Difference between 2 features - General Discussion and Assistance - CHDK Forum

Difference between 2 features

  • 3 Replies
  • 1122 Views
Difference between 2 features
« on: 26 / January / 2014, 13:27:33 »
Advertisements
Hello :)
Could you please tell me the difference between "Auto Flash + Exp. Comp" and "Manual Flash + Power". As far as I understand the first option chooses a optimal power,or you can enter a specific power for the flash. The second seem to give you the option to choose a specific power for the flash output.
So what is difference ? :\

Re: Difference between 2 features
« Reply #1 on: 26 / January / 2014, 13:37:53 »
Auto Flash + Exp. Comp   :  allows exposure compensation (in 1/3 eV units) when using the camera's build-in flash power control.
Manual Flash + Power : brute force override of the flash output power - not affected by actual exposure requirement of the camera.

See
    http://chdk.wikia.com/wiki/CHDK_1.2.0_User_Manual#Auto_Flash_.2B_Exp._Comp.
and 
    http://chdk.wikia.com/wiki/CHDK_1.2.0_User_Manual#Manual_Flash_.2B_Power

and the discussion here :
http://chdk.setepontos.com/index.php?topic=10263.0
« Last Edit: 26 / January / 2014, 13:40:41 by waterwingz »
Ported :   A1200    SD940   G10    Powershot N    G16

Re: Difference between 2 features
« Reply #2 on: 26 / January / 2014, 13:58:09 »
Thanks,it makes sense
One more question. At the "Auto Flash + Exp. Comp." option, to get auto flash exposure should I let the first parameter unchecked,or should I check it and set the second parameter to 0 ?

*

Offline philmoz

  • *****
  • 3107
    • Photos
Re: Difference between 2 features
« Reply #3 on: 26 / January / 2014, 17:10:06 »
Thanks,it makes sense
One more question. At the "Auto Flash + Exp. Comp." option, to get auto flash exposure should I let the first parameter unchecked,or should I check it and set the second parameter to 0 ?

The default on Canon cameras is to use ETTL metering for the flash.
The camera measures the amount of light from the flash and turns off the flash when it thinks the exposure is correct.

Some cameras allow you to set the flash to Auto (ETTL) or Manual, and in Auto mode to set the flash exposure compensation (which affects how the flash exposure is calculated). In manual flash mode you can set one of three power levels (min, med, max).

Other cameras give you no control over the flash, other than to turn it on or off.

Finally on cameras that have a manual (M) shooting mode, Canon forces the flash to manual mode and only allows you to set one of three power levels.

The CHDK flash overrides give you the same controls as the above Canon functions, auto with flash exposure compensation, or manual with three power levels.

You can use the CHDK 'Auto Flash + Exp Comp' override in the following cases:
- your camera does not have built in settings for flash exposure compensation and you want to adjust the flash power; but still use ETTL metering overall
- you want to enable ETTL flash in M mode

Unless you are shooting in M mode, then enabling 'Auto Flash + Exp Comp' with 0 compensation is equivalent to the default Canon flash settings - the two options you presented should produce equivalent results.

Phil.
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)


 

Related Topics