flash compensation?

[ahbeng]

whats the difference between flash compensation on flash and on camera itself? for taking normal indoor photos, which do i dial?

 

[jasonpgc]

whats the difference between flash compensation on flash and on camera itself? for taking normal indoor photos, which do i dial?

Exposure Compensation=

Dial this to override the exposure for ambient light if you're in Auto Mode ( AV, TV, P)


Flash Exposure Compensation=

Dial this to override the flash power emitted if you're using TTL Auto Mode. (ATTL, ETTL)

If you're taking a NORMAL indoor picture, you don't have to dial any of them :bsmilie:

 

[ahbeng]

thanks but my question is difference between
1) flash compensation "on flash" and
2) flash compensation "on camera"

 

[mpenza]

it's the same. on Nikon system, the effect is addictive if I'm not wrong.

 

[Zerstorer]

it's the same. on Nikon system, the effect is addictive if I'm not wrong.

You bet it is! Once I start adding I dunno when to stop... ;p

On a more serious note, EV compensation will affect the overall exposure and more importantly the ambient exposure.

Flash compensation directly the flash exposure, unless the flash is the main light source.

The 2 controls are independent.

 

[jasonpgc]

thanks but my question is difference between
1) flash compensation "on flash" and
2) flash compensation "on camera"

Sorry, see wrongly.

There is No Different.

I think Canon have FEC(Flash Exposure) because previously their Consumer Class Flash like 380EX do not come with any manual Flash control. Therefore the EOS 50 Class and above have a FEC function to alter the flash Power.

Alternatively, some third party external Flash have ISO settings on the flash for both manual and auto mode. Therefore, if you use it on a camera body without FEC, For example the Rebel Class, you can set the Flash to Auto and adjust the ISO setting to offset the flash power.

 

[ahbeng]

i suppose the flash overrides the cam??

 

[jasonpgc]

i suppose the flash overrides the cam??

I don't know, but I also think the effect should be additive.

Here's my logic,

If the Camera AI think it should fire at Full Power Flash,

If you've set the Camera FEC to -1 stop, it would send a request to the flash unit to fire at a power same as (Full Power - 1 stop) when you press the shutter.

If the flash's own compensation is set to -1 stop. It would reduce one stop power from the value requested by the camera.

Which means that the flash now will be firing at ((Full Power -1 Stop) -1 Stop) = Full Power - 2 Stop.

Someone please correct me if my deduction were wrong. :dunno:

 

[Bean]

Just tried it on D100 and a SB80DX, from the images, seems like the result is additive...

Anyone can confirm by doing a test as well?

My question now is whether is this the same for all Nikon bodies and flashes? :dunno:

 

[mpenza]

it's additive for all nikon bodies according to Thom Hagon's book on Nikon flashes.

 

[chriszzz]

I don't know, but I also think the effect should be additive.

For the previous Canon flash system ( ie the ATTL EZ flash systems on EOS 5, 10, etc systems ), the flash overrides the camera. In other words, it is NOT additive. It would be quite logical for Canon to continue this behavior in the ETTL EX flashses, but I don't know for sure since I don't have a 550EX to test it with.