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Old Oct 22, 2005, 4:03 PM   #1
AMG
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Hi, I don't actually want a critique, but rather some help. I have the same pic taken twice. I thought I understood quite well what a camera does behind the scenes. One pic has the fill flash used and the other doesnt, but the one with fill flash has underexposed the background. I used the regular matrix metering in aperture priority mode with HSS turned on in my flash. The other pic has same settings only no flash. I expected the one with fill flash to have the background the same as the pic with no flash, but with the subjects looking like they do in the fill flash pic. I do not want to go manual if possible, I like the creative zone modes. Anway, camera is canon elan 7e and speedlight 420 EX. I am thinking of getting rebel XT but pics would have come out the same I'm sure. thanks a lot.
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Old Oct 22, 2005, 4:03 PM   #2
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and second
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Old Oct 22, 2005, 5:04 PM   #3
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Do not use HSS mode on the flash and it should fix the problem.
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Old Oct 22, 2005, 7:07 PM   #4
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also dial in a negative FEC on your fill flash.. maybe between -1 and -1.5ish..

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Old Oct 22, 2005, 7:32 PM   #5
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widowmaker, could you explain please, my understanding is HSS will only make a difference if the shutterspeed is faster that 1/125 other wise no change, and in this case I believe shutter speed that was chosen by camera after I picked the aperture was 90 oe 125 so what difference could it possibly make,

And Hards80, thx for the tip, but why should I have to do that, isnt the flash supposed to balance the foreground and background. It is as if something is not performing as promised.
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Old Oct 23, 2005, 10:04 AM   #6
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My bad for assuming you had reason for shooting in HSS mode. Your right, if the shutter speed is below you cameras sync speed HSS is not going to change the shot but it is also not necessary to have it enabled.

What you are experiencing is a phenomenon called NEVEC (Negative Evaluative Exposure Compensation). It has to do with the 420 flash and some camera bodies (not all).

The way to see if this is your problem do the following.

Set the camera on a tripod inside with the flash mounted and on.
Make sure you are in evaluative metering and AV mode.
Meter an area that will give you a shutter speed below your cameras sync speed (something below 125).
Be sure the lighting is not changing on you by watchign the shutter speed. It should remain at one setting and not change.
Once that is done turn the flash off while the shutter speed is still visible.
If the shutter speed changes when you turn the flash off you are experiencing NEVEC.

The way around this is to set the camera to center weighted metering instead of evaluative. Do the same steps as above but use center weighted metering and the shutter speed should remain the same with the flash on and off.


Do not try to do this handheld because any slight movement on your part will result in changes to what the cameras is seeing and the shutter speed will change accordingly.

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Old Oct 23, 2005, 1:44 PM   #7
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thx widow, but now thinking of the lighting conditions again and looking at all my results, I think I have learned something but am wondering how to overcome my problem. whatever the manual says, im am sure what happens is the following, flash off, the exposure is perfect, but my subject has those ugly shadows and you can't see their true eye color, and no catchlight in the pupil, flash on, the camera may indeed tell the flash to burst minimally but because the subject is well exposed to begin with, the shutter speed is increased so that the subject won't get overexposed, and therefore the background is underexposed because the camera assumes you want to expose the subject properly. summary, you cannot use fill flash succesfully if you're subject and background are similarly bright, you really need a brighter backgrounbd for the math to work. so what can one do ? I really want to use my flash outdoors.
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Old Oct 23, 2005, 2:07 PM   #8
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Sounds like NEVEC. I thought it was flash related it is actually camera related. I will try and find the article on it.

Try center weighted metering and see what happens.
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