FEC

[Matt30D]

I have a NOOB question....I understand how aperture has a huge impact on how bright the scene is with flash, but I am a little confues on FEC. Lets say I am taking a picture of a bunch of groomsmen in front to a nice brick building, and I fire the flash and take the shot (F-8 200 ISO 1/160th) It seems like I lose a lot of the detail in the guys' suits....would FEC help this, or would I close down the aperture to let more ambient in??? Any ideas?? I am using a 5D and the sync is up to 1/200th....Should I

[ZSutton]

Detail? as in the detail is blown out? Are you underexposing maybe? We will probably need to see some pictures

Also, closing down the aperture will just make you lose more ambient, you'd want to open the aperture to get more natural light, but overall, shutter speed will be the main contributor to ambient lighting

[brecklundin]

did you visit Planet Neil and see this page, which I think applies to your question?

http://www.planetneil.com/tangents/exposure-metering/exposure-compensation/

ahhh, piffle!! I re-read it and it's not talking about FEC but camera compensation.

EDIT: ahhhh, here was the page I found there:
http://www.planetneil.com/tangents/flash-photography-techniques/8-flash-exposure-comp/

[brecklundin]

Being new to flash myself, I thought through and I think I remember the basic concept now.

First meter on the subject being over exposed, dial in your FEC, then meter off your actual subject and adjust your camera settings to get the exposure correct. Or maybe it's the other way 'round?

EDIT: Oh, skrew-it...that doesn't seem to work either. Even with FEC set to -2 I still have to adjust the camera's exposure to a -2 to get a proper exposure with ETTL and FEC set to -2...so, heck, I'll just sit back wait forthe correct answer while comtemplating I haven't learned squat so far...sigh!! ;)

[gonzogolf]

FEC is adjusting the power of the flash to match the aperture you have already picked, using whatever mode you have the camera in. Check your histogram to see if your clipping on either end. Then use FEC to correct the exposure.

[Titus213]

Actually FEC is adjusting the flash outside the 'normal' exposure the ETTL system would come up with if left on its own. ETTL says I need this much flash. FEC says add or reduce that much flash from what ETTL wants.

[egordon99]

Titus pretty much nailed it. You're shooting at ISO100, f/8 and the camera's metering system (after sending out it's pre-flash) determines that the flash needs to fire at 1/8 power for "proper" exposure. You take the picture, and it's a bit underexposed, so you dial in +1 FEC. The flash will now fire at 1/4 power. Likewise, dialing in -1 FEC forces the flash to fire at 1/16 power.

My one big complaint is that the flash power used for a particular shot is NOT stored anywhere, so it can be kind of tough to figure out what's going on "under the hood"....

[egordon99]

This might help - Just replace P-TTL with E-TTL, and 1/180s with the proper X-sync speed of your body -

Basically, with flash, the FLASH exposure is solely determined by flash power (actually duration, how long the bulb is actually firing for), aperture and ISO. Ambient exposure is determined by ISO, shutter speed, and aperture (just like without any flash), so the trick is balancing the two. If I'm indoors in a smallish room (such as in someone's house), I usually just forget about ambient since the flash is powerful enough to light up the entire room (hence the 1/180s below, if the flash didn't fire, I'd have a more or less black picture) Now although you're shooting MANUAL Mode, that's only for the ambient exposure (the exposure needle in the viewfinder will blink warning you about underexposure, but ignore that). The camera's P-TTL metering will determine the needed flash output for a proper exposure.

Here's something I wrote on another forum -
"Easy" recipe for great P-TTL flash shots -
1)Point flash at ceiling
2)Put camera in MANUAL mode on the mode dial
3)Set FEC to +1 on the flash head

4)Shoot RAW (this allows you to recover some highlights that might get blown as a result of #3 above)

5)Set ISO to 200 (to start)
6)Set shutter speed to 1/180s
7)Set f-stop to whatever DOF you want


Now if the flash runs out of "power" because of high ceilings, you can raise the ISO or open up the f-stop to compensate. Or you can slow down the shutter to bring more ambient light into the exposure (in addition to adjusting ISO/f-stop) If the ceiling is REALLY high (like in a church), you may need a reflector to throw some of the light forward (I use the Joe Demb Flip-it).

Quick and dirty outdoor fill flash tutorial -
Basically, if your subject is in shade and the background is bright (ie under a tree) or majorly backlit, fill flash is your friend. Think of those times when you got a properly exposed background, but the subject was almost pitch black.

Put camera into Av mode, metering will set the shutter speed to expose the overall shot (which in the situations that call for fill-flash will generally be the background) based on your selected aperture/ISO.
Make sure flash is set to HSS (in case your shutter speed go faster than 1/180s) and P-TTL. Fire away! The shutter speed/f-stop/ISO will expose the background, and the flash should output enough power to light up the foreground.

Now to control the background exposure, you use exposure compensation on the camera body (which would adjust the shutter speed), to adjust how much fill for the flash exposure, you use Flash exposure compensation. The trick is balancing the two (as it is with indoor work), and that comes with experience/experimentation.