Neil, this is far the best resoure for flash fhotography I found in the Web. Thanks for that.
Carlos.

Adi .. your questions are thoroughly answered in this article on balancing flash with ambient light.

Neil vN

Hi there Uli ..

You are completely correct – all three controls do and will affect ambient exposure, regardless of whether flash is used, or not; and whether the flash is TTL or manual.

It is implied there with the statement that shutter speed is the only independent control for ambient light. But it is more thoroughly explained in the main article on dragging the shutter.

thanks

Neil vN

lots of great and extremely helpful advice!

Maybe you should mention that changing the shutter speed isn’t the only way to control ambient light when using manual flash either. You can also choose a higher ISO setting and/or a different aperture in order to avoid slow shutter speeds and still get a correct flash exposure by reducing the flash power (or changing the distance between the flash and the subject, but that would require off-camera flash, and the quality of the light would change, too). Of course this is way more complicated than using TTL flash, but it does work. Probably the biggest difference is that this way you have to do all the thinking yourself instead of relying on the camera and/or flash software.

Frankee .. with TTL flash, the tonality (ie, whether the subject / scene is predominantly darker toned or lighter toned), will most definitely influence the exposure.

The same thing that makes TTL flash so easy to use and fast to use and flexible to implement, also makes it inconsistent. But that is something we expect, and we either compensate for it during the shoot (preferable), or adjust for it in post-production (preferably not) … or we use manual flash.

Neil vN

I am shocked and thrilled that you answered my question. Thank you.
Another one comes to mind. This one is prompted by the varying results I sometimes get while “dragging the shutter”. Some shots, perfect exposure, some blown out.
I have a Canon 550EX.
Since the flash appears to be making some decisions, would it not produce a bigger “pop” for a group wearing all black outfits as opposed to a group wearing all white outfits?

Frankee

Anoop, I rarely shoot anything other than manual exposure mode, so I wouldn’t use overall exposure compensation like that.

As for the specific example you ask about, it sounds Nikon-centric since you are talking about using overall exposure compensation for the ambient exposure, and FEC for flash. Yes, in theory, using EC and FEC like that should cancel each other out .. but you do create problems for yourself in having your ambient exposure AND your flash exposure at the mercy of the camera’s metering system and how it interprets the scene and subject.

The solution? As always .. shoot in manual exposure mode on your camera. And then use either TTL flash (which you control with FEC), or use manual flash.

Neil vN

Frankee .. I assume you’re talking about TTL flash here. (Manual flash wouldn’t vary at all, while aperture, ISO and distance remain the same.)

The two main camera systems each have a different way of approaching this. They appear to work similarly.

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With Nikon, you have TTL / TTL BL flash metering for TTL flash.
This is set on the speedlight.

The way I understand this to work (and I’ll gladly be corrected or fine-tuned on this), is that with TTL BL flash metering, the camera takes the ambient light into account when calculating the flash exposure.

With TTL flash metering, the flash metering would appear to be uncoupled from the ambient metering.

So, as far as I understand this, in theory, the flash should produce the same ‘pop’ .. ie, the same amount of light (and same exposure), even if you changed the shutter speed to allow more ambient light in.

With TTL BL, (as far as I understand it), the camera takes the change in ambient light into account when figuring out how much flash to emit. So, it would seem that the flash would give more or less exposure as you changed the ambient light.

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With Canon, you have Average / Evaluative flash metering for TTL flash.
This is set on the camera body via the custom functions.

The way I understand this to work (and once again I’ll gladly be corrected or fine-tuned on this), is that with Evaluative TTL flash metering, the camera takes the ambient light into account. And with Average TTL flash metering, the camera is less biased by the available light.

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In the end, I work in a fairly simplistic way.
With Nikon I keep it to TTL BL, and with Canon I mostly keep it to Evaluative TTL flash metering.

Then I adjust my flash exposure compensation to taste. I do this by pre-judging the tonality of my subject and scene, and making an educated guess as to how much FEC I would need. And then I fine-tune this by looking at the image on the camera’s preview.

Ultimately you HAVE to get used to how your camera and flash responds, by getting familiar with your equipment and shooting a lot.

Neil vN