How to reduce flash power

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Neutral density gels over the flash heads, the problem with that is that it will dramatically reduce the effective power of the already inadequate modelling lamps too.

Or a neutral density filter over the camera lens. The problems with that is that it will increase the risk of flare, and with some lenses may also affect the autofocussing.

ND filters and gels are commonly available in 1, 2, 3 & 4 stop variants. I suggest 2 stop (0.6) min and 3 stop (0.9) max
 
Ivan S said:
Smaller aperture? faster shutter an option?
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Hi, A smaller aperture will not reduce the power of the flash, it will only reduce the amount of light from the flash getting to the sensor/film. Not the same thing as you may need or want to use a larger aperture. You could try using a N/D filter on your lens, this will enable you to use a larger aperture if needed.

A faster shutter speed will have no effect on the exposure if the subject is lit only by electronic flash. And if the camera you are using has a Focal Plane Shutter then increasing the shutter speed too much will cause part of the image to be cut off.

The only way to reduce the amount of light from the flash is to reduce it at source ie with lowering the power switch on the flash which you have already tried or using N/D gels in front of the flash head. You could also try bouncing the flash into an umbrella, but of course this will give you much less control of the type of light you want for the subject. Hope this helps.
 
G.K.Jnr. said:
Hi, A smaller aperture will not reduce the power of the flash, it will only reduce the amount of light from the flash getting to the sensor/film. Not the same thing as you may need or want to use a larger aperture. You could try using a N/D filter on your lens, this will enable you to use a larger aperture if needed.

A faster shutter speed will have no effect on the exposure if the subject is lit only by electronic flash. And if the camera you are using has a Focal Plane Shutter then increasing the shutter speed too much will cause part of the image to be cut off.

The only way to reduce the amount of light from the flash is to reduce it at source ie with lowering the power switch on the flash which you have already tried or using N/D gels in front of the flash head. You could also try bouncing the flash into an umbrella, but of course this will give you much less control of the type of light you want for the subject. Hope this helps.
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George,

I guess you should take a look of the kit the OP bought, since I presume you are talking about speedlites . ;)
 
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PitaDaVespa said:
George,

I guess you should take a look of the kit the OP bought, since I presume you are talking about speedlites . ;)
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He's talking about flash, full stop. And what he says is correct
 
PitaDaVespa said:
George,

I guess you should take a look of the kit the OP bought, since I presume you are talking about speedlites . ;)
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Hi, With respects to you I did take a look at the kit the OP bought, how else could I reply efficiently to the question ?

I'm talking about Studio Flash which I use virtually every working day using the various things I suggested. Speedlights are a totally different thing.
 
G.K.Jnr. said:
Hi, With respects to you I did take a look at the kit the OP bought, how else could I reply efficiently to the question ?

I'm talking about Studio Flash which I use virtually every working day using the various things I suggested. Speedlights are a totally different thing.
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Sorry, my fault. English is not my main language and sometimes... :\
Please, don't take me wrong.

Regards,
Luis
 
This is actually my first go so im sure I am doing something wrong.

What I am trying to do is to take a picture of my daughter with the backround completley white.

At first I used both strobes and they were behind the model. I found that even though the background was completly overexposed my daughter was also nearly overexposed because of the light falling on her back.

I could have moved her a bit further feom the background but the room is so small that my 100mm will be too long. The ceiling is also not very high so some of the light is also probably bouncing of the ceiling.

I switched off one of the strobes and using just one was also too powerfull. I thought the power of the flash could have been set to near 0 but when set at 0 or minimum it is also still too strong.

I have a 580ex II. Is it not possible to control the power of these strobes using the 580ex?

I will try the ND gels as suggested to see if that will help.

I am at work at the momemt but will post some examples of the setup and the room when I get back home.

Ps. Sorry for the typos im using the phone to type. :)
 
Completely white back ground just set the rear flash head one stop more than the key. You should only need one light for this.
Bring you ISO all the way down 100 or less and use a high Fstop F22
 
A completely white background is difficult to do well, especially in a small room with a low, white ceiling - do you really need to shoot against a white background?
If you can live without the white background, your problem will probably go away, or at least to a large extent. If you really can't live without it, then you need to light the background JUST enough to make it white, which is generally less than 1 stop more light than is used on the main subject.
Do NOT set your lens aperture to f/22, your camera is perfectly capable, but it has a cropped sensor and you will start to lose sharpness if you reduce the aperture beyond f/11 - google diffraction limitation for an explanation of this.

I'm guessing that those lights just don't adjust down by anywhere near the 3 stops claimed for them. In fact they probably don't adjust down very much at all. That being so, your only real solution is as I suggested earlier - neutral density gels or a neutral density filter over the lens.
 
What Garry said about the flash power! However, using the softbox to light the background from as far away as practical should get you somewhere close to a reasonable exposure at ISO 100.

Your biggest problem really is the space you're working in.

Small spaces require more precise lighting control, this is one of those occasions where you're really stacking the odds against yourself.
  • Shooting a portrait in a small room - fairly easy
  • Shooting a portrait against a white background - fairly easy
  • Shooting a portrait with those lights - fairly easy
  • Shooting a portrait with a 100mm lens - fairly easy
  • Shooting a portrait in a small room against a white background with a 100mm lens with those lights - difficult.

A bigger space so that you can control the lighting, a shorter lens, a better choice of background are all things that'll make life easier.
 
Phil V said:
Your biggest problem really is the space you're working in.

Small spaces require more precise lighting control.
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When i first started to play around with studio lights in my spare room this was always my problem, i had a white ceiling and cream walls, so inevitably shooting against a white background would have light bouncing all over the place, one of the things i did to combat this, was to fix some black material to the ceiling and the walls around the background, to stop the bounce and it did help quite a bit, you will get it in time with practice and with some trial and error. If you are going to be using a white background in small spaces on a regular basis, you may want to think about investing in a Lastolite Hi-lite :)
 
Ivan S said:
Smaller aperture? faster shutter an option?
Click to expand...

Shutter speed will not result in a reduced exposure of a flash unit unless the o/p has way too much ambient light impeding the shot. Aperture and ISO will affect the exposure. Too fast a shutter speed will result in the rear curtain banding on the shot, but not reduce the intensity of the flash power.

To the o/p, assuming this is off camera or studio lighting flash, make sure your ISO is set to the lowest your camera can muster 100 or 200) and close your aperture down to something like f/11. Is your shot still overexposed?
 
If using the softboxes only, would it be possible to use velcro and add an additional layer of white to the front of the softbox, That should reduce the output by a stop or two?
 
alexam said:
If using the softboxes only, would it be possible to use velcro and add an additional layer of white to the front of the softbox, That should reduce the output by a stop or two?
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That's a popular belief.
But in reality, an extra layer of diffusion doesn't so much reduce the amount of emitted energy as spread it over a larger area..

Spreading it over a larger area does mean that a little less light would reach any specific part of the subject (how much effect this would have would depend on the distance travelled by the light) but this can create its own problems.
 
The strobes the OP bought only go down to 1/8. Therefore I would have thought an ND filter might help.
 
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