flash power.

andy owen

andy owen

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Name
Andy
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Hi all,

Ive got an Interfit 150 studio kit. It has 2 units with 2 soft boxes. Each unit has a 150w modelling light in the centre surrounded by the flash tube.
I can turn down the modelling bulb to modify a shot but what I cant alter is the flash. So in cases where I set up at someones house and there is not a huge amount of space the images can appear to be blown out. Ive tried speeding up the shutter speed to 320 but at this point you can start to see the 2nd curtain at the bottom of the image. Im thinking of buying some umbrellas which would soften the light by turning the lights away from the subject unless someone can advise me on how to correct this issue?


Cheers
Andy
 
When using flash you keep the shutter speed below the curtain sync speed and then use the aperture to control the amount of light getting in.

the larger the aperture the more light (f2.8 etc) and as the apertures get smaller and smaller (f8, f11 etc) it lets less light in.

So if your photos are blown, you need to decrease the size of the aperture and it should sort it out. Be aware though that this will also effect the depth of field.

I'd be surprised though if you couldn't adjust the flash power of the flashes themselves on the actual units.
 
Last edited:
Shutter speed has no influence over the power of the flash gun

Aperture does that. Or distance of the flash gun from the subject. So, if you are burning out images at say f8 use a smaller aperture, say f11 or f16.

Alternatively move the flash away from the subject.

Alternatively, lower the setting of your ISO. So if you are shooting at ISO 400, reduce it to 100.

Or, add a neutral density filter in front of your lens.

anything you don't understand, please feel free to ask again :)
 
String and HN, youve both explained it well, thanks, ill try that in future. On my latest attempts I used shutter priority at 250, but after looking at the exifs the aperture says it shot at f4. I will use manual in future.
I reduced ISO to 100 and even decreased the exposure to -1 but some of the shots were still blown. The one thing I didnt know about was that aperture controls the light!! thanks guys.

Incidentally, with regard to HNs post "I'd be surprised though if you couldn't adjust the flash power of the flashes themselves on the actual units."

There are 2 controls on the rear of the units one switch with "I" and "II" and a knob which can be turned. When "I" is selected the modelling light can be adjusted with the knob. When "II" is selected the modelling light cannot be adjusted. The flash seems to remain the same throughout with no power change

Andy
 
ouch!
You weren't shooting in manual? Bad Idea. Shoot in manual. Let me suggest something!

Select 1/125 F11. Try that for your starter. If its too dark open by one stop at a time.

And save for a flash meter :)
 
The "I" is normally where you can not change the output of the modelling light and the "II" is where you can change the modelling light and then use the turny knob to adjust the power and bare in mind that the output of the modelling light is the same flash output so if you modelling light is on full output then your flash will be thus causing the overexposure.
 
ND filters?
or
flash power controls
 
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