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exposure for flash photos?



 
 
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  #1  
Old August 29th 07, 10:24 PM posted to rec.photo.equipment.35mm
Wm Watt
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Posts: 13
Default exposure for flash photos?

I have a Yashica FX-7 SLR film camera. It is manual except for a built
in exposure indicator. I can adjust the shutter speed and aperature to
get good exposure outdoors but now I'd like to try a flash attachment
and do not know what shutter speed and aprature setting to use. The
built in exposure meter does not work with the flash. I've been
playing around with it with no film in the camera. There is a chart on
the back of the flash attachement but I doubt I can use it for fill in
light indoors by a window? I've looked in photography books at the
public library but they don't say what setting to use. Any advice or
links to advice would be appreciated. Thanks.

  #2  
Old August 29th 07, 10:42 PM posted to rec.photo.equipment.35mm
Draco
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Posts: 706
Default exposure for flash photos?

On Aug 29, 5:24 pm, Wm Watt wrote:
I have a Yashica FX-7 SLR film camera. It is manual except for a built
in exposure indicator. I can adjust the shutter speed and aperature to
get good exposure outdoors but now I'd like to try a flash attachment
and do not know what shutter speed and aprature setting to use. The
built in exposure meter does not work with the flash. I've been
playing around with it with no film in the camera. There is a chart on
the back of the flash attachement but I doubt I can use it for fill in
light indoors by a window? I've looked in photography books at the
public library but they don't say what setting to use. Any advice or
links to advice would be appreciated. Thanks.


Look at the shutter speed dial and see if one of the numbers is in a
differant color or has a lighting bolt next to it. That is the highest
shutter speed the camera will sync at. The flash will fire at any
shutter speed. But will not fire long enough to fill the frame. You
will get a dark area either on one side or the other or at the top or
bottom of the frame. Depending on how your shutter blades travel.
The chart on the back of the flash gives you a distance and
aprature setting for your camera. This is a starting point for your
flash photography. With the aprature set, say f/8, the distance scale
may say between 4 feet to 20 feet, then the camera set at the proper
sync speed most of your images will be lit enough to be reconizable in
this range of distance.

Other than that, try it and see what happens and have fun with long
exposures and flash at either the begining or at the end. See what
happens, but have fun.


Draco


Getting even isn't good enough.


Doing better,,,,does.

  #3  
Old August 30th 07, 01:03 AM posted to rec.photo.equipment.35mm
Jim
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Posts: 323
Default exposure for flash photos?


"Wm Watt" wrote in message
ups.com...
I have a Yashica FX-7 SLR film camera. It is manual except for a built
in exposure indicator. I can adjust the shutter speed and aperature to
get good exposure outdoors but now I'd like to try a flash attachment
and do not know what shutter speed and aprature setting to use. The
built in exposure meter does not work with the flash. I've been
playing around with it with no film in the camera. There is a chart on
the back of the flash attachement but I doubt I can use it for fill in
light indoors by a window? I've looked in photography books at the
public library but they don't say what setting to use. Any advice or
links to advice would be appreciated. Thanks.

As another poster mentioned, there is likely to be an indication on the
shutter speed dial of the correct setting.
If you take the back of the camera off, you can observe the action of the
shutter. I suspect that this camera has
two horizontal curtains; if yours doesn't, then ignore what I am posting.

A focal plane shutter moves the shutter curtains independently at low
speeds. One of them opens the film gate to
light, and the other closes it. At these speeds, the film gate is always
completely open to the light. However,
since the shutter curtains traverse the film gate in a fixed time, there is
a shutter speed where the first curtain opens the
gate while the second immediately closes it. This is the maximum shutter
speed for use with a flash. At shorter
durations, the curtains move in concert with a variable width slit for the
light to get to the sensor.

As for exposure, you must use the guide number method. In this method, you
divide the guide number for the
flash and for the film by the distance to the subject. The result is the
fstop. This is the method that was used for
many years (before the development of automatic flash exposure control).

That is to say, every flash has a certain amount of light which it outputs.
Every film is sensitive to a certain amount of light.
Hence, one can construct a guide number for a given film type and for a
given flash.

Jim


  #4  
Old August 30th 07, 02:56 AM posted to rec.photo.equipment.35mm
Ric Trexell
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Posts: 114
Default exposure for flash photos?


"Wm Watt" wrote in message
ups.com...
I have a Yashica FX-7 SLR film camera. It is manual except for a built
in exposure indicator. I can adjust the shutter speed and aperature to
get good exposure outdoors but now I'd like to try a flash attachment
and do not know what shutter speed and aprature setting to use. The
built in exposure meter does not work with the flash. I've been
playing around with it with no film in the camera. There is a chart on
the back of the flash attachement but I doubt I can use it for fill in
light indoors by a window? I've looked in photography books at the
public library but they don't say what setting to use. Any advice or
links to advice would be appreciated. Thanks.

************************************************** **************************
*********
Wm Watt: I think you got good advice but I think Jim misunderstood what you
were saying. (Maybe I misunderstand.) Anyway, you asked about using it
indoors with fill in light from a window. I doubt there will be that much
light coming from the window that will be stronger than your flash. I would
just shoot with the flash and not worry about the light from the window.
Now, if you are outside, what Jim said is right. That may be a little
advanced for someone that doesn't have a clue as to the what shutter speed
of the camera is for flash, so that is why I felt Jim was misunderstanding
your question. If you wanted to use fill flash for outdoors, then figure
that your flash probably has a guide number of about 80. The big potato
smashers go about 100 or more. Most of the ones made that attach to the
camera though are in the 80 range. So if you are using 100 ISO film, and
your subject was 10 ft. away, the f/stop to use would be f/8. That is 10
divided into 80 = 8. If you are using 200 speed film, then go to f/11. It
is always easier to figure it with 100 speed film and then add or subtract
f/stops I think. If you have an automatic flash that has a little electric
eye, then don't worry about it. The flash will make that decision. Ric in
Wisconsin.


  #5  
Old August 30th 07, 04:05 PM posted to rec.photo.equipment.35mm
Wm Watt
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Posts: 13
Default exposure for flash photos?

Thank you for the helpful information. The camera has an indicator at
shutter speed 1/125. I was able to find instructions on the Internet
for the camera and it is synchronized for flash at that shutter speed
but I did not know what that meant. Now I do. The flash is called an
Image CZ-55 for which I have not found instructions on the Internet.
The flash has a switch for M (manual) and three automatic settings,
but the camera does not have automatic exposure, just manual. I
appreciate the exposure computations very much.

At present I am interested in taking some portrait type photos using a
collection of hats indoors with natural window light, using the flash
to bounce light off a wall to reduce shadows. I have neither studio
and nor experience so am improvising.



  #6  
Old August 30th 07, 05:08 PM posted to rec.photo.equipment.35mm
Jim
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Posts: 323
Default exposure for flash photos?


"Wm Watt" wrote in message
ups.com...
Thank you for the helpful information. The camera has an indicator at
shutter speed 1/125. I was able to find instructions on the Internet
for the camera and it is synchronized for flash at that shutter speed
but I did not know what that meant. Now I do. The flash is called an
Image CZ-55 for which I have not found instructions on the Internet.
The flash has a switch for M (manual) and three automatic settings,
but the camera does not have automatic exposure, just manual. I
appreciate the exposure computations very much.

At present I am interested in taking some portrait type photos using a
collection of hats indoors with natural window light, using the flash
to bounce light off a wall to reduce shadows. I have neither studio
and nor experience so am improvising.



The three automatic exposure settings allow the flash to determine when
enough is enough. You will find them much easier to control than the purely
mechanical method.

In most instances, you set the flash to a particular automatic mark.
Associated with the flash setting and the film speed is an fstop. You set
the camera to this fstop.
Then you just shoot away.

Jim
Jim


  #7  
Old August 30th 07, 11:37 PM posted to rec.photo.equipment.35mm
Ken Hart
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Posts: 154
Default exposure for flash photos?


"Wm Watt" wrote in message
ups.com...
Thank you for the helpful information. The camera has an indicator at
shutter speed 1/125. I was able to find instructions on the Internet
for the camera and it is synchronized for flash at that shutter speed
but I did not know what that meant. Now I do. The flash is called an
Image CZ-55 for which I have not found instructions on the Internet.
The flash has a switch for M (manual) and three automatic settings,
but the camera does not have automatic exposure, just manual. I
appreciate the exposure computations very much.

At present I am interested in taking some portrait type photos using a
collection of hats indoors with natural window light, using the flash
to bounce light off a wall to reduce shadows. I have neither studio
and nor experience so am improvising.


The manual setting puts out a fixed amount of light. The intensity of the
light hitting the subject depends on the distance from the flash to the
subject, and brings up the whole "guide number" calculation thing. (The
intensity of the light decreases with the square of the distance, divided by
the phase of the moon, and multiplied by the gross national product of
Luxomburg!)

The automatic settings measure the amount of light that hits the subject.
For each auto setting and film speed, there is an associated f/-stop. Set
the camera to that f/-stop and in most situations, the exposure will be
correct.

For your fill-in flash application, determine the exposure for the light
coming thru the window. Let's assume that it is f/8 at 1/125 sec (You are
limited to using your synchro-speed of 1/125 sec). Hopefully, one of the
flash's auto settings for the film you are using will be f/5.6. Expose for
the window light (f/8) and set the flash for one-stop down (f/5.6). The
window side of the subject will be properly exposed, and the other side will
be lit, but slightly less, probably a better look than having both sides
equally lit.

(Caveat: how does your camera meter the scene? If it looks at the _whole_
viewfinder, and the area around your subject is dark, it will select a
setting that averages the light and dark areas together. Move closer so that
the well-lit subject fills the whole frame, get your exposure setting, then
move back to where you want to be. If your camera meters on a certain area
in the center of the viewfinder, then just make sure your subject fills that
area.)


  #8  
Old August 31st 07, 12:54 AM posted to rec.photo.equipment.35mm
Ric Trexell
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Posts: 114
Default exposure for flash photos?


"Wm Watt" wrote in message
ups.com...
I have a Yashica FX-7 SLR film camera. It is manual except for a built
in exposure indicator. I can adjust the shutter speed and aperature to
get good exposure outdoors but now I'd like to try a flash attachment
and do not know what shutter speed and aprature setting to use. The
built in exposure meter does not work with the flash. I've been
playing around with it with no film in the camera. There is a chart on
the back of the flash attachement but I doubt I can use it for fill in
light indoors by a window? I've looked in photography books at the
public library but they don't say what setting to use. Any advice or
links to advice would be appreciated. Thanks.

************************************************** **********************
Dear Wm: Another thing you might try is to go down to your local paper or
office supply store, and purchase a white foam board. (I got mine at
wal-mart). If the light is strong enough for the reflector, it will lighten
up the shadows. If you want, try some aluminum foil or a sheet of aluminum
to reflect light back. If it is too much, crinkle it up (the foil not the
sheet) and try it that way. Have fun. Ric in Wisconsin.


  #9  
Old August 31st 07, 03:19 PM posted to rec.photo.equipment.35mm
hickster11
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Posts: 96
Default exposure for flash photos?


"Wm Watt" wrote in message
ups.com...

At present I am interested in taking some portrait type photos using a
collection of hats indoors with natural window light, using the flash
to bounce light off a wall to reduce shadows. I have neither studio
and nor experience so am improvising.


The 1/125 sync speed means 1/125 or slower. So if you meter

for window lite and want to use say f4, and the meter says f4@1/60 ,that's
fine. Then move the "Auto" slider or knob on the flash till it says about
f4. You will still have to make tests, and I"ve found many flashes to be a
little optimistic. If you can bounce it off a card taped to the flash, it
should diffuse it enough. Bob Hickey


  #10  
Old September 1st 07, 02:21 PM posted to rec.photo.equipment.35mm
Alan Browne
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Posts: 12,640
Default exposure for flash photos?

Wm Watt wrote:
I have a Yashica FX-7 SLR film camera. It is manual except for a built
in exposure indicator. I can adjust the shutter speed and aperature to
get good exposure outdoors but now I'd like to try a flash attachment
and do not know what shutter speed and aprature setting to use. The
built in exposure meter does not work with the flash. I've been
playing around with it with no film in the camera. There is a chart on
the back of the flash attachement but I doubt I can use it for fill in
light indoors by a window?



The key thing to remember is you're really making two exposures: 1 with
natural light (shutter speed and aperture) and one with flash light
(aperture only).

Fill light is typically 1 to 2 stops (or more if you like) less than the
key light.

For fill light set your exposure according to the key light (natural)
and set the flash to 1 / 1.5 / 2 stops "more open" (corresponding to a
faster aperture than the actual lens aperture). The flash will "under
shoot" as it believes the aperture is more open than it really is

For example. If the key light (natural) indicates a 1/125 f/8 shot,
then set the flash for f/5.6 (1 stop open) to get a moderately strong
fill; or f/4 to get a shadow lifting fill.

-or-

If you can't control the flash power this way, then set the lens
aperture according to the flash guide, then close the lens aperture down
(1/2, 1, 2 stops) and open up the exposure time in reciprocal amounts to
balance the natural light.

For example: the meter reading is again 1/125 f/8 for the natural light.
The flash setting is for f/8 at the distance you're shooting. Set the
lens aperture for f/11 (1 stop down for fill) and open up the shutter
speed to 1/60.


Cheers,
Alan.

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