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Old Oct 8, 2007, 12:23 PM   #1
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I have a Minolta 7D with a 5600 flash and I have just got two Studio Strobe Flash units - 1. If I wish to have the stobes fire as a slave from the 5600 flash what settings do I use? I tried this in P mode andit did not seem to make any difference having the stobes with the 5600 flash. 2. If I connect the stobes via a pc cord to the camera and do not use my 5600 flash what settings do I use? I tried this but without the 5600 attached, the camera used a very slow shutter speed in P mode - which will requre the use of a tripod ( which I do not want ). I have purchased the Studio Stobes for use in wedding photography to help light up the church.
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Old Oct 8, 2007, 1:04 PM   #2
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georgegandalf wrote:
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I have a Minolta 7D with a 5600 flash and I have just got two Studio Strobe Flash units - 1. If I wish to have the stobes fire as a slave from the 5600 flash what settings do I use? I tried this in P mode andit did not seem to make any difference having the stobes with the 5600 flash.
That's because your strobes are firing on the metering preflash instead of the main flash. By default, the camera uses a metering preflash about 100ms prior to the main flash.

This preflash occurs just before the mirror moves out of the way for the main flash. Since your strobes will fire on the preflash, they do not contribute anything to the exposure.

Fortunately, the 7D offers manual power settings to eliminate the need for a preflash. So, set your camera to manual exposure, set your flash control to the desired power (multiple settings from 1/16 to full power) so that your strobes can trigger properly, and take some test photos, changing your settings until you dial in the exposure you're looking for. I think that you can also use manual power settings on the flash itself instead.



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2. If I connect the stobes via a pc cord to the camera and do not use my 5600 flash what settings do I use?
The main variables controlling exposure with a given flash power (camera and strobes combined) are going to be the power of your strobes, Aperture and ISO speed (and of course, subject distance, with diffusers, light modifiers and bounce distances contributing).

Shutter speed makes no difference as to the amount of light the camera sees from the flash. That's because the flash burst is too short (typically from around 1/1000 to 1/20,000 second in duration).

You can use shutter speed to dial in the amount of ambient light contributing to the exposure. For example, if you set your camera to something like f/8, 1/100 second and ISO 200 indoors, ambient light will be contributing virtually nothing to the exposure (your image would normally be very dark without a flash). So, ambient light is contributing virtually nothing. Yet, if you used ISO 400, f/2.8, 1/60 second, you may start to see room lighting contributing to the exposure.

Using smaller apertures and lower ISO speeds at reasonable shutter speeds means that you can isolate your subject from the background easily (closer subject may be properly illuminated by a flash with a darker background because no other light sources are contributing much), and can freeze motion easily (since the subject is only illuminated enough to expose it during the short flash burst).

On the other hand, if you wanted a brighter background from ambient light exposure, you may want to "drag" your shutter more (leave it open longer), and/or increase your ISO speed and/or open up your aperture (smaller f/stop number). That way, light sources other than the flash contribute to the image's exposure (you would get some exposure of these areas if the flash was not being used).

It's a matter of balance.

You will need to have a basic understanding of exposure and experiment with the flash system to get best results in a variety of conditions.

It's not matter of using x,y,x settings for it. There are other variables you have to take into consideration (power of your strobes, diffusers used, aperture, iso speed, distance to subjects, distance/characteristics of areas you're using for bouncing, amount of ambient light you want to contribute, what you want to accomplish from a lighting/shadows perspective and much more).

I'd take some test photos using a variety of settings using manual exposure until you have a better understanding of how the variables involved work.

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Old Oct 8, 2007, 5:02 PM   #3
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For example, set your on camera 5600HS up to a manual power setting of 1/8 power so that your strobes trigger on the main flash instead of the preflash.

Then, start with something like 1/100 second, f/8, ISO 200 and see if your subjects are properly exposed.

If your subjects are too dark, open up your aperture more (go from f/8 to f/5.6 or f/4) to get a brighter exposure and/or increase your ISO speed (go from ISO 200 to ISO 400) and/or increase your power level (go from 1/8 to 1/4 to 1/2 power).

If your subjects are too dark, do the opposite. For example, close down your aperture to a smaller opening (i.e., go from f/8 to f/11) and/or use a lower ISO speed (ISO 100 versus ISO 200) and/or use a lower power level (go from 1/8 to 1/16 power).

After you have a better idea of how the variables you use for controlling flash exposure work, then experiment with letting more ambient light into the exposure using shutter speed and more later.



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Old Oct 9, 2007, 8:53 AM   #4
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JimC wrote:
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... Shutter speed makes no difference as to the amount of light the camera sees from the flash. That's because the flash burst is too short (typically from around 1/1000 to 1/20,000 second in duration). ...
True, though it should be noted that there is a maximum shutter speed that can be used with the flash.

Unless you are trying to use some other light source (daylight, tungsten, ...) with the flash, your best bet is to set the shutter speed to whatever the max sync speed is for your camera and use the aperature/ISO to control the exposure. If you are going to use another light source with the flash, you are likely to have all kinds of trouble getting the white balance uniform without putting filters over the flash units.

As Jim says, use manual settings.
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