Lighting Ratio Help

Can someone tell me if I have the concept in mind correct?

1. Fill light should be set two stops less than main light as a starter

2, So...using L 358 Flash meter I set my ISO on the meter, trip flash and reduce power until I get the f stop i want, say 4.


3. Go to fill light, trip and read with meter, reduce power until i get F 8 (two stops less light than the main light).

4. Now, what do I set the camera at? F4 so I have the depth of field I want on the subject, or, do I read the flash by firing both flashes at the same time and reading with light meter?

interested on this too...subscribing.

I'm no expert, but I'll take a shot at this. First, a 2:1 or 3:1 ration of key:fill is a good place to start. Now most studio shooting is done at f8 or f11 or even higher f-stops. But if you want to shoot at ISO 100, f4, and 1/200 shutter speed, then you want your meter to read exactly this when both main and fill lights fire. So you'd probably meter the fill light alone first to get a reading at 2-stops lower than your desired aperture. Then add the key light and adjust the power until you get the reading you want to shoot with. You may have a hard time shooting at f4 with two lights, depending on the lights (too much power at even the lowest settings).

DarenM wrote in post #8710360
Can someone tell me if I have the concept in mind correct?

1. Fill light should be set two stops less than main light as a starter

2, So...using L 358 Flash meter I set my ISO on the meter, trip flash and reduce power until I get the f stop i want, say 4.


3. Go to fill light, trip and read with meter, reduce power until i get F 8 (two stops less light than the main light).

4. Now, what do I set the camera at? F4 so I have the depth of field I want on the subject, or, do I read the flash by firing both flashes at the same time and reading with light meter?

If your main light is at f/4, then your fill should be at f/2 if you want 2 stops less light for fill relative to the main light. f/8 means that the fill is brighter than main by 2 stops.

To determine the shutter speed your camera should be set to, measure the light with both strobes/flashes turned on. The meter should read f/4 or a little over that.

DarenM wrote in post #8710360
Can someone tell me if I have the concept in mind correct?

1. Fill light should be set two stops less than main light as a starter

2, So...using L 358 Flash meter I set my ISO on the meter, trip flash and reduce power until I get the f stop i want, say 4.


3. Go to fill light, trip and read with meter, reduce power until i get F 8 (two stops less light than the main light).

4. Now, what do I set the camera at? F4 so I have the depth of field I want on the subject, or, do I read the flash by firing both flashes at the same time and reading with light meter?

You're confusing smaller apertures with less light. If you have one light giving you a meter reading of f/8 then decreasing the amount of light by 2 stops would give you a reading of f/4, which is a larger aperture. If the aperture were to be 2 stops smaller (higher number is smaller aperture) that would be f/16 which would require 2 stops more light.

This concept is easily misunderstood but very important for understanding exposure and how it pertains to quantity of light and aperture.

Some pretty good info in the sticky thread on ratios.

The ratio of the fill light is relative to what you trying to achieve. If your metering is f/4 for the main light, set your camera to f/4 and take a pix and chimp to make sure the main light is correct.
I usually start my fill light at half the main light and adjust accordingly depends on the subject and mood. There plenty of guidelines but no set rules.

vincent_su wrote in post #8711341
The ratio of the fill light is relative to what you trying to achieve. If your metering is f/4 for the main light, set your camera to f/4 and take a pix and chimp to make sure the main light is correct.
I usually start my fill light at half the main light and adjust accordingly depends on the subject and mood. There plenty of guidelines but no set rules.

Sorry, but when discussing lighting ratios, chimping shouldn't even come up. Histograms and chimping don't tell you anything about ratios.

TMR Design wrote in post #8711353
Sorry, but when discussing lighting ratios, chimping shouldn't even come up. Histograms and chimping don't tell you anything about ratios.

I was answering OP's question about how to setup camera.
The chimp is just to double check if the lighting from main light is correct because I don't have a light meter. Hope that clears this part.
As for the ratio, I've also stated that I start with 1/2 of the main light and adjust accordingly.

TMR Design wrote in post #8711353
Sorry, but when discussing lighting ratios, chimping shouldn't even come up. Histograms and chimping don't tell you anything about ratios.

AGREEEEED!!! This is so true, and so often overlooked or forgotten or dismissed.

vincent_su wrote in post #8711436
I was answering OP's question about how to setup camera.
The chimp is just to double check if the lighting from main light is correct because I don't have a light meter. Hope that clears this part.
As for the ratio, I've also stated that I start with 1/2 of the main light and adjust accordingly.

If you don't have a light meter then how are you adjusting? Half the power of the main light only means something if you can meter it.

Here is how I do it. I start with settin my camera in M mode, pick an aperture that can cover the focus of my subject, set the ISO, usually 100, then I use 1/250 SS for a test shot. I have my main light starts at 1/4 power and look at the pix and chimp just to make sure.
Then, I would fine tune between the aperture and light output. Once the main light output is what I want, I set the fill light at 1/2 the power of my main light.
This sequence has worked well for me for head shots and product shots.
If there's an easier way, I'll be more than happy to learn.

vincent_su wrote in post #8711496
Here is how I do it. I start with settin my camera in M mode, pick an aperture that can cover the focus of my subject, set the ISO, usually 100, then I use 1/250 SS for a test shot. I have my main light starts at 1/4 power and look at the pix and chimp just to make sure.
Then, I would fine tune between the aperture and light output. Once the main light output is what I want, I set the fill light at 1/2 the power of my main light.
This sequence has worked well for me for head shots and product shots.
If there's an easier way, I'll be more than happy to learn.

Easier way is to have a light meter when talking about ratio. I totally agree with Robert.

vincent_su wrote in post #8711496
Here is how I do it. I start with settin my camera in M mode, pick an aperture that can cover the focus of my subject, set the ISO, usually 100, then I use 1/250 SS for a test shot. I have my main light starts at 1/4 power and look at the pix and chimp just to make sure.
Then, I would fine tune between the aperture and light output. Once the main light output is what I want, I set the fill light at 1/2 the power of my main light.
This sequence has worked well for me for head shots and product shots.
If there's an easier way, I'll be more than happy to learn.

You're missing the point. The OP wants to know how to meter and set ratios. What you're doing is guessing and you have no way of knowing what the ratio is between main and fill. The power levels are meaningless. I'm not saying that you're not getting the results you want but you're not establishing ratios based on anything more than guesswork.

TMR Design wrote in post #8711523
You're missing the point. The OP wants to know how to meter and set ratios. What you're doing is guessing and you have no way of knowing what the ratio is between main and fill. The power levels are meaningless. I'm not saying that you're not getting the results you want but you're not establishing ratios based on anything more than guesswork.

You are SO right Robert. Chimping your way there is not the right way to teach ratios or learn them.