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2.2 Incident Light Metering

Incident light metering is what you are going to use for just about all of your product shots. In this lesson you will find out how it works and how to make it work for you!

2.2 Incident Light Metering

Incident light metering is what you are going to use for just about all of your products shot. In this lesson, you'll find out how it works and how to make it work for you. In the last lesson, you learned that cameras cannot meter the light from a manual flash. In order to accomplish this, you need a light meter that can measure flash. This is the Sekonic L-308S flash meter and it's a fantastic basic flash meter. There are fancier meters out there with more features, but this little guy will do just about everything you will need. With this meter,you can measure the light from any strobe or speed life as well as constant lighting sources. This meter can measure reflected light and incident light. Incident light metering measures the light that is falling on an object. In this case, it measures the light that's hitting this lumisphere. Oftentimes, this is more accurate than reflective metering. Because incident light metering doesn't see how reflective an object is, it only sees how much light is hitting that object. It also gives us something that a camera can't do. And that is the ability to meter flash. On this meter, there are two modes for metering flash. The first is called auto reset cordless flash, which I know is a mouthful. When the meter is in this mode, you press the measure button and the meter waits for ninety seconds for a flash pulse. When it sees a flash pulse, it measures the light, displays the measurement, and waits again for another flash pulse. The other metering mode is cord flash mode. In cord flash mode, you attach a sync cable from the meter to your flash unit. And when you press the measure button the meter triggers the flash and takes the reading of the light. The metering of the flash works exactly the same in both of these modes. The only difference is how the flashes are triggered. In auto reset cordless flash mode you trigger the flashes and in cord flash mode the meter triggers the flashes when you press the measure button on the side here. I find auto reset cordless flash mode the most convenient to use, but not the most convenient to say. Let's look at how to use the meter to get a basic exposure. All right, I have my camera set up here and I have an off camera flash that's in manual mode. This is actually a TTL flash, but I have it in manual mode and that's going to work exactly like any other manual speed light. I'm going to shoot a photo, here, of this old DSLR camera. But I need to figure out what my camera settings should be, and what I need to put the flash on in order to get the appropriate exposure. And like we talked about before, that's going to be impossible to do without taking multiple test shots in adjusting the settings on the camera. And the settings on the flash. But with the flash meter here, we can do that very very quickly. So first, I'm going to want to turn the flash meter on. And I'm going to put it in auto reset cordless flash mode which is right here. And then, I need to set up my camera so it matches the settings on the meter. So right now my meter is set to ISO 100 which is usually what I like to be at when I'm shooting with flash. It's also set to shutter speed of 250. Which is my camera's sync speed. The sync speed is the fastest shutter speed you can use when your sensor is fully exposed. And on this camera system it's 1/250th of a second. So I need to input these settings into my camera, so I'm gonna change the ISO to ISO 100, and I'm gonna change the shutter speed 1/250th of a second. Now my aperture is still at F5 on my camera. I don't know if that's appropriate with what this flash is set at here, so I need to take a meter reading. So right now the flash is set to 1/32nd power. I'll just show you, 1/32nd power. And I want to leave it says right here so that I don't move the flash because at this distance if I move the flash in a little bit it, may effect the exposure because the light is really close. So I'm gonna put my meter in the same space as my subject. And I'm going to point the meter in the lumisphere Which is this guy right here in the direction of the lens. I need to have it pointing in the same direction as the camera's lens. So I'm gonna press measure. And the meter is going to wait for a flash pulse. So I'm gonna fire off the meter and I get a value of F10. So, if I put F10 In my camera here. And I take an exposure. The exposure should look pretty good. Now is it a great looking shot? No, not really. This is a hard light and it's perhaps not the most flattering. But the point is the exposure looks good. And that's really all there is to it. I put the meter in the same space as my subject. I point the lumisphere down the barrel of the lens. And I take a meter reading. At this flash power, which is 1/32nd power, it's giving me F10 as a value. Then I put those settings into my camera and I take a shot and I'm good to go. Now let's say we wanted to use a different aperture. Maybe you wanted to use F8 or F4. Well, what we need to do in this case is turn down the power of the flash. So, if I go down to 1/64th power without moving it and I re-meter Now it's giving me F8. So if I put F8 into my camera, and I take another shot. [SOUND] That exposure and the previous exposure should look really close. Actually, it looks a little bit brighter, let me take another meter reading here. It says F7.1, so it may be that the flash needed to discharge once. So let me put F7.1 in. [SOUND] So now this shot should look very, very similar to the exposure on the previous shot. And if for whatever reason you wanted to use a larger aperture. So maybe you want it to use F4. What you need to do Is turn the flash down even more. So if I turn it down all the way, which is one 28th power, I get F5.6. So at this distance and with this particular speed light. I can't get F4. It's impossible because the lowest power on this flash is 1/128th power and so I can't get F4. What I'd have to do is take the flash and move it farther back. So let me re-meter now that the flash is pulled back. And now I'm getting F4. So if I put this into the Take another shot. [SOUND] That exposure, overall, should look pretty similar to the previous exposure. Now, because the light got moved, it's not going to look exactly the same. But the overall exposure on the camera should be very, very similar. Now if I wanted to use an even larger aperture, something like F2.8 or F1.4, I have to move the flash farther back or I'd have to use some kind of light modifier like a diffuser, which will knock down the power and change the like quality of the flash to get down to F2.8. Now I can actually do that very easily just to show you by bouncing the flash off the ceiling. So if I just put this flash back where it was, and I point the flash head straight up at the ceiling, and I take another meter reading here. It's going to give me a reading of F1.4. Now this lens can't go down to F1.4. So I'm going to have to turn up my flash here. I've now turned dit up to 1/4 power. And let's take a meter reading or here. I'm getting F3.2. So let's turn it down to 1/8th power. That's says two 2.5. So I need to come up just a tiny bit. So I'm gonna go up to 1/8th plus 1/3rd stop on the flash here. And that's giving me F 2.8. So if I put that in my camera and I take a shot. You see that the exposure is going to look great. Now it's obviously a completely different shot because the quality of light is much different bouncing off the ceiling made the light very very large. But the overall exposure is right where it needs to be in there wasn't a lot of guesswork. I basically turned up the flash until I was getting the aperture that I wanted. And then I put those settings into the camera, and I took the exposure and there really wasn't a whole lot of guesswork there. If I wanted to use the light like it is but I wanted to get a larger depth of field, I'd have to use a smaller aperture. So in this case, what I would do is take the flash and turn it up all the way to full output. And then take another meter reading. And now I'm getting F5.6. So if I put that into the camera and take a shot, it should look fantastic. So with a handheld light meter you can see that it's quick and easy to get your settings dialed in on your camera and get your flash power set up so you can get proper exposures right away. This meter can also measure ambient light from constant lighting sources like the sun, fluorescent LED or incandescent. Now you might be thinking wouldn't it be easier just to use a constant lighting source. Well, maybe. But there are some benefits to using flash to light your products. And you're going to learn why coming up in the next lesson.

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