canon eos 300d + YN568EX II: great results but unsure why

romalfox wrote:

Hi team,

it was a bit of a guess this mix of a new style flash and a 10+ year old camera, but they work great togheter.

Here goes my question.

In Tv mode and HSS enabled on the flash, the result of the pictures is okay, but I'm unsure why because when composing the picture, I can see in my viewfinder the shutter speed being (e.g.) 1000 and my exposure indicates (e.g.) 4.0 with ISO 200, and my exposure is blinking indicating underexposure.

So to me this means that TTL is warning me that the picture would be underexposed, but in fact, they are not.

They are not because indeed the flash kicks in and makes me a nice picture.

But my question is, how can I be sure this works all the time ? Why is the aperture blinking as if no flash is mounted ?

Even if I use FEL, it gives me the same behaviour: blinking aperture reading but okay pictures.

Any clue where I miss something ?

best regards,

Raf

In Tv, Av, and M the in-viewfinder meter is giving the relative exposure for the ambient light level without regard to the light the speedlite provides. This is to provide balanced fill-flash: shutter/aperture/iso set for the ambient light and the flash provides proper exposure of your near subject. The amount of flash power given by the speedlite is determined separately via the ETTL metering (and the meter scale for Flash Exposure Compensation - FEC), and so will provide the proper amount to expose your near subject (provided it has enough power for the subject distance, ISO, and aperture)

Tv and Av are autoexposure modes and try to get the proper ambient light exposure. Av can automatically adjust the shutter speed over a very wide range (down to 30 sec.) so can almost always get the ambient exposure right regardless of the aperture set. On the other hand Tv mode has a very limited range of apertures available (varies by lens, typ. To get the proper ambient light exposure for a shutter speed of 1/1000 might require an aperture wider than the lens is capable, so Tv will set the lens wide open and blink the aperture reading to let you know it's not enough for the background. The flash gives good exposure to your near subject, but the background will be underexposed.