First of all, forget about fancy flash tricks with the XA-series. They're
designed to accept a specialized type of flash rather than the conventional
shoe mounted units. Consider flash with the XA cameras to be a point and
shoot affair.
Using flash with a leaf shutter camera having user-adjustable shutter speeds
(which includes TLRs and some MF SLRs and every LF camera I can think of) is
fairly simple:
1. First, determine the recommended f/stop based on distance to subject
using the flash unit's guide number or the table printed on the flash.
2. Then take a meter reading to determine which shutter speed is needed to
use that f/stop without under- or overexposing the background.
3. Fire away. For best results, bracket around this basic exposure. If
your flash has adjustable output (like the Vivitar 285), use it to bracket.
If not there are a few tricks: adjust the f/stop; keep the f/stop at the
original setting but place something over the flash to reduce output
(tissue, a diffuser, ND filter, etc); or keep the f/stop at the original
setting and move closer to the subject to increase the flash effect, farther
away to decrease. As little as one foot nearer or farther away can make a
big difference, especially with slow film or slide film.
Opinions differ over what constitutes "fill-flash". Most photographers
regard it as just enough flash to reduce shadows on the face and to add a
catchlight to the eyes. That's fine for circumstances in which reproduction
quality can be controlled. But photojournalists (which I was) generally use
more flash to compensate for the relatively poor reproduction in newspapers.
So I'd usually use a flash ratio approximately equal to ambient light -
sometimes even brighter when ambient light was low.
Here's an example: I've chosen 10 feet as the ideal distance to subject;
with ASA 400 film and my flash I'll set the aperture to f/8; with the
subject in open shade on a relatively bright day I'll need a shutter speed
of 1/500 to prevent blowing out the background at f/8; I take the shot,
knowing that I'll have a photo that obviously looks like flash was used but,
unlike indoor flash, will have a more pleasing appearance because it is
balanced by an equal amount of ambient light.
This particular scenario would be next to impossible with an OM-1 and T20
flash. That combination simply cannot sync above 1/60th. The only
alternatives would be to use slower film, floods or reflectors to supplement
the lighting. None of these techniques would help freeze unwanted movement.
If I want to decrease the flash "look" I could stop down to f/11. But this
would underexpose the background. So I'll compensate by using a shutter
speed of 1/250. Now I have the same EV (exposure value) as before for the
background/ambient lighting, but I've decreased the flash effect by a full
stop.
If, to maintain a preferred depth of field, I want a particular aperture, I
could instead move back and zoom in, or stay put and place something over
the flash to reduce/diffuse its output.
By combining a high shutter speed with flash in daylight or other bright
light you can better freeze action or prevent unwanted movement. OTOH, if
you want to incorporate subject movement or blur along with flash (a popular
trick among fashion photographers and those shooting editorial illustrations
- I use slow sync quite a bit when photographing my exuberant grandsons),
just use a slower-than-sync speed of 1/30 or slower. This can be done with
an SLR or other camera using a focal plane shutter (Leica RFs, etc.) too.
That's the basics. The rest is experimenting to find what works for you.
===========
Lex Jenkins
===========
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