exposure meter & flashgun

[hamlet]

I am trying to figure out how to get my exposure meter to the little 0 in the middle when using my camera with a external flashgun attached? My flashgun and camera are on i-ttl and the exposure meter tells me that my picture will be severely underexposed. Is it supposed to be like this? Isn't i-ttl supposed to calculate the light from your flashgun as well?

 

[Overread]

No.

The cameras built in meter can only read ambient light in the scene itself. Thus only constant light can be read by it.

The various through the lens methods work by the flash sending out a light pulse in a split second when the camera shutter is pressed (normally its too fast to see). The camera reads the light through the lens from that flash and sends that data up to the flash; the flash then adjusts its power to try and give a good exposure for the scene based upon the camera settings and how the light affected the scene - the flash then sends out its primary light burst (all in that split second).

Note that as a result the flash varies its power automatically rather than the camera changing its settings.

 

[hamlet]

thank you, that was pretty concise.

 

[Overread]

Glad it helped- note that this explains why there is exposure compensation and flash exposure compensation (because the ttl might not be 100% accurate so sometimes you' have to learn to dial it back a little from what it thinks should be used - esp if using it for fill lighting on a bright day).

 

[hamlet]

Yes, i noticed it was a function in my flash.

Concerning hss though: if i use hss with my camera, is the flashgun more limited in the amount of light it can produce? I started another thread about hss, but i cant remember how that exactly worked.

 

[Overread]

Watch the video - it will give you a good all round answer to that question .

 

[hamlet]

That video explains it pretty well, now its all coming back to me.


flash photography is pretty fun.

 

[KmH]

The sensor that the camera uses to read the reflected light from the extremely short duration of TTL pre-flashes is the same sensor that is used to display the still shot exposure in the viewfinder.
However, the display lacks the capability to record and show the exposure value from the extremely short duration of the pre-flash(s) flash exposure value in a time frame humans can perceive.
Put another way, the in-the-camera light meter can only display the exposure value of reflected light as it applies to non-flash still photos.

There are hand held light meters that can record and show the exposure value of light from flash units, incident light, and reflected light.
Flash and incident light values are measured by facing the hand held meter towards the light source from the point the photographer wants to measure the light.
That is usually very close to the subject and/or background/foreground elements.
Reflected light is measured with a hand held light meter by facing the light meter towards the subject or background/foreground elements.