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Photography Question 
Barbara Helgason
BetterPhoto Member Since: 1/4/2004

Fill Flash Frustration...

I've read, searched, but it's just not working. Every time I try to use fill flash outside - on a portrait to lift the shadows - I end up with a totally overexposed picture. I'm using aperture mode on my Rebel XT, as suggested on the Canon Web site, an on-camera flash, with the flash at -2 ... and still overexposure. What am I missing here?

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10/7/2006 5:37:55 PM

Mike Rubin
BetterPhoto Member Since: 10/15/2004
  There are a lot of things to consider, such as Distance & Ambient light. Also are you recomposing after focusing? If you are then you need to also use FEL.
Here are a few great links on Canon Flash, Which operates as no other brand does. I hope they help.

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10/7/2006 8:16:25 PM

W.    Have you looked at the EXIF data of those overexposed shots, Barbara? Are they slow? Like slower than 1/125th sec (flash sync speed on many cams)? Then your cam is metering ambient light and exposing for it. If that is the case, your cam is, obviously, not in flash mode. So when you add flash into the mix it overexposes.

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10/8/2006 5:07:17 AM

Barbara Helgason
BetterPhoto Member Since: 1/4/2004
  Thanks for your answers guys, Mike those are some great sites, looks like I have some reading and practicing to do. Thanks.

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10/8/2006 6:26:59 AM

Jon Close
BetterPhoto Member Since: 5/18/2000
  What aperture and ISO are you trying to use? In Av mode with a flash, the fastest shutter the camera can set is 1/200 (unless using a speedlight set for FP High Speed Sync). If you set too wide an aperture, then the camera cannot set a fast enough shutter speed to prevent overexposing the ambient light. The XT warns of such overexposure by blinking the shutter speed in the viewfinder.

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10/9/2006 7:17:53 AM

Gerald Kurata   As you discovered, the Canon flash default settings are too strong on some bodies. With the 20D I sometimes had to use a FEC of -3. On the 5D I use -1/2 or -1 with a 580 EX. BTW, with the 580 I always use a diffuser.

Just the way they work.


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10/9/2006 2:36:34 PM

Barbara Helgason
BetterPhoto Member Since: 1/4/2004
  Thanks guys, I've been reading the above sites and I think I finally got it when I read this line:
"It's overexposed from ambient light because the shutterspeed was too slow. If you're using fill flash in bright situations, it's necessary to stop down the aperture to get the shutter speed below flash sync." Jon exactly what you were saying, thanks again. I finally understand now.

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10/9/2006 3:30:53 PM

anonymous A.    I have had excellent result in this situation by simply leaving the Canon in "P" mode with flash compensation of -1.

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10/10/2006 6:38:26 AM

Denny L. Pearson
BetterPhoto Member Since: 9/28/2006
  What brand of flash are you using? I tried using a non Canon brand on my old Powershot Pro 1 and could not control the intensity of the flash output. If the unit is not compatable with your camera it will fire at full power if it fires at all. Bought a Canon Speedlight and it makes beautiful exposure under every condition I've used it in.

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10/10/2006 3:33:07 PM

Ben LindoPhotography   Thats funny, I recently tried out canon Mark 1ds Mark II or whatever the top of the line canon camera is called and tried shooting outdoors with a fill flash and Had the same thing happen. I was using the 70-200 2.8L IS lens. Probably around 2.8 because I like the background blur effect.

I had the same problem and was blaming the 'stupid camera' lol. Even turning the flash exposure compensation as low as it would go didn't help.

Later I did the same thing with my Nikon D70s camera and realized it wasn't the camera the flash that was doing something wrong, it was me, silly me.

Using such low aperature's in daylight means the camera must use a fast shutter speed for proper exposure, but using flash limits your shutter speed to the flash sync speed, usually 1/200 or 1/250 maybe 1/350 or something, ON my nikon Its higher than most cameras its 1/500 but still It may not be high enough for fill flash sometimes, especially with a 1.8 lens! :)

Sorry, this is a long rant. I hope it makes sense to you.

For the fill flash to work properly you should put the ISO to lowest possible and you may have to stop down to f/8 or something.

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10/10/2006 5:38:00 PM

Robert  Weeks   One problem that complicates this issue is "what area of the photo shot is being used to detect the reflected light." If you are spot mode and most of the frame is brightly lighted your camera has opened the F stop to expose shadows properly and the flash sensor may not be as accurate due to the large EV of the overall ambient light resulting in an overexposed image.

You may have to make adjustments as mentioned in above responses due to what ever your actual setting was between strobe and camera.


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10/13/2006 4:56:00 PM

anonymous A.    Just tgo add to Ben's thought... Wit the pop-up flash and non-Canon gund, the sync speed for my 20D is 30 secs to 1/250. With Canon's EX series flash guns, the 1/250 upper limit no longer applies. You may find that your model also performs at a higher max with an EX gun.
I don't have the Canon flash, by the way...I use a Nissan, so my good results in P mode have nothing to do with the high spec flash.
Incidentially, I think the typical main to fill ratio is 1:3, and the Canon supplies that ratio automatically in Auto and P modes. Under normal circumstances, Barbara, I think you should see how it performs in P and use that as your stating point if you want to work in Av.

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10/14/2006 12:03:43 AM

Ben LindoPhotography   David R, to my understanding the 1/250 limit still applies no matter what type of flash your using. Theres something called a highspeed flash feature with some cameras and flashes, but apparently it doesn't really work (or it doesn't always work or its a marketing trick or something, im not sure).

But I use an Nikon Sb800 flash and it wont let me go above my cameras flash sync speed which is 1/500, with the external flash or onboard flash the sync speed is the limit.

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10/14/2006 6:39:13 PM

anonymous A.    Not so, Ben...with Studio Flash/strobe, the sync speed is limited to 1/125 from memory; with the pop-up, 3rd. party and older Canon units its 1/250, but with EX series, the upper limit is removed because the flash strobes to compensate for the focal plane shutters movement across the sensor.

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10/14/2006 7:53:45 PM

anonymous A.    I just checked ...the sync speed with a 380EX is 1/2000

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10/14/2006 8:04:45 PM

Rom A.G.   set exposure compensation to -1, but flash's EC set to 0.0;
place subject further away and use zoom;
use shutter speed above 1/500th;

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10/15/2006 7:24:08 PM

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