Opening a can of worms - my first flash question to you guys.

Hi guys!

While I have a pretty good idea about using a camera overall, flash photography is very new to me. So far, I’ve relied on fast lenses for all my low light images. However at times like shooting on the beach facing the sun and having a subject facing the camera as well, I’ve realized that a shot like that just can’t happen without a flash to put some light in the subject’s face.

I’ve been reading a lot about using flash. I don’t feel like I’ve learned that much yet but I’m plugging along. So I wanted to use the answers of the following question as more or less first stepping stone on my way to concur flash photography.

Here’s the scenario – just like the example above, if I was to shoot a subject on the beach – me facing the sunset, her standing against the sunset and facing the camera such as the example bellow – if I’m shooting in AV the way I have been (I’m comfortable with that mode), how would I control the power of the flash?

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First of all, do not use your flash in AV mode. AV mode is usually terrible with flash unless you really know what you're doing (and if you really know what you're doing, use M) or are using the flash only as fill. Use M when using flash in a situation like you posted above. The only time you'd want to be in AV is if you're only using the flash for fill light, which is not the case in the above photo.


Set up your camera to get the exposure that you want on the background, then adjust your flash/strobe's power to get the exposure that you want on the subject that you are illuminating with the flash.

DDCSD wrote in post #8332905
First of all, do not use your flash in AV mode. AV mode is usually terrible with flash unless you really know what you're doing (and if you really know what you're doing, use M) or are using the flash only as fill. Use M when using flash in a situation like you posted above. The only time you'd want to be in AV is if you're only using the flash for fill light, which is not the case in the above photo.

Thanks Derek! How come? What does AV do to the flash that M doesn't?

DDCSD wrote in post #8332905
Set up your camera to get the exposure that you want on the background, then adjust your flash/strobe's power to get the exposure that you want on the subject that you are illuminating with the flash.

You just fire a test shot and then adjust the EFC on the actual flash separate from the camera?

There is a great deal on this method at
http://www.strobist.co​m

It is a common approach to set the camera for the background, possibly 1-2 stops down from "normal", and then set the flash to light the subject.

pixel_junkie wrote in post #8332946
Thanks Derek! How come? What does AV do to the flash that M doesn't?

AV mode will attempt to expose the ambient light. It will likely give you way to long of a shutter speed, or way too short. The shutter speed will also vary wildly depending on exactly where you point the camera.

In that situation, I would put the flash on M as well. You're in a controlled situation with a very difficult scene for the camera to meter. If the model move a hair in any direction, your camera/flash could choose wildly different settings.

CliveyBoy wrote in post #8332960
There is a great deal on this method at
http://www.strobist.co​m

It is a common approach to set the camera for the background, possibly 1-2 stops down from "normal", and then set the flash to light the subject.

Thanks! I'll eat that site for dinner tonight!

DDCSD wrote in post #8332993
In that situation, I would put the flash on M as well. You're in a controlled situation with a very difficult scene for the camera to meter. If the model move a hair in any direction, your camera/flash could choose wildly different settings.

Sounds like I've chosen an extra difficult scene as an example. What if you're in a more controlled environment? Would shooting in manual and adjusting the FEC as a secondary step not be appropriate? I'm trying to figure out not so much how to do that shot but more what the basics are when setting up any shot. Step A - set up camera in manual for proper exposure, ... step B?

One more thing - if I'm in AV, there's no way to override the Flash and control its output entirely?

the trick with AV mode and flash is to set the custom function for shutter speed with flash to maintain 1/250 of a second.

but manual is almost a necessity for a scene such as your example.

and yes Flash Exposure Lock (FEL) is very effective for that sort of scene also.
as you surmise, it separates the flash exposure calculation from the overall scene exposure calculation.

pixel_junkie wrote in post #8333029
One more thing - if I'm in AV, there's no way to override the Flash and control its output entirely?

You could, just switch your flash to Manual...

Like others mentioned keep camera in manual exposure mode. FLash can be in eTTL.

You select aperture based on dof you need. Select ss and ISO for bg ambient light. Then just use FEC for proper subject exposure.

If you need to darken bg, increase ss. If need to bring up bg, slower ss. At sunset you won't be limited by flash sync speed of the camera.

theveed wrote in post #8333114
You could, just switch your flash to Manual...

That's what I though. So if this is possible and I already know how to set up the exposure in AV well, what would I gain by using manual on the camera? If I need to underexpose the shot in AV (or overexpose, .. whatever), I can do that and then go to my flash end adjust IT to light up my subject as much as I want (by doing it manually). Would I be doing more work than necessary?

Sorry guys, not trying to be difficult, just trying to understand the advantage of Manual mode for the camera and its relation to the flash.

Av mode or Manual mode are used ONLY for the ambient light exposure.(background) In this case you need to underexpose the ambient light. This can be done with a -EV exposure compensation using Av or Manual mode.

The flash will be the main light for the subject. This can be ETTL or manual flash.
Some test shots and trail and error will be necessary.

Once you're using flash or strobes the idea is to NOT have the camera do the thinking for you, as it doesn't always make the right 'suggestion'. When you shoot in manual mode you're taking control of every aspect of the shot and the exposure. You're using shutter speed to accurately control the amount of ambient light in the shot and you're using aperture to control both depth of field and the amount of flash in your shot.

Any of the auto modes will not always give you the results you want and won't give you consistent results. Repeatability is the key to controlling light.

msowsun wrote in post #8333255
Av mode or Manual mode are used ONLY for the ambient light exposure.(background) In this case you need to underexpose the ambient light. This can be done with a -EV exposure compensation using Av or Manual mode.

The flash will be the main light for the subject. This can be ETTL or manual flash.
Some test shots and trail and error will be necessary.

Thank you sir!

TMR Design wrote in post #8333341
Once you're using flash or strobes the idea is to NOT have the camera do the thinking for you, as it doesn't always make the right 'suggestion'. When you shoot in manual mode you're taking control of every aspect of the shot and the exposure. You're using shutter speed to accurately control the amount of ambient light in the shot and you're using aperture to control both depth of field and the amount of flash in your shot.

Any of the auto modes will not always give you the results you want and won't give you consistent results. Repeatability is the key to controlling light.

Okay, thanks. Got it. So when you shoot with flash, do you set up both manually always or only your camera stays in manual?