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04-27-2010, 11:48 PM   #1

K-x flash in AV mode


I'm a little bit confused about flash. I use mainly two modes: manual discharge and slow sync. I was expecting shutter speed 1/180 in manual discharge mode, but no, camera measures this value and sets what it like. So the question is why do we need slow sync mode if I get the same F and shutter speed values ? What is the difference between two modes if camera measures the same exposition parameters ?

04-30-2010, 02:36 AM - 1 Like   #2
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flash confusion

You are confused indeed! You think manual discharge mode in Av is the same as Manual mode on the circular dial on top of the camera.

Obviously it isn't.

When you select the Manual mode, you can set any speed you choose up to 1/180s and any aperture you like, at any ISO you prefer.

In Av mode, you have selected manual discharge on the flash settings - what this means is simply that you have to manually pop the flash up in order to use flash. It does not affect the flash speed. When the flash is up, the camera will select a speed to match the aperture you have selected to ensure a photograph that exposes for ambient light, not for the flash that you are adding. The flash will in fact adjust itself to try to balance against the ambient light setting selected by the camera. In worst case scenarios, one can't really see that the flash made much of a difference.

In slow synch, you are asking the camera to select a longer shutter speed - not for the flash itself but to ensure that the background light in a dark scene e.g. evening shots is captured as well as the foreground scene, which will be illuminated by the flash. The manual makes a reasonable attempt to explain the difference so please look at it again.

In some cases, e.g. relatively dark conditions, the shutter speed for both settings will be the same since the camera is trying to expose for ambient light and will naturally have to use a slow shutter speed.

Here's a great tip I got from another user - set your camera to Manual mode (top dial). Pop up the flash, focus and press the green button - the manual settings will adjust themselves to the conditions (for whatever ISO you selected), both the speed and aperture may change - take the shot - you will get a great flash exposure.

Try taking a picture in daylight using Av but with the subject in shadow.You should see a difference then in the shutter speed selected by the camera between 'manual flash discharge' (the first flash setting) and 'slow synch' flash.
04-30-2010, 03:13 AM   #3


That was awesome and informative answer. Now everything is clear to me. Thank you !

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