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Photography Question 
Phal 
 

Flash not in Sync


Hi

I have a Nikon N80. When I use the built-in flash with Aperture Priority,
the pictures are underexposed. This though does not happen everytime. I am confused. Should I shoot in 'P' mode when I am using the built-in flash?

thanks


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11/10/2004 10:55:26 AM

 
Jon Close
BetterPhoto Member Since: 5/18/2000
  What aperture are you setting in Av mode, and what ISO film? If you set too small an aperture, your subject may be beyond the useful range of the built-in flash.

The guidenumber for the N80's built-in flash is 39 ft at ISO 100. The maximum useful distance is = squareroot(film ISO/100) x 39/aperture. So, for example, if you're using ISO 200 film and set f/16, the useful flash distance is only about 3-4 feet.

squareroot(200/100) = 1.414.
1.414 x 39/16 = 3.45 ft.


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11/10/2004 1:20:59 PM

 
Phal    Thanks Jon.
I was using ISO 100. I dont remember the Aperture setting. Now I have some more ques
1. Do I always need to do this calc mentally or use a larger aperture to be safe.
2. what diff would it make in 'P' mode.
3. Should I avoid the built-in flash
and use an external instead.

thanks


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11/11/2004 6:42:15 AM

 
Jon Close
BetterPhoto Member Since: 5/18/2000
  You generally should keep the maximum range in mind when using the flash. P mode will probably tend to choose an aperture close to wide open, so with a f/3.5-5.6 zoom the maximum range would be about 7-12 ft. with ISO 100 and 2x that with ISO 400.

If the budget allows, a higher powered accessory speedlight is always preferred over the built-in.


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11/11/2004 7:28:05 AM

 
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