »
I've added the code to set the flash to Auto and set flash exposure compensation to the trunk in revision 2907.

It allows the flash to work in ETTL mode when the camera is in M mode.

Exposure compensation will only work for propset 4 & 5 cameras - it needs a new propcase value for the others.

This has been tested, and mostly works, on the G12, G1X, & SX40 (by me) and the G15 by Jim.

Notes:
 - on the G12 it will occasionally choose a shutter speed that is 1/3 stop faster than the one dialled in on the camera.
 - on the G1X it almost always chooses a shutter speed 1/3 stop faster.
 - flash exposure compensation works for the built in flash; but not when using an external flash.
 - you have to turn the flash on with the Canon menu (or raise the flash if needed).

I've added a new menu option to force Auto flash and renamed the old one to indicate it is for Manual flash.

I'd be interested to see how it behaves on other cameras.

Phil.

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CHDK ports:
  sx30is (1.00c, 1.00h, 1.00l, 1.00n & 1.00p)
  g12 (1.00c, 1.00e, 1.00f & 1.00g)
  sx130is (1.01d & 1.01f)
  ixus310hs (1.00a & 1.01a)
  sx40hs (1.00d, 1.00g & 1.00i)
  g1x (1.00e, 1.00f & 1.00g)
  g5x (1.00c, 1.01a, 1.01b)
  g7x2 (1.01a, 1.01b, 1.10b)
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Offline waterwingz

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Re: eTTL in manual mode Issue
« Reply #17 on: 29 / June / 2013, 09:59:29 »
Quote from: philmoz on 29 / June / 2013, 07:42:30
I've added a new menu option to force Auto flash and renamed the old one to indicate it is for Manual flash.
Sure,  I just knew this would happen.  Changes to the only part of the new user manual that I actually have completed :  http://chdk.wikia.com/wiki/CHDK_1.2.0_User_Manual#Enhanced_Photo_Operations   :'(

How do I describe what this does in the docs - its not clear exactly what was done compared to the script the OP was trying to use originally ?  "Selecting this enables internal/external automatic eTTL exposure control with compensation when the rest of the  camera settings are is in M mode. " ?
« Last Edit: 29 / June / 2013, 10:08:52 by waterwingz »
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