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Old Aug 18, 2008, 3:54 PM   #11
JimC's Avatar
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Location: Savannah, GA (USA)
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Just to make sure you're not overlooking the obvious....

You do have your ISO speed set to a low value, right (versus letting the camera select it using Auto ISO)?

Each time you double the ISO speed, flash range increases by 1.4x for any given aperture setting. So, I'd double check to make sure it's set to lowest available value. In a darker environment, the camera's Auto ISO is probably dialing it up to a higher value.

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Old Aug 19, 2008, 3:48 AM   #12
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Hi JimC

Yep, I have the ISO dialled down to 100...the lowest the 40d will go.

I am now thinking of this light meter: http://www.sekonic.com/products/Seko...H%20MASTER.asp


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Old Aug 20, 2009, 12:59 AM   #13
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Default Bla, bla, bla

You have given us a few too many variables in one question but here goes.

I think Bob has the best solution (simple & cheap) with the ND filter(s).

But just so it SEEMS like I’m smart…

It looks like you are using an umbrella with a black backing, if removable try that, then turn the umbrella around and shoot through it.

That will give you three different pics, 1. Shoot-through 2. Bounce w/backing 3. Bounce w/o backing. Figure out which one gives you the least amount of light also remember which one gives you the most light. I know this will change your ability to control light bouncing around the room but a black “reflector” or a gobo will kill any fill.

Pause – I just noticed you used the term “brolly” after the word umbrella??? You can figure it out.

You can also change the output by changing the distance between the umbrella and the flash. When shooting through, the further the light is from the umbrella the less light you will get, but when bouncing it will depend on the shape of the umbrella. Please refer to white lighting.com under Parabolic Light Modification System for a short but good lesson with diagrams.

I would avoid a snoot or honey comb grid because they will fix the angle of your light output that can only be changed by changing the distance to the subject, something you indicated would be a problem for you. There is also the problem of your subject moving just a few inches and then the light misses them all together.

Remember the quality of the light will also change, a snoot or grid will be a “harsher” light than any diffused light source (umbrella/box/brolly).

If you want to try a snoot build your own with a piece of art board and the tube from a roll of toilet paper. You can change the angle but cutting the length of the snoot.

Last week I was helping a photog with some wedding portraits and the background light was too bright. Working from an old style power pack, with that isolate/combine/symmetrical/asymmetrical-crap, limited my ability to adjust that one light without affecting the other three lights so I grab a piece of typing paper, taped it over the reflector – problem solved. You might try something that simple - just turn off the modeling light to avoid any fires.

I’ve used vellum, works fine!

You added a new problem by wanting to lighten the background. Same rules apply (inverse square law of light). But you might be able to modify the background light with a white or silver reflector below and behind your subject that captures some of the main light and reflects it on to the background.

I see no real need for a light meter. Since you can’t move your lights much and you can check exposures on your camera that money could be better spent elsewhere. But that is a personal choice. I seldom use my Sekonic flash meter
in studio because I don’t move the lights much. I use it more on location where both the ambient light and flash output varies.

Good luck - Africa
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