Q on metering for Studio Portraits

[smieglitz]

Hi,

I've recently read several contradictory approaches to metering using a flash meter (or incident meter and hot lights) and employing either softboxes or diffusion panels +/- reflectors/subtractors or perhaps a fill light in place of reflector.

I've always adjusted lights to first produce a good lighting effect (whatever that may be in the eye of the photographer) and once the lighting setup is deemed pleasing, a meter reading is made by aiming the (flash) meter incident dome at the camera and setting the camera accordingly. If for some reason a lighting ratio really needs to be determined, a reading from each light alone can be made by pointing the meter dome at the camera from the subject position, taking care to shield the dome from the effect of any other light source (fill or reflector), and the ratio determined.

Others are suggesting that the lights be placed to first produce a specific lighting ratio, determined by pointing the dome at first one light source then the other (rather than at the camera), and then adjusting the ratio precisely by moving the lights or powering the lights up or down as needed. Once the ratio is precisely determined (e.g., 3:1) then the meter is again pointed at the main light source, shielding the meter dome from the fill, and the exposure recommended for the main light alone is used to take the picture. Some advise taking an average between the main and fill lights, again pointing the meter dome at the lights.

The latter two procedures make no sense to me since the effect of the two lights is cumulative. As a result, I would suspect that the reading from the main light alone would cause overexposures. And, taking an average between the two should result in even greater overexposure errors. Also, I don't understand what the point is about aiming the meter at the light source instead of the camera. Pointing the meter at the light source would produce a reading that, if followed, I would think would result in some degree of underexposure. Perhaps these two effects cancel each other out but it sure seems a strange way to do things to me and I would have no confidence in the meter doing it that way.

I've now read these conflicting techniques in several places and have asked a few photographers I know about their use of flash or incident meters and portrait setups, and the responses have varied considerably. Some say meter the main, others say base the exposure on the fill. Some are pointing the meter at the light, others at the camera. Some are setting exposure based on one light, others are taking an average, and some are using the meter reading of both sources simultaneously. Of the two studios where I've worked, meters were rarely if ever used, and if used, were employed just to get in the ballpark. The photographer then either relied on Polaroid to fine tune things or they had already tested their lights by trial-and-error and had marks on the floor where lights should be placed to produce such and such an effect or lighting ratio.

So, I'm wondering what photographers who specialize in studio portraiture do to determine proper exposure?

 

[Jeremy]

I've been told many different ways from pros and the consensus seems to be that there are a number of different ways and as long as the way you choose gives you the results you want then stay consistent.

 

[Ed Sukach]

To determine ratios, I will shut off all light sources except the one in question - then go to the next one - taking incident meter readings from the subject position, with the dome facing (more or less) the camera. Once I know the strength of each source I will calculate the ratios. Another meter reading will be taken with all light sources firing, for overall exposure
Overall exposure could be calculated, but it is easier and more accurate to simplify everything take another reading.

 

[blansky]

The reason you read different ways of doing this is because people do it different ways to get the same results.

I don't think any of it matters as long as you don't underexpose the shadows. When you meter the main and use a reflector as fill, you probably need to get a reading of the fill side to she what your ratios are so you know how close to move the reflector.

If you use a main and a fill light you probably need to meter both and adjust the distance or the power. Since the meter has a dome on it whether you measure towards towards the light or the camera probably won't make much difference.

Another thing to remember is that when you meter the fill side and set the camera for fill, which is usually read from the face of the subject, that you may be underexposing the lower parts of the body because of fall off.

Therefore I usually set the camera at half a stop below the fill light reading or cheat by tweaking the ASA

With negatives, slight overexposure is always better than under exposure.
If you really want to test your setup, read your negs with a densitometer.

Michael

 

[Charles Webb]

Jeremy,
The thumb tack or tape on the floor really doesn't work well because everyone face is not shaped the same and the complexion and skin tone
light to dark has to be considered. With a formula type set up your hands are tied, you must be able to move your lights in and out to compensate for the different skintones. To work out my set ups, I meter the main light,
from the sitters position with only the main light on. Then I turn it off and meter the fill, figure out the placement of the fill in F stops from what your main light indicated. if main reads f11, the the fill should adjusted (moved in or out) to read F8, F5.6, F4. etc to achieve the ratio you want.
To keep your basic exposure constant: Work out your best ratio and exposure.( Polaroid or test exposures) . When you have found what you like,
tape a length of string to the bottom of your main light reflector. With the model in place and the main set exactly where you determined your best
exposure to be pick up the string and streach it to the models chin or nose.
Tie a large knot in the string big enough that you can find it without looking for it. Next with a ruler mark the string with another knot exactly one foot from the first one (towards the lamp) Next do the same with your fill in it's exact spot. Cut the strings close to the first knot. This is what is called a "poor mans" constant intensity meter. Now unlike the mark on the floor you can move your lights any where you want, but will maintain the same exposure by measuring to the subject with your knots. you may also move the camera position. With a dark complected subject move your main in to the the second knot or perhaps half of the distance between the knots for an 1/2 stop increase. For more or less fill do the same. From that point adjust your background light and hair light. Additional lights should be set in
such a way that they have no effect on your main exposure, but are simply placing a unit or two of light to create modeling or spectral highlight. You may also use this technique with table tops (still life) or product shots.

I actually find it much easier to set up the background light before setting the main, you can see it easier on the ground glass.

You will get 100's of answers to your question, and they will probably all work,
I have taught this method for many years, and it does work very well.

 

[blansky]

Wow Charles,

I didn't think anybody was stringing their lights anymore. It's good to hear from an old timer.

Michael

 

[Jeremy]

Jeremy,
The thumb tack or tape on the floor really doesn't work well because everyone face is not shaped the same and the complexion and skin tone
light to dark has to be considered.

Oops! Don't get me wrong, I don't mean to shoot them all the same way. I should have clarified that you should standardize your metering technique so that you know if the fill goes up by this much then this happens or if you always measure pointing at the camera don't start pointing at the light one day because the results will change.