Built in flash sync

shogran

shogran

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Name
Josh
Edit My Images
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Hi there,

Another basic question that I hope someone can hope me with. If I'm in a situation where to get any kind of decent photo I need to use my cameras in built flash (EOS 450D), does the flash sync itself to the exposure time I choose (in manual mode) to provide the correct flash or will I have to work out what to set my exposure time to?

For example if I pop the flash up, and set the exposure to 1/100 will the image be correctly exposed or does it depend on the enviroment I'm in and the subject?

Thanks in advance and apologies for another silly question!

Josh
 
I believe you will find the camera will work it out for you. If in low light and in M mode you may need in some cases a tri pod so the camera can use the ambient without blurring. In Auto mode e.g the camera will set an exposure at a faster sync and will just use a stronger flash and not capture any ambient. If you are shooting landscapes in the dark though, don't use flash as they will be useless............a long exposure on a tripod will then be required.
 
With the pop-up flash, it's very hard to get the flash exposure seriously wrong - the camera won't let you. It will always attempt to match the flash output to the lens aperture, however that is set. The flash is unaffected by shutter speed, so long as you stay below the max x-sync speed, which is 1/200sec on a 450D, but with the pop-up it won't let the camera go above this speed anyway whenever the flash is charged and ready to fire.

The different modes will handle the ambient light exposure differently, ie the background, which is largely unaffected by the flash.

What is it that you are trying to shoot and what effect are you after?

Edit: if you want the background correctly exposed and the flash as well, then use Av - this will track it automatically and the flash exposure will balance it. But if it is dim or dark, the shutter speed will obviously get very long (up to 30 seconds) so you have to make a few decisions.

Double edit: in the video link below, that's what he's doing. He's using manual to 'drag the shutter' or you can use Av which does the same thing automatically.
 
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Look at this Mungo-Jerry-lookalike vid. It's not the best, but explains a little more clearly what I'm trying to explain (I hope;-) )Although not iin the case so much as this guy's example, in many cases, in auto the bg can come out extremely dark, but choosing a slower shutter speed in Manual , you will have a lighter bg as you capture the ambient light too. http://www.youtube.com/watch?v=LzliksKaNyM
 
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