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I was trying a few things yesterday involving a studio backdrop which was lit using a grid to provide a gradient effect and a subject about 3ft in front of it, with its own lighting through umbrellas.

I was having problems with the shot being over-exposed. I had my studio lights on the lowest possible power setting, ISO-100, a shutter speed of 250 (the max sync speed) and my aperture was f/22 which is the highest it will go.

I don't really want to have to use the highest possible aperture value, and would like a bit more room to adjust it. The background was so detailed that you could see the paper texture which would had been better blurred out slightly.

Is there any way that I can further adjust the light input so that I have more flexibility with my settings?

  • An offtopic comment but an important one. On a portrait photography you need to take care of your client's eyes. If you are shooting a verey intense light you can harm the retina. So I think it is important to lower your settings. Turn on an ambient light too. If your flash head has a model light turn it on, so the pupil is closed. – Rafael Mar 23 '15 at 17:08
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    ND filter is the obvious answer. Very useful for studio shots like this. – dpollitt Apr 23 '15 at 0:40
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I think the approach will depend on several things: if the light is soft or harsh, if the overexposed illumination is over the entire scene or just a part of it.

ND Filter

If the entire scene is lit then you can try using a ND filter. If you use a 4x ND filter you can reduce the exposure from f22 to f11 or with an 8x to f8. A polarizing filter will also cut light if you don't have reflective surfaces or already polarized light.

Soft light

You can try using ND gel filters for the lights. You can also use wax paper to lower the light on individual strobes. Put the paper or gel over the flash head. Just be careful to ensure that the paper you are using doesn't change your white balance.

Harsh light

You can use a cardboard of black paper to make a mask on the light and move your lights further away. Twice the distance = 1/4 the light. Use the cardboard to maintain a similar shape regardless of the light distance.

The gel flash filters can also work but probably can scatter the light a bit. The wax paper option will diffuse it, but it is still an option if you have a considerable distance to your subject.

The cheaper way

Just put your lights further away.

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At ISO 100, f/22, and 1/250 of a second, your light would have to be brighter than daylight. This is highly dubious. The first thing you should do is check that those numbers are correct.

Setting your lights lower should be easy. Knowing what make/model of lights you have might be helpful. Its likely you do not have them at the minimum setting if they are brighter than sunlight. Most will go down to around 50-100 WS at the low end.

Are you sure you have the camera ISO set at 100 and the lights at minimum?

By the way, increasing the shutter speed is not going to affect exposure much from the strobe, it will only reduce the continuous/ambient light.

I'm not sure what size your umbrellas are, but you generally do want to keep them close at a low setting, rather than far at a high setting. That said, if your umbrellas are just a couple of inches away from the subject, that might explain the high output.

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Well, if you're using monolights, backing down to speedlights might be the best way to reduce power, particularly since you're working with a subject so close to the backdrop. If you're working with the lights in very close, say for macro/food/product shooting, possibly switching out to LED panels would make even more sense.

The second thing to try would be to separate the subject from the backdrop by, say, 10' if you have the space, to make sure the background light is not spilling over onto your subject and causing the overexposure. Since you're already gridded, this should help, but you may want to consider flagging off as well.

You could use an ND filter on the camera lens, or on the lights to reduce the light.

And there's always the inverse square law--doubling your distance would give you 1/4 the light; tripling would give you 1/9th. Moving your lights farther away from the backdrop and subject might help, although, of course, this will make the light harder.

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You will think this is crazy but -- you can dot your camera lens with black wax pencil. If you are afraid, mount a UV filter and dot it with wax. The dots will not image, they will reduce the light transferring the lens. You can cover the lens with aluminum foil. Pierce the center with as sewing needle. You are making a pin-hole that acts as an additional iris (aperture). You can experiment with different size holes.

The dotting of the lens is more legitimate than you might think. It is common practice in photofinishing to dot sets of lenses to fine tune them so they expose identically as to exposure intensity. Practiced in school finishing when cluster lenses are used to make packages of prints, you know, 8 wallets or 16 sub-wallets on a single piece of paper all exposed at the same time.

I know, ND filter is best but ---

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