Nagging question...

On beforehalf, I'll apologize for this topic, because it isn't really to any use, Its
more to spark your interest

More and more I'm starting to see the possibilities of TTL shooting, Ofcourse, these
are more expensive then manual flashes, I first thought, why should the flash do the math,
If you got a bunch of processors in the body itself, Why not tell the camera what power
setting the flash is on, and let the camera itself do the math.

Wouldn't it be possible to through lets say a firmware update (custom) to make this
a possibility ?

And again, sorry if this is useless and I wasted a minute of your life

Odin van Oord

In ETTL the camera is doing the math and telling the flash what to do.

TTL - Through The Lens

A canon body already tells the flash how to.

When a canon flash is connected to a canon camera
- the camera tells the flash when to fire and when to stop
No need for a firmware update

Odin, I think that you might have been misled a bit about this. You mention that (E)TTL flashes (E is for "effective" because that is what digital cameras have since it is different from the original TTL developed for film, yet I digress...) you mention the flashes being more expensive and it seems you thought this expense is because the flashes are doing the "thinking". But as the previous posts explained the camera is doing the thinking - so why are the flashes more expensive? The flashes need to be able to communicate with or at least understand and use the information the camera sends. I presume this is where the extra expense comes in as compared to a manual flash.

kfyount wrote in post #11796689
Odin, I think that you might have been misled a bit about this. You mention that (E)TTL flashes (E is for "effective" because that is what digital cameras have since it is different from the original TTL developed for film, yet I digress...) you mention the flashes being more expensive and it seems you thought this expense is because the flashes are doing the "thinking". But as the previous posts explained the camera is doing the thinking - so why are the flashes more expensive? The flashes need to be able to communicate with or at least understand and use the information the camera sends. I presume this is where the extra expense comes in as compared to a manual flash.

The E is for evaluative, not effective.

gonzogolf wrote in post #11796701
The E is for evaluative, not effective.

I thought it was for "Expensive".

PacAce wrote in post #11796731
I thought it was for "Expensive".

Exasperating....

Estimatation

All ETTL flashes need to be able to (do these things that no manual flash does)...

• adjust their zoom head settings according to the information which comes from the camera
  
• change the information sent to the body about the head vertical angle
  
• respond to commands to provide AF assist light
  
• respond to commands to send out preflash
  
• respond to commands to go into HSS mode suited to the shutter speed in use
  
• respond to commands to go into stroboscopic mode
  
• respond to commands to use FEC values
  
• respond to second curtain sync commands
  

gonzogolf wrote in post #11796701
The E is for evaluative, not effective.

Oops - I knew that (just typed the wrong "e" word). Since the TTL system in a digital camera can't read the light reflecting from the film in real time, it "evaluates" the ambient light compared to the preflash and uses that information to control the flash.

PacAce wrote in post #11796731
I thought it was for "Expensive".

I've also seen where people think it is "electronic"

Eew, I knew that (A), my main point was, the camera has to transmit to the flash, but what if you
could specify to the camera what flash/power is transmitted, and make (instead of changing flash
power, I beleive they do) the camera change its shutterspeed/aperture.

Odin

sorry for my completely vague and incorrect story xD

OdinvO wrote in post #11800667
....but what if you
could specify to the camera what flash/power is transmitted, and make (instead of changing flash power, I beleive they do) the camera change its shutterspeed/aperture.

That would be very impractical, if not impossible, as the analysis for the exposure would be after the main flash burst was emitted. There simply would not be time for the camera to do the calculations and then physically change the aperture (shutter speed doesn't affect flash exposures) before recording the image.

OdinvO wrote in post #11800667
Eew, I knew that (A), my main point was, the camera has to transmit to the flash, but what if you
could specify to the camera what flash/power is transmitted, and make (instead of changing flash
power, I beleive they do) the camera change its shutterspeed/aperture.

Odin

sorry for my completely vague and incorrect story xD

Given that aperture and shutter speed play a fairly significant role in the outcome of the shot (DOF, Ambient balance) I'm not sure why you would want to make those subservient to flash power as your primary factor in exposure. The closest you could get is the External Flash Metering mode on the 580EXII where the flash measures its own(relfected) output and shuts off after enough light is measured to make a proper exposure. This emulates the old auto thyristor flashes like the vivitar 285.

Thanks for all the responses, I had a feeling it wouldn't work, but now I know why, thanks

Odin