metering when you have multiple lights

Question about metering with my Sekonic L-358. Something I've never been quite able to grasp.

To make it simple, I am using flat lighting...two Nova 22 softboxes at 45 degrees to my subject. I meter the shot at the chin and the exposure comes out as expected.

Now, add a background light. Do I need to meter again?

Now, add a hairlight. Do I need to meter again?

-OR- is metering only needed for the light falling directly on the subject and the power settings on the background and hairlight are merely adjusted for taste?

The answer to your questions is yes, yes, and yes.

Now lets talk about why.

The flat lighting from your two Nova softboxes is your Main light. This controls your exposure on your subjects.

The light from a background light will add to your exposure. You can meter it to match your Main exposure or adjust to taste if you are reviewing each shot on a monitor immediately after taking it. Turn off your main lights while setting up your background exposure. Once you have your background lit the way you want it, meter it so you don't have to hunt for the correct exposure (to suit you) again.

The same with a hairlight. You can meter it to start, but mostly likely (given your question here), don't have a good idea of where to start. Start with trial and error with your main and backlight turned off until you see the hair light doing what you want. Now meter it, and note the stops difference between your main reading and your hairlight reading.

You'll be quicker setting up once you start relating your meter readings to the power settings on your strobes, light modifiers and distance from your subject.

Note: You only need to meter your main exposure if you are using a main and a fill light set at different power levels. In that case, meter them separately to set up your light ratio. Start with either the main or the fill, but be consistent. Do it the same way each time you set up.

canonphotog wrote in post #14711108
The answer to your questions is yes, yes, and yes.

Now lets talk about why.

The flat lighting from your two Nova softboxes is your Main light. This controls your exposure on your subjects.

The light from a background light will add to your exposure. You can meter it to match your Main exposure or adjust to taste if you are reviewing each shot on a monitor immediately after taking it. Turn off your main lights while setting up your background exposure. Once you have your background lit the way you want it, meter it so you don't have to hunt for the correct exposure (to suit you) again.

The same with a hairlight. You can meter it to start, but mostly likely (given your question here), don't have a good idea of where to start. Start with trial and error with your main and backlight turned off until you see the hair light doing what you want. Now meter it, and note the stops difference between your main reading and your hairlight reading.

You'll be quicker setting up once you start relating your meter readings to the power settings on your strobes, light modifiers and distance from your subject.

Note: You only need to meter your main exposure if you are using a main and a fill light set at different power levels. In that case, meter them separately to set up your light ratio. Start with either the main or the fill, but be consistent. Do it the same way each time you set up.

I'm missing something here. You can only enter one setting into your camera, so how do you account for multiple meter readings? Wouldn't you put all your lights on and then meter your subject with one pop?

canonphotog wrote in post #14711108
The light from a background light will add to your exposure. You can meter it to match your Main exposure or adjust to taste if you are reviewing each shot on a monitor immediately after taking it.

So you mean to keep adjusting the background light setting until my meter reading with just the background light (just in from of the backdrop) gives me the same aperture value as when I metered my main lights in front of my subject?

canonphotog wrote in post #14711108
The same with a hairlight. You can meter it to start, but mostly likely (given your question here), don't have a good idea of where to start. Start with trial and error with your main and backlight turned off until you see the hair light doing what you want.

So what is the point of metering the hair light? Is the purpose only to adjust to the power setting so it is relative to the main light?

canonphotog wrote in post #14711108
Now meter it, and note the stops difference between your main reading and your hairlight reading.

And that will tell me what?

canonphotog wrote in post #14711108
You'll be quicker setting up once you start relating your meter readings to the power settings on your strobes, light modifiers and distance from your subject.

I can only hope.

canonphotog wrote in post #14711108
Note: You only need to meter your main exposure if you are using a main and a fill light set at different power levels.

Huh? If I didn't meter I wouldn't know what aperture to use (even with flat lighting)?

Wow, didn't expect to provide confusion.

Let me re-read your responses to my answer and see if I can be a bit more clear for you.

canonphotog wrote in post #14711335
Wow, didn't expect to provide confusion.

Let me re-read your responses to my answer and see if I can be a bit more clear for you.

I'm not exactly the sharpest knife in the set.

coeng wrote in post #14711293
So you mean to keep adjusting the background light setting until my meter reading with just the background light (just in from of the backdrop) gives me the same aperture value as when I metered my main lights in front of my subject?

Yes. This ensures your background is brighter or darker than your main exposure. The caveat is., sometimes you want the background darker, sometimes lighter. You will need to adjust for that when you want it either way.

coeng wrote in post #14711293
So what is the point of metering the hair light? Is the purpose only to adjust to the power setting so it is relative to the main light?

Essentially, yes. But that isn't the only reason. If you have time to set up you hairlight and dial it in, you should do that with the main lights and background lights off. The goal here is to only see the light contribution from the hair light so you can control it. Eventually you will want to use a grid on your hairlight to control light spill and keep from putting light places in your photo that you don't want it.

coeng wrote in post #14711293
And that will tell me what?

It will tell you the difference between the two, in stops of light. That way once you know what you like, you can set the hairlight output based on the difference between it and your main light output. You won't always be at f/8 and 1/125th of a second. When you change your main, you'll need to change your hairlight.

coeng wrote in post #14711293
I can only hope.

coeng wrote in post #14711293
Huh? If I didn't meter I wouldn't know what aperture to use (even with flat lighting)?

Okay. I definitely was not as clear here as I should have been.

There are several ways to meter main and fill lights. One is to meter your fill light first, then after it's where you want it, turn it off, turn on the main light and meter it. Next with both the main and the fill light turned on, meter from under the chin of your subject. You will find you have more light than expected, but it will not cause a problem. Just use that setting for your camera.

Some folks get wound around the axle when studio shooting and only want to shoot at f/8 and 1/125th of a second, (your iso here). If you're like that, leave your main off, turn on the fill and meter to something like f/5.6, f/4 or f/2, then while leaving the fill light on, turn on the main and meter from under the chin until you get f/8. You now have a light ratio of your choice dialed in.

Whether the light on your subject is flat or ratio'd, you will need to meter it.

Apologies for the confusion.

canonphotog wrote in post #14711416
Some folks get wound around the axle when studio shooting and only want to shoot at f/8 and 1/125th of a second, (your iso here). If you're like that, leave your main off, turn on the fill and meter to something like f/5.6, f/4 or f/2, then while leaving the fill light on, turn on the main and meter from under the chin until you get f/8. You now have a light ratio of your choice dialed in.

Another option for this is to meter the light separately to get the ratio you want, then turn them both on and meter again. As indicated previously the reading will be higher... adjust both lights down by the same amount (e.g. 1/3-stop at a time, on both lights) until you get to the aperture you want to shoot at.

canonphotog wrote in post #14711416
Yes. This ensures your background is brighter or darker than your main exposure. The caveat is., sometimes you want the background darker, sometimes lighter. You will need to adjust for that when you want it either way.



Essentially, yes. But that isn't the only reason. If you have time to set up you hairlight and dial it in, you should do that with the main lights and background lights off. The goal here is to only see the light contribution from the hair light so you can control it. Eventually you will want to use a grid on your hairlight to control light spill and keep from putting light places in your photo that you don't want it.

It will tell you the difference between the two, in stops of light. That way once you know what you like, you can set the hairlight output based on the difference between it and your main light output. You won't always be at f/8 and 1/125th of a second. When you change your main, you'll need to change your hairlight.





Okay. I definitely was not as clear here as I should have been.

There are several ways to meter main and fill lights. One is to meter your fill light first, then after it's where you want it, turn it off, turn on the main light and meter it. Next with both the main and the fill light turned on, meter from under the chin of your subject. You will find you have more light than expected, but it will not cause a problem. Just use that setting for your camera.

Some folks get wound around the axle when studio shooting and only want to shoot at f/8 and 1/125th of a second, (your iso here). If you're like that, leave your main off, turn on the fill and meter to something like f/5.6, f/4 or f/2, then while leaving the fill light on, turn on the main and meter from under the chin until you get f/8. You now have a light ratio of your choice dialed in.

Whether the light on your subject is flat or ratio'd, you will need to meter it.

Apologies for the confusion.

Okay I think I got it. Once you have your main/fill f-stop that's your "point of reference." Turn it/them off, and adjust background like until you like it. Meter that and make a note of the difference between it and the f-stop for main/fill. Because if you change your main f-stop again, you'll need to change you background light again until it has the same differential as it originally did. Ditto for the hair light, right?

For my hairlight I'm actually using a snoot because I don't own grids (just ordered them today as a matter of fact). My background light doesn't have any type of diffuser on it, just the reflector. Until my grids arrive, is there anything around the house that I can use to reduce the power of my background light. Even at its weakest setting, it is really putting a lot of light on my backdrop because its on a floor stand about 3 feet away from backdrop. See this thread I started earlier today for my configuration.

Thank you again. You have been most helpful.

coeng wrote in post #14711015
-OR- is metering only needed for the light falling directly on the subject and the power settings on the background and hairlight are merely adjusted for taste?

This

I always start with my fill light. If I know I want my fill light to be three f stops under my key and I know I want my key to be f/8, then I meter my fill for 2.8. If I wan't two f stops, I start at f/4 with my fill, and so on.

Hair and background are to taste, however, if you want repeatable results that looks good for things like directories and yearbooks, then I meter to the hair light to match my key, measured from the crown of the head, and my background light to match my key at shoulder height.

After all that I kick my key on and meter f/8. If I had started with the key at f/8 then added a 2.8 fill, I wouldn't have f/8 anymore. More like f/10. The light is additive.

^^^

What he says. Figure out what you want your ration to be and start with fill.

bdillon wrote in post #14712096
I always start with my fill light. If I know I want my fill light to be three f stops under my key and I know I want my key to be f/8, then I meter my fill for 2.8. If I wan't two f stops, I start at f/4 with my fill, and so on.

Hair and background are to taste, however, if you want repeatable results that looks good for things like directories and yearbooks, then I meter to the hair light to match my key, measured from the crown of the head, and my background light to match my key at shoulder height.

After all that I kick my key on and meter f/8. If I had started with the key at f/8 then added a 2.8 fill, I wouldn't have f/8 anymore. More like f/10. The light is additive.

Wow. That is exactly what I've been looking for! Simple and to the point.

bdillon wrote in post #14712096
I always start with my fill light. If I know I want my fill light to be three f stops under my key and I know I want my key to be f/8, then I meter my fill for 2.8. If I wan't two f stops, I start at f/4 with my fill, and so on.

Hair and background are to taste, however, if you want repeatable results that looks good for things like directories and yearbooks, then I meter to the hair light to match my key, measured from the crown of the head, and my background light to match my key at shoulder height.

After all that I kick my key on and meter f/8. If I had started with the key at f/8 then added a 2.8 fill, I wouldn't have f/8 anymore. More like f/10. The light is additive.

I think I am following this correctly, but I'm either missing something, or I dunno...

If you want a 2-stop difference between your fill and key lights, you want your fill to be at f/4, and you want to shoot at f/8. You start by metering your fill light until you get it at f/4. Next, you add your main light, and adjust until your meter reads f/8. Am I correct in saying that you actually don't have a 2-stop difference? Because, what you have metered is the combination of your fill and your key to get to f/8, so the key light is actually less than f/8... right?

go here
http://super.nova.org/​DPR/Ratios/