need help with fill flash

[camerageak]

when shooting in bright sun i have the people put there backs to the sun of course causing shadows on there faces.i shoot in manuel and i get a correct setting but when i turn on the flash it goes to a speed of 250 which causes over exsposure .how can i get the shutter speed i need? thanks for any help. p.s. i do cut the flash power but no help

[Ozzie_Traveller]

G'day CG

You have not given us the type of camera - and therefore the shutter type- that you are using
I will presume that you are using a dSLR, therefore it has a focal-plane shutter

For flash + focal plane shutter work, the flash must fire when the 2 curtains of the shutter are fully open ... and that is usually at shutter speeds of 1/125sec and slower. If you try to take flash photos at speeds faster than 1/125, you will only get half-a-photo from the flash because the shutter blinds will only be half-open

For your camera to have a flash-sync of 1/250sec, it tells me that it's a pretty new dSLR

So now you come to the age-old dilemma of sync-flash > ie- the balancing of flash-light to day-light
Presuming that the daylight exposure is ... 1/250 x f8 x ISO-100 [just for this discussion]

1- For your flash power to equal daylight, your flash exposure must also equal f8 x whatever flash-to-subject distance is involved ... and that usually means a big, powerful flashgun

2- For your flash power to be 1/4 daylight and thus be used to fill in the shadows [rather than equal the sunlight] your flash-to-subject distance can be doubled from 1- above, which makes it a bit easier for you too

This is where the Canon/Nikon/other expensive flashguns [often called speedlites] come into things ... with the multiple contacts in the top of the camera to connect with the flash and work out all the settings for you

For simple non-computerised flash guns, it's personal experimentation on your part to set it all up via lots of testing in your back yard

There are lots of books around on flash work - the 'bible' is often quoted as being "The Speedliter's Handbook" by Syl Arena, ISBN-13 978-0-321-71105-2 and costing $40-$50

Hope this helps a bit
Regards, Phil

[camerageak]

i have a canon 50d with 580ex flash.as an example if the correct shutter speed is 1/500 with an fstop of 5.6 then when i turn on the flash with reduced power the camera will give me shutter speed of 1/250 and the picture is over exsposed .hope what i am asking makes since.thanks

[Bob Nichol]

As Phil pointed out, shutter speeds faster than 1/250 with your 50D's focal plane shutter will result in a black bar along one edge of the image because the second curtain has begun to close when the flash is fired so the camera overrides the shutter speed to 1/250. This is a physical limitation of focal plane shutters.

You can stop down the lens to f/8 or use neutral density (ND) filters to compensate.

[VTphotog]

1/250s is the fastest your camera can shoot with flash. Not sure if you have a high speed sync option which would allow you to use faster speeds, but if not your option is to switch your camera to aperture priority and use a smaller aperture, such as f/8 or f/11, so your shutter speed will be slower than the flash sync speed. This should allow the flash to compensate with some fill.

brian

[BillDrew]

You might be able to use slave flashes that are closer to the subject, or enough of them to give the light you want.