David Farber wrote:
I was wondering about how fill flash affects the existing light. Of course
it will take the shadows and lighten them up a bit, but what about the parts
of the picture that are correctly exposed by the existing light? I mean the
light emanating from the flash (attached to the hot shoe) does not just go
to the shadows. Wouldn't the areas not in shadow then be overexposed by a
half stop? My fill flash photographs (from print film) have been coming out
nicely but this conundrum has me scratching my head. On second thought,
should I be using some ratio method to compensate for the existing light
exposure or is that not how it's done? I'm using a Minolta Maxxum 7 with a
3600HS flash unit.

For the sake of fill flash, don't worry about it. Yes, they are additive.

The Maxxum 7 has TTL-OTF metering for the flash. That is to say, light
coming off of the subject bounces off of the film into some sensors at
the bottom of the mirror box. When the flash return is adequate the
flash is stopped.

Assuming you are shooting in A-mode or P mode, the camera will determine
the shutter speed (and the aperture for P mode too) based on the
available light and the fact that the flash is on.

If the subject is that famous neutral grey of 12%, then simply set the
flash compensation wheel to -1, -1.5, -2 depending on how much fill you
need. For a lighter subject offset that setting to the positive; darker
offset further negative. (This applies for both the flash and the
available light compensations).

When you depress the shutter, the camera will set the shutter speed
(assuming A-mode) for the ambient light. Since you set a compensation
for the flash (above) that will quench the flash when that level of
flash return is received. For the balance of the exposure period, it
will be ambient based on the shutter speed. (Same for P-mode, but the
aperture is also chosen; opposite for Speed (and mind sync and other
limitations).

See the manual as well (I have a Maxxum 9 and Maxxum 7D; not the 7).
They explain this in some detail.

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