TTL Fill Flash

[alistair o]

Can someone please help me with this scenario:

Using Nikon F5/SB800 combo; bright sunlight; want a little fill

flash; using aperture priority on camera; TTL BL on flash; F4

aperture to limit DOF; camera says the shutter speed is too fast

(i.e. over 250 F5 sync speed).

Question: If i go ahead and shoot anyway, will the camera allow over-

exposure in this situation. If not what does it do:

- overide the aperture setting?

- allow the camera to select a higher shutter speed than 250 (which

i presume will cause a different problem?)

- fail to fire the flash (but i am pretty sure the flash is firing

in this scenario)

 

Geez, I am new to all this automation and I must say manual

everything still looks quite good sometimes!

 

any time taken to help me out on this is would be very much

appreciated.

 

Alistair

[jim_gifford]

I believe the camera will act the same way my N90s would in that situation. If the flash is in the hot shoe, switched on and ready to fire the camera will set the shutter at the maximum flash synch speed of 1/250 second. Your picture will be overexposed.

 

Fix overexposure problem? Close down your aperture until the ambient exposure is 1/250 or less. Select slow flash synch. Alternatively, use a neutral density filter to give you a shutter speed of 1/250 or slower while still using the f/4 aperture for narrow depth of field.

 

And of course you can use manual exposure and flash settings to eliminate entirely any questions of "what will the camera do?"

 

Be well,

[joe_brackman1]

There are two options that I thought of (because I encounter this situation from time to time in my business).

 

One, set the camera to Shutter Priority mode, speed of 1/250 (or does the F5 do 1/300? I use the F100). This way, you're guaranteed to be getting the widest aperture within the sync speed of the flash.

 

Two, use the FP mode of the flash/camera-- that is, high-speed sync. I'm actually not entirely sure the SB-800 does it, but my old SB-28 does. You set the flash to FP mode and the camera preferably to manual mode. Adjust the aperture to get the depth of field you want, and then the shutter speed to get the flash distance you would like (check the flash distance meter on the LCD display of the flash itself). You can use really high shutter speeds; even up to 1/8000, I believe. But the guide number of the flash changes as you change shutter speed, since it's really doing a multi-pop as the shutter travels across the film plane.

 

You'll have to play around to get the shutter speed and aperture that works. Also, you might choose a combo that will underexpose the ambient light quite a bit, even if you get the right flash exposure. Check your camera meter to see what the ambient metering looks like. Up to about a stop under is OK, but beyond that is going to give you a dark background with a lot of flash on your subject. I prefer to have more balance and to minus-compensate any fill flash.

 

BTW, you can minus-compensate in FP mode by choosing an aperture and shutter speed that give a certain distance, and then shoot with your subject at a LONGER distance. For instance, if the flash distance indicator said 10 feet, and you shot with your subject at 20 feet, that would be a one-stop minus compensation (I think my math is correct). You get the idea.

 

So FP mode is really a manual flash mode, and you have to estimate your distance to the subject. It's a game of trial and error, but can give you nice fill flash with a blurred background in high ambient light conditions.

 

The ND filter solution another poster mentioned is a good one, though changing filters can be a little bit of a pain.

 

Oh, also, use relatively slow film. Fuji Reala!