Light Meter Basics
Alright, in this section we're gonna be talking about exposure, which means shutter speeds, apertures, ISOs, and a bunch of other things as well. And so there's a lot of things to talk about. This is, as I said, I think it's the crux of the class. So here's a list of the things that we're gonna be talking about in here and... Let's start off with a light meter basics. So all of your cameras have light meters on them. Now, what's really important to a photographer is they wanna know how much light is landing on their subject. If we know that, we will know exactly the right combination of exposure settings to get a perfect exposure. Back in the day, we used to use a handheld light meter. This Incident light meter. And they still sell these. You can still buy them. And you can go out and you basically go up to your subject, you press the little metering button on it, and it's gonna tell you right there in clear numbers what ISO, what shutter speed, and what aperture to get the absolute pe...
rfect exposure because it knows exactly how much light is reaching that subject. But walking up to your subject is not always so easy, especially if you're photographing a mountain, you know. You gotta walk a long ways to get there. It's fine if you're shooting a portrait, but it's not very convenient. And so what cameras have these days, and for many, many years is a Reflected light meter. And what it does is it measures the light bouncing off of our subject going to the camera. Now this is not as accurate because now we have two sources. We have our light source and then how much light is reflected by our subject. And our camera doesn't understand what the values and factors are of these. Now, the metering system in your camera is located probably pretty close to the focusing system for a lot of the SLRS. With the mirrorless, it's slightly different. It's taking it off the sensor, but there's a sub mirror behind the main mirror where it's reading this sort of light as you are actively looking through the camera. Mirrorless cameras are just doing it off the sensor. Now what they're doing is they're basing what they see as far as the amount of light coming in your camera. It's based off of the Kodak 18% gray card. At least Kodak used to sell an 18% gray card when Kodak was a thing. But it's based off of a middle tone gray 'cause it was figured that the world is kind of average about that brightness. And so, it's a good middle tone brightness, but clearly not everything is middle tone gray. If you are shooting something that's gray then it's perfect. This middle tone is gonna give you a perfect exposure in the background. The lights, the darks you're all gonna see, perfect. Where things get a little bit more difficult and challenging is when you're photographing something that's really dark. What's happens is less light gets to your camera. The light meter in your camera says, oh my gosh this thing is dark. And then your camera using that information goes, well we better change shutter speeds, apertures, ISOs or something so that we get a neutral gray medium brightness subject. And so it wants to correct for this sort of problem. And it wants to lighten the subject up, and it lightens everything else around it up. And so if you're photographing something that's really bright, too much light is getting back to the camera and it's thinking, oh my gosh too much light. Let's darken this because nothing is really this bright, and it wants to average it back down, and what's gonna happen is it's gonna darken it, and everything around it. Which is why sometimes you photograph pictures in the snow, the snow seems kind of dark and dingy, and it isn't as bright as it should be. The camera doesn't understand snow is different than grass or anything else. And so what you have to be aware of as a photographer are things that are darker than average, and lighter than average. The metering systems are pretty sophisticated these days, so they're really good, but you just have to be aware of these situations that kind of fallout of the standard norm of what the camera is expecting. Now the way that this light meter works in your camera, and the way that you get to interact with it is in your viewfinder on most cameras down along the bottom, there's gonna be what is known as a Graphic Light Meter, which means there's gonna be a little indicator that's gonna move off to the side like this if it is overexposed by one stop. It might look like this if it is underexposed by two stops, and then there's the third stop increments in there as well. And then if it's right in the middle, that's where you're getting your even exposure. Now there are some cameras that don't use a Graphic Light Meter, they use a Numeric Light Meter, and it's just simply a number. And it would tell you if you're one stop overexposed, you're plus one. And if you are underexposed by two, it's minus two. And so if you have to pay very close attention to which number that is 'cause there can be a lot of different numbers in there that mean different things. And if you're at proper exposure, it's just zero. I prefer the Graphic Light Meter, because it's nice and visual, and I think those things are easier to work with. So take a look and your camera and see how your camera is reading the light. Now the way it reads the light in your camera is with the metering mode that you have selected, and most cameras will have two or three, or sometimes more modes selected. The traditional mode that was on most cameras to begin with was a Center-weighted mode. This was kind of the simplest metering system that they could develop. It's a little bit more sensitive in the middle, and less sensitive out on the edges. And so usually is measuring about 60% of the information on the inside, and the other 40% on the stuff that's on the outside of the circle. So it's just weighted more towards the center of the frame. And this was good for subjects that was of average brightness, and in the middle of the frame. Photographers then wanted to be a little bit more precise about subjects that did not fill up the frame. So the next thing we had was Spot meters. And so this was really good for smaller subjects that might be in front of a dark or light background. We can now measure the light on that one particular subject. And so Spot meters have been very, very useful for photographs in the past. For portrait photography, they might measure the skin tones knowing that skin tones are usually around middle tone gray, sometimes one stop brighter. They could very precisely dial in what shutter speeds and apertures they wanted. Landscape photographers would take a Spot meter out, and they would take multiple readings of the highlight areas, the shadow areas, and they would figure out the range of brightness that they are recording in one particular shot, and then they would select their exposure wherever they need to in that setting. And this could be a very time consuming project doing this, and then figuring it out, dialing it in and so it's not, you know, for your real quick picture taking but it was very, very accurate. Nowadays, one of the most popular metering systems is what I would generally call a Multi-Segment metering system. And what it does is it breaks the scene up into a lot of different areas, essentially Spot meters, and then it compares and contrasts each of these little boxes and builds an algorithm for what the entire scene looks like. And what it can do is it can kind of disregard one errant, right spot, or dark spot, but it gets a better understanding of the total brightness and the brightness variance from one area to the rest of the scene. And this is the type of system that will be accurate or close to accurate a very, very high percentage of the time. So looking at the three different options here, Center-weighted is good if you have something in the middle that is of average brightness. The Spot meter can be very helpful for pin-point metering if you need to get a metering system reading off of a very small area. But for the most part, a lot of photographers like myself use the Multi-Segment metering system, which by the way, goes by a lot of different names. Canon calls it an Evaluative metering. Nikon calls it Matrix metering. I think Sony calls it Multi-Segment metering. Lot of names like that, and a lot of different symbols, but generally there's a lot of areas that it's doing that measurement. It's gonna be really good. And with the advent of digital cameras, and being able to see those images on the back of the camera. It's pretty easy to see if things are working or not. For those of you with mirrorless cameras, it's even better. You can just look at the screen, and you can see if it's too bright or too dark in many cases. And I think these kind of traditional light meter systems, may not be around forever. I think there are better ways of reading light than these, but they do a good job. And the Multi-Segment metering system is how I leave my camera most of the time, and that's because I shoot manual exposure, and I'm checking the back of the camera as we'll get into the next section. But it's gonna do a good job the predominant amount of time. Some people like to switch over to Spot once in awhile, and not too many people are using Center-weighted, but it's there for legacy reasons, and there's a few people who like that.