Exposure vs flash compensation

User Profile: Newbie to Digital Photography (May be obvious by the question...)

I had a general question about exposure compensation vs flash compensation. I have Dimage 7Hi (1 week old) and been learning the various settings and results. One thing that puzzles me is the relationship between Exposure compensation and Flash compensation. I took two shots to see the difference.
1) Exp Comp 0.0 and Flash Comp +1.0.
2) Exp Comp +1.0 and Flash Comp 0.0

To me (a newbie), the shots look very close alike and I can't seem to tell the difference. Can someone explain to me when you would + - Exposure and when you might + - Flash settings?

Thanks
--
CPK

Exposure compensation: camera will under or overexpose the image by the set amount. i.e. if the camera's metering system thinks the exposure should be f/8 at 1/60s and you dial in +1 exposure compensation, it will either open the aperture a stop or halve the shutter speed (depending on other settings). You would use this when you know the camera's metering system is being fooled by the conditions -- like in a strongly backlit situation such as a person in front of a window.

Flash compensation: causes the flash unit to emit more or less flash power than the metering system would otherwise dictate. If you're taking a picture of a group of people in black suits, the camera might tend to use too much flash power, so you dial down the flash exposure compensation. Similarly, with someone dressed in all white, the metering system would tend to not emit enough flash, so you dial up the flash exposure compensation to get the proper amount.

How do you learn when to do this and how much to use? Practice and experience. Each camera's metering system is just enough different from other kinds that there's no hard and fast rules I've ever heard of. You need to learn how your equipment behaves so you know when it's likely to get "fooled" by conditions.

-- Lew

Chong said:

User Profile: Newbie to Digital Photography (May be obvious by the
question...)

I had a general question about exposure compensation vs flash
compensation. I have Dimage 7Hi (1 week old) and been learning the
various settings and results. One thing that puzzles me is the
relationship between Exposure compensation and Flash compensation.
I took two shots to see the difference.
1) Exp Comp 0.0 and Flash Comp +1.0.
2) Exp Comp +1.0 and Flash Comp 0.0

To me (a newbie), the shots look very close alike and I can't seem
to tell the difference. Can someone explain to me when you would
+ - Exposure and when you might + - Flash settings?

Thanks
--
CPK

Click to expand...

Deeddawg said:

[Snipit]

Click to expand...

Thanks,

That makes sense. As a newbie, even when testing it helps to have some general understanding and prior to you explanation, taking pictures at various Exp and Flash comp settings, I didn't know why you would make these changes - other than a shot that was just too dark or over-exposed.

Very much appreciated.

--
CPK

Follow up question. Took some shots outside under sunny conditions and did notice that the exposure was a bit dark so I "+" the exposure compensation to increase the exposure. Which yielded better results. So the question, under cloudy conditions, would you "-" the exposure? (Using reverse logic. I also realize that there are other factors but I'm just trying to get a "general" understanding. Also, I will be testing undering darker conditions.)

Thanks.
CPK

Deeddawg said:

Exposure compensation: camera will under or overexpose the image by
the set amount. i.e. if the camera's metering system thinks the
exposure should be f/8 at 1/60s and you dial in +1 exposure
compensation, it will either open the aperture a stop or halve the
shutter speed (depending on other settings). You would use this
when you know the camera's metering system is being fooled by the
conditions -- like in a strongly backlit situation such as a person
in front of a window.

Flash compensation: causes the flash unit to emit more or less
flash power than the metering system would otherwise dictate. If
you're taking a picture of a group of people in black suits, the
camera might tend to use too much flash power, so you dial down the
flash exposure compensation. Similarly, with someone dressed in
all white, the metering system would tend to not emit enough flash,
so you dial up the flash exposure compensation to get the proper
amount.

How do you learn when to do this and how much to use? Practice and
experience. Each camera's metering system is just enough different
from other kinds that there's no hard and fast rules I've ever
heard of. You need to learn how your equipment behaves so you know
when it's likely to get "fooled" by conditions.

Click to expand...

--
CPK

You probably already know the answer: "It depends."

More seriously though, the main factor you need to consider when evaluating whether to use any exposure compensation is whether the scene you are trying to photograph is one which will likely "fool" the camera's metering system. For example, if you're shooting someone standing in the shade while the background is in full sunlight, you'll often need to dial in some + exposure compensation to keep the bright background from causing the camera to underexpose your subject. (an alternative is to use fill flash to light the subject up a bit more and reduce the lighting difference between background and subject, but that's a whole other can of worms!) Of course, if the subject pretty much fills the frame (or at least fills the metering area), then the camera is less likely to be fooled.

If the subject is out in the same light as the background on an overcast day, then your camera's metering system probably won't get fooled and you'll be fine without any exp. comp.

There's no hard and fast rule for when to use exposure compensation. It all depends on the lighting, the subject, how much of the frame the subject occupies, what kind of camera you're using (different metering systems), which metering mode you're using, etc. Way too many variables to give you any sort of "rule of thumb", except to say that if the camera underexposes the image you need to go with some + compensation and if the camera overexposes you need to go the other way.

Hope this helps some.

-- Lew

Chong said:

Thanks.
CPK

Deeddawg said:

Exposure compensation: camera will under or overexpose the image by
the set amount. i.e. if the camera's metering system thinks the
exposure should be f/8 at 1/60s and you dial in +1 exposure
compensation, it will either open the aperture a stop or halve the
shutter speed (depending on other settings). You would use this
when you know the camera's metering system is being fooled by the
conditions -- like in a strongly backlit situation such as a person
in front of a window.

Flash compensation: causes the flash unit to emit more or less
flash power than the metering system would otherwise dictate. If
you're taking a picture of a group of people in black suits, the
camera might tend to use too much flash power, so you dial down the
flash exposure compensation. Similarly, with someone dressed in
all white, the metering system would tend to not emit enough flash,
so you dial up the flash exposure compensation to get the proper
amount.

How do you learn when to do this and how much to use? Practice and
experience. Each camera's metering system is just enough different
from other kinds that there's no hard and fast rules I've ever
heard of. You need to learn how your equipment behaves so you know
when it's likely to get "fooled" by conditions.

Click to expand...

--
CPK

Click to expand...

Deeddawg said:

You probably already know the answer: "It depends."

[Snipit]

Click to expand...

Thanks again. This will help with my steep learning curve. And you are absolutely right about trial and error - the only way to truly learn.

Have a great day.
Chong

Though some of your question was answered, there is more to the story.

The negative compensation on your flash is very useful when using flash outdoors. When most people use there flash outside, the just set it on TTL or Auto and it results in that overly lit 'flash' look to it when there shooting people. If your shooting on some auto camera setting, or you know what your meter reading is, dial your 'flash' (not the camera) to 'minus 1 or 2' in TTL or Auto mode. This will give you a stop or 2 less flash and just fill in the shadows a bit so the ambient light looks more natural. Wedding and portrait photographers use this technique all the time. The better ones do anyway.

Mike

To get a better feel of expsoure compensation, see if your camera has automatic exposure bracketing. I have a Nikon CP995 which does this. With digital pix, you don't have to worry about taking too many pix. Then shoot a lot of different subjects in different conditions with autoexposure bracketing and do some analysis.

Yes, my DC does have exp. bracketing. However, my primary use of the camera is for taking pictures of my kids and bracketing and kids don't go hand in hand :-o

My initial post was to get a better understand of when to + - Flash and Exp. and I appreciate everyone's feedback.

Thanks,
CPK

AMQ said:

To get a better feel of expsoure compensation, see if your camera
has automatic exposure bracketing. I have a Nikon CP995 which does
this. With digital pix, you don't have to worry about taking too
many pix. Then shoot a lot of different subjects in different
conditions with autoexposure bracketing and do some analysis.

--

Click to expand...

CPK