Fill Flash Question.

[FreeloaderJoe]

I was under the impression that the aperture controlled your subjects lighting and the shutterspeed essentially changed your shutter speed. Some messing around tonight and i haven't quite managed to achieve those results.

Is that how photos like this are achieved: http://www.flickr.com/photos/ockermedia/3044456416/ short high power flash burst with a largish aperture and a long shutter?

 

[Lensflare]

Long shutter on a tripod. Then punch in a BIT of flash to suit the lighting you want on the foreground subject.

I would say that shot you linked to had -ve FLASH exposure comp in it. In other words the aperture and shutter were balanced for the ambient, maybe down a bit (I can't remember now and I can't go back because I have started typing! If you can, that is beyond my techy knowledge of driving a confuser) and the flash has just been added to lift the foreground a bit but not fully expose it.

You will need to experiment a bit with a mug prepared to stand there while you do some comparitive shots. the trails are easy, it is the light on the foreground subject that requires the balancing to get a natural effect. All too easy to overpower the foreground with flash and make it look too obvious you have lit it.

having gone back and had another look - stand the subject UNDER a street lamp - look at the shadow, it is a pool shadow showing lighting right above.

 

[Jayst84]

Flash exposure if controlled by the output of your flash, your ISO and your aperture.

Ambient exposure is controlled by ISO, aperture and shutterspeed.

So, changing your shutterspeed will effect the ambient, but not flash exposure.

If there is flash used in a situation like the one you linked to:

Settings would probably be, low ISO, long shutterspeed and small aperture with fairly high powered flash. You would need a strong flash due to the small aperture, then the ambient is balanced by use of the long shutter.

 

[HoppyUK]

I was under the impression that the aperture controlled your subjects lighting and the shutterspeed essentially changed your shutter speed. Some messing around tonight and i haven't quite managed to achieve those results.

Is that how photos like this are achieved: http://www.flickr.com/photos/ockermedia/3044456416/ short high power flash burst with a largish aperture and a long shutter?

I don't think any flash has been used in the linked pic. Just a long exposure of maybe three or four seconds judging by the length of the bus light trails and the lady standing very still. Tripod, white balance set to tungsten or preferably custom white balance (street lighting is often an unpredictable colour).

You're right about flash though. Shutter speed has no effect on the flash exposure, that is controlled by the f/number and then the shutter speed is adjusted to balance the background exposure. It's not difficult. You could probably do something like the linked pic, if you wanted to use flash, just by shooting on aperture priority and TTL auto flash. You'd get a result that way for sure, then tweak it with +/- compensation to suit.