
I thought I would share a fun technique that I used while shooting a a recent wedding reception. This image was created with an on-camera flash with the Black Foamie Thing bounced into the ceiling and a slow enough shutter speed to allow the ambient light to register while rotating the camera.
I arrived with these results using the knowledge that a subject that is lit predominantly by flash will be sharp and "frozen" in an image with a slow shutter speed. The exposure for this image was manual f2.8, 1/3 sec. @ ISO 640 and flash set to TTL. I was already shooting at f2.8 and ISO 640 simply because I was indoors and bouncing flash so I needed settings that would be "easy" for my flash to out put enough light to give me proper exposure and not work my flash too hard since I was shooting quickly.
Flash exposure is not influenced by shutter speeds less than the camera's sync speed so when I am deriving my initial settings for a flash dominant scene I am concerned with aperture and ISO. The larger the aperture and the higher the ISO the less light the flash has to put out. Once I have those settings to my liking, I will adjust the shutter speed to obtain my results as far as ambient is concerned. The slower the shutter speed the more the ambient light will contribute to the image. Of course aperture and ISO influence ambient exposure as well, but indoors when I am using flash as the main light source I am not overly concerned with those settings unless they don't allow me to control the ambient with shutter speed alone.
With my aperture and ISO set I simply slowed the shutter speed down until it was slow enough to allow me to rotate the camera during the exposure in order to make the room and DJ's lights streak in the image. I just snapped away and adjusted my shutter speed until I had the desired effect. It so happened that 1/3rd of a second shutter speed allowed this to happen. Let's say I couldn't get a slow enough shutter speed to allow enough time to rotate the camera without over exposing the ambient I could have lowered the ISO or increased my aperture since those settings not only influence the flash exposure they influence the ambient exposure as well.
So let's say that I needed at least 1/3 of a second in order to rotate the camera, but the image was over exposed. If I changed my aperture to f4 or my ISO down to ISO 320 I would have reduced the ambient exposure by one stop, but still giving me the time to rotate the camera before the shutter closes and the beauty of using my flash in TTL is that the flash will automatically compensate for the change in aperture or ISO by putting out one stop more light.
I hope this all makes sense. Combining flash with ambient especially with a slow shutter speed can produce some fun results. This same technique can be used and instead of rotating the camera you can zoom your lens in or out to produce interesting results or just move the camera sideways - experiment. Since the subject is exposed by the flash they will remain decently sharp - depending on how slow your shutter speed is. Remember, the slower it is the more the ambient will record on your moving subject and that motion will begin to record on the sensor for an interesting effect should you choose to let that happen.













































































Had a great shoot and a fun evening, hope it's now easier for us to get together, as summer is nearly over :-( I guess we all just got too busy for our own damn good. 



