basic fill in flash

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wally - 03 Jul 2005 03:18 GMT

my camera has a flash syncronization of 1/50th secound. even with a 100
speed film the light meter calls for f4 with 1/250th secound.
How can the camera be set for fill-in flash with a manual flash.
any help would be appreciated.

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dadiOH - 03 Jul 2005 14:57 GMT

> my camera has a flash syncronization of 1/50th secound. even with a
> 100 speed film the light meter calls for f4 with 1/250th secound.
> How can the camera be set for fill-in flash with a manual flash.
> any help would be appreciated.

Uhhh...by adjusting the f-stop to the necessary shutter speed; eg...
1/250 @ f4 to 1/50 @ f8
then dropping one stop (or more) smaller to (1/50 @ f11) so that the
flash fills rather than dominates.

--
dadiOH
____________________________

dadiOH's dandies v3.06...
...a help file of info about MP3s, recording from
LP/cassette and tips & tricks on this and that.
Get it at http://mysite.verizon.net/xico

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dadiOH - 03 Jul 2005 17:12 GMT

>> my camera has a flash syncronization of 1/50th secound. even with a
>> 100 speed film the light meter calls for f4 with 1/250th secound.
>> How can the camera be set for fill-in flash with a manual flash.
>> any help would be appreciated.

Scratch the following quote, hadn't had my coffee...

> then dropping one stop (or more) smaller to (1/50 @ f11) so that the
> flash fills rather than dominates.

_________________________

Now, let me try again. For fill in flash, try to think of making two
photos...one with the correct exposure for the ambient light, the other
with flash with an exposure less than would be required. How *much*
less depends on what effect you want. If you want open shadows, one
stop less is about right.

OK, you have to use 1/50 max for your camera to sync, right? And your
meter says that 1/250 @ f4 is the correct exposure for ambient light.
It will also tell you that 1/50 @ f11 is the same exposure. Since that
is your sync speed, you have to use that (or another slower shutter
setting like 1/25 @ f16) in order to properly expose for existing light.

Next you have to determine the flash exposure. You need to know the
guide number of the flash for a given film speed and the distance you
will be from the subject. Dividing the guide number by the distance
will give you the correct f-stop for *just* the flash. Suppose for
simplicity sake that the calculation tells you that you should use f8;
since you want to fill in and have open shadows, you want to underexpose
the flash by one stop which means you should use f11 which means that
1/50 @ f11 is correct for *both* ambient and flash light in this case.

But what if the guide number/distance result isn't as convenient in the
above example? If you need a smaller aperture you can either use it or
decrease the amount of flash. Many flashes let you choose 1/2 power,
1/4 power, etc.; if not, you can decrease the flash power by putting a
white handkerchief over it...each layer decreases output about one stop.

If you need a larger aperture for the flash you would have to move the
flash closer to the subject since you couldn't adjust the ambient light
shutter/f-stop combo without loosing sync...that is the problem with
focal plane shutters. Practically, you would just shoot anyway knowing
the flash exposure is less than you want.

--
dadiOH
____________________________

dadiOH's dandies v3.06...
...a help file of info about MP3s, recording from
LP/cassette and tips & tricks on this and that.
Get it at http://mysite.verizon.net/xico

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