Additive Flash Exposure Compensation -- The benefit

I had a session yesterday with a couple and relied on the 600TTL to help with main subject lighting with bright sun.
That got me to thinking about how to combine camera Flash Exposure Compensation with light Flash Exposure Compensation.

So, today I took Manny outside and did a series of shots to illustrate the effect.

HERE is a page I added to my site detailing how it works.

There is a thing i don't understand well.

When there is an ambient light exposure compensation on Canon camera, the exposure of the main subject does not change when using flash in TTL mode.
Whatever the exposure of the background is, the exposure of Manny when "using flash with 0 EV in Canon e-TTL mode" and when "using flash -4 EC, 2 CFEC, -2 FEC, i.e. 0 NET in Canon e-TTL mode as well" would be the same if the Canon e-TTL mode works correctly.

But it's not what your photos display.
Unlike what occurs in the Canon system, your Sony - 4 EV ambient light exposure correction seemed to have had an effect on the Sony flash exposure compensation...

There from, there is imho no benefit for Canon camera users. +/- 2EV is more than enough a range in Canon e-TTL mode.

Regards,

You may be misinterpreting the two images.
The image you are referencing on the left was shot with the camera meter at 0EV. i.e. proper exposure for the scene. The image on the right has been underexposed by increasing the shutter speed from 1/400 to 1/6400 second. That's 4 EV under exposed.

With the camera FEC set to +2 and the light FEC set to -2 the net FEC is 0 which means that the flash is not adding to the exposure. You are showing a metering zone. Not sure where that came from. If its where you checked the relative exposure in Lightroom then it should show something close to -4EV difference.

David you're making my head hurt. I have to ask why and what benefit would I have, even if I could but, I can't since I am a Canon shooter. Why would I want to have a setting of +3 FECC and -2FECL for a net of +1 FEC when all I have to do is add +1 FEC to my transmitter?

Of course as a Canon shooter any FEC entered into an "on camera" flash or a transmitter over rides any FEC set in the camera so it is not additive. In fact I wished Canon would just eliminate entirely the cameras FEC or at least remove the cameras FEC from the ISO quick button, on the top of the camera, so that I do not keep accidentally entering an FEC when trying to change ISO settings. I never use the cameras FEC anyway so I guess I will never own the Profoto B1's.

I have read and reread your article but I keep getting side tracked by the -6 EC. Which brings me back around to my original question, why and what is the benefit of this for someone when using TTL? I am not sure how to use the information, even if I could, and I am really not seeing any benefits.

dmward wrote in post #18025296
You may be misinterpreting the two images.
The image you are referencing on the left was shot with the camera meter at 0EV. i.e. proper exposure for the scene. The image on the right has been underexposed by increasing the shutter speed from 1/400 to 1/6400 second. That's 4 EV under exposed.

With the camera FEC set to +2 and the light FEC set to -2 the net FEC is 0 which means that the flash is not adding to the exposure. You are showing a metering zone. Not sure where that came from. If its where you checked the relative exposure in Lightroom then it should show something close to -4EV difference.

What i realize when reading your review and what i want to share is Canon cameras and Sony cameras don't work the same. Your review is very helpful for Sony camera users but it may confuse/mislead Canon camera users.

When EC is set to zero, does the ambient light add to the exposure or not ? It does, of course. With zero exposure compensation according to camera ambient light told exposure.
With the camera FEC set to +2 and the flash FEC set to -2 the net FEC is 0 NET which means the flash is adding to the exposure in TTL mode with zero flash exposure compensation. But it does.
With the camera FEC set to +2 and the flash FEC set to +2 the net FEC is 4 NET which means the flash is adding to the exposure in TTL mode with +4EV flash exposure compensation.

When EC is set to -4 EV onto Sony camera, the Sony ambient light exposure compensation underexposes also the Sony TTL flash exposure in the same way : by -4EV.
When EC is set to -4 EV onto Sony camera, the camera FEC set to +2 and the flash FEC set to +2, the net FEC is 4 NET. And this FEC 4 NET neutralises the -4EV Sony TTL flash exposure due to -4EV Sony ambient light exposure compensation. There from, the exposure of manny 0 EC, flash 0 EV in Sony TTL mode is the same than the exposure of manny -4 EC, +2 CFEC, + 2 FEC, 4 NET in Sony TTL mode (when exposure of the background changes).

When EC is set to -4EV onto Canon camera, the Canon ambient light exposure compensation has no effect at all on the Canon e-TTL flash exposure : the Canon e-TTL flash exposure remains the same (when the same flash metering zone is used ; it's why i added a same theorical flash metering zone on Manny's face), it's not reduced by - 4EV. As it's not reduced by -4EV, Canon camera users don't need additive +5/+6 FEC. They need at most +1/+2 EV flash exposure compensation. Additive FEC is no benefit for Canon camera users.

agv8or wrote in post #18025572
... Of course as a Canon shooter any FEC entered into an "on camera" flash or a transmitter over rides any FEC set in the camera so it is not additive. ...

Rand, that's what I couldn't remember from shooting Canon. Maybe that's why I'm impressed with the additive capability with the Sony A7RII.

The benefit is the expansion to +/- 6 EV of exposure compensation. It means that one can dramatically underexpose the ambient (usually bright outdoor scene) and properly expose the subject via the flash.

From time-to-time there appear threads, which turn into debates, about whether to use ND filters or HSS to "over power" the sun. The additive capability with FEC on the Sony makes it possible to control the substantial spread. i.e. turning day into night.

Not something that one will use everyday. Maybe not even once a month, but useful tool when needed.

Pictoraider wrote in post #18025624
What i realize when reading your review and what i want to share is Canon cameras and Sony cameras don't work the same. Your review is very helpful for Sony camera users but it may confuse/mislead Canon camera users.

When EC is set to zero, does the ambient light add to the exposure or not ? It does, of course. With zero exposure compensation according to camera ambient light told exposure.
With the camera FEC set to +2 and the flash FEC set to -2 the net FEC is 0 NET which means the flash is adding to the exposure in TTL mode with zero flash exposure compensation. But it does.
With the camera FEC set to +2 and the flash FEC set to +2 the net FEC is 4 NET which means the flash is adding to the exposure in TTL mode with +4EV flash exposure compensation.

When EC is set to -4 EV onto Sony camera, the Sony ambient light exposure compensation underexposes also the Sony TTL flash exposure in the same way : by -4EV.
When EC is set to -4 EV onto Sony camera, the camera FEC set to +2 and the flash FEC set to +2, the net FEC is 4 NET. And this FEC 4 NET neutralises the -4EV Sony TTL flash exposure due to -4EV Sony ambient light exposure compensation. There from, the exposure of manny 0 EC, flash 0 EV in Sony TTL mode is the same than the exposure of manny -4 EC, +2 CFEC, + 2 FEC, 4 NET in Sony TTL mode (when exposure of the background changes).

When EC is set to -4EV onto Canon camera, the Canon ambient light exposure compensation has no effect at all on the Canon e-TTL flash exposure : the Canon e-TTL flash exposure remains the same (when the same flash metering zone is used ; it's why i added a same theorical flash metering zone on Manny's face), it's not reduced by - 4EV. As it's not reduced by -4EV, Canon camera users don't need additive +5/+6 FEC. They need at most +1/+2 EV flash exposure compensation. Additive FEC is no benefit for Canon camera users.

The Sony A7RII has a menu option where the photographer can select whether exposure compensation applied to ambient or both ambient and flash. To realize the benefit of the additive Flash Exposure Compensation capabilities the setting should be ambient. I think I mention that, I'll have to confirm.

Exposure compensation is set via the dial on the camera and Flash Exposure Compensation is set via a menu option.

dmward wrote in post #18025735
The Sony A7RII has a menu option where the photographer can select whether exposure compensation applied to ambient or both ambient and flash. To realize the benefit of the additive Flash Exposure Compensation capabilities the setting should be ambient. I think I mention that, I'll have to confirm.

I did not know about Sony A7RII such capabilities. Thanks for sharing.
It seems your article's photos have been taken with exposure compensation applied to both ambient and flash.

Pictoraider wrote in post #18025767
I did not know about Sony A7RII such capabilities. Thanks for sharing.
It seems your article's photos have been taken with exposure compensation applied to both ambient and flash.

For this exercise I used manual exposure settings. The camera calculated an exposure of 1/400, f2.8, ISO 100. I set the shutter to 1/6400 to get a -4EV exposure for ambient. Then used FEC settings to control the exposure from the strobe. I chose this approach because the A7RII only offers -3 EV exposure compensation via the dial on the camera.

I chose this approach, as I mentioned when replying to Rand, because there is so much talk about how to use strobes in combination with underexposed ambient settings to over power the sun.

For fast moving event photography I do more often use Av shutter mode and then use Exposure Compensation along with Flash Exposure Compensation to get the results I want. That's much less about over powering the sun and more about getting a well balanced exposure with the strobe as fill or main light in the shade.

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