In this video, I want to talk for a few minutes about getting a correct exposure. Now, let's back up just a second and make
sure we know what we're talking about when we're talking about an exposure. An exposure is basically taking a picture and the settings that you're using to take that picture. So, that it looks the way you want. And that's what a correct exposure is, a picture that you've taken that looks the way you want. So, it doesn't necessarily have to look the same as what your eyes are seeing for it to be correct to you. But in this case we are going to use that as an example. Based on what my eyes are seeing, I'm going to set an exposure of a scene and just kind of walk you through the options you have to change to create a correct exposure and things to watch out for as you do that. So, let's just real quick... I'm in Scene Intelligent Auto. I'm on the Green A. We're just gonna stay here for just a second. I'm gonna press the live view button and here is the scene we're looking at. We have some flowers and for those of you who have
watched my other videos, you know, right now, I'm sitting under this big skylight. It's an overcast day. So, I have nice diffused light coming in. This jar of flowers is at the edge of that skylight and beyond that it starts to get pretty shadowy. Fairly quickly, you can see there's a ruler and there's
something white back there. We're gonna be able to see those things in a moment but here's what the camera judges to be a correct exposure of this image and it's pretty close. But, you know the camera doesn't always decide what's best and in this case to talk about all of our options that we have to change, I want to switch to manual and so that's what I'm gonna do now. I'm gonna rotate the dial to M and you should follow along, feel free to follow along. I think this is gonna be a lot more worth your time if you have your camera in hand and it doesn't matter if you have a Canon T4i or a Nikon, the general settings that we are talking about are identical for all of these cameras. So, here I am in manual mode and very nicely across the top now, I have the three options that I want to talk about when you're setting an exposure. Your first is your shutter speed. That is the length of time that your shutter remains open when you take a picture. Right now, it is set on one five hundredth of a second because last time I was taking pictures, that's what I had it set on and it remembers that and it keeps that there, until you change it. Next, I have aperture. I'm just gonna press 'Q' and highlight that. Aperture is the opening, the size of the opening of the lens. It's expressed in a fraction, we're not gonna go in detail to talk about that right now. But I'll just say that the smaller the number, the larger your opening. Lenses generally go from somewhere
around depending on how much you pay. 1.2, 1.4 all the way up to 22 to 36 in that general range. The F1.4, F2, F2.8 those are very large openings, almost as wide as the lens glass itself. On the other end of the spectrum the 22, F-22, F-36 those are tiny, tiny openings. Just barely large enough for you, to insert a pin through. That's your range. F5.6 is you know kind of a medium opening, again expressed in fractions and finally your final option here is your ISO. The sensitivity of the sensor. Now, I know that's not great, it's not very explanatory since I'm saying two
words and trying to use both of those in the same definition but the larger the number, the more sensitive that sensor is; that little piece of electronic equipment in your camera to the light coming in and it's a doubling factor. So, at ISO, at ISO 200, it is twice as sensitive as it is at ISO 100. At 400, it's twice as sensitive as it is as 200. I'm gonna stop stuttering over my words there and let's just go back to our main screen. So, let's press Live view now and it's showing us... This is one of the reasons why I really think live view is a great learning tool, I've said that in other videos. That's showing us the exposure we would get with these current settings. The shutter speed across the bottom five hundredths of a second. Our aperture 5.0 and our ISO of 400. If we half press the shutter, you can see that the camera helpfully says, this is where I think your exposure is relative to a correct one. Correct one should be right there in the middle, what the camera thinks is a
correct one and again remember what the camera thinks is a correct one and what you want is a correct one are not always the same. Often, they're very similar when you're just trying to take regular pictures but they're not always the same and, I don't know if you notice, but it didn't move a little bit, based on the
amount of light coming in through the skylight whether or not it's brightening the scene or darkening the scene. So, let's start to adjust our values of these settings to get a more correct exposure. First thing I'm gonna do the shutter speed is already selected one 1/500th of a second, it's pretty fast. I can go a lot slower than that before I run into any kind of negative effects. Do you know what those negative
effects might be? Did anybody out there say motion blur? Now, that is correct, in this situation the camera is sitting still. It's taking a picture of very still life, nothing is moving. So, you could go to shutter speeds very, very slow. So, multiple seconds and there wouldn't necessarily be any negative impact on your image and that would still give you a correct exposure. Let's do that just for fun, let's go all the way down and take a picture. One second lock. I dialed, sets one. Now, my image of course, is really overexposed. I'm gonna go to 100, that makes the sensor as less sensitive as possible and
now, by holding down the AV button, I can dial the aperture way up and notice 22
is the maximum for this lens and the camera is now saying that I am overexposing slightly, from what it believes to be a correct image. But this is actually very close to the image that I want to create here and I'm gonna go ahead and press the shutter button. It's going to take a picture. It took one second to take that picture. Let's go and put that on the screen for a second and get rid of all of the info. But you can see, one second F-22, ISO100
and there's my image and everything is fine. We should be able to zoom in, on
those flowers and they are a little bit brighter than I would like. But, everything is crisp and the image is just fine. We should also notice that the plant in the background although dark, is in focus. We'll talk about that in just a second more. Now, that was the example of going that. But what if I was taking pictures, what if I was holding the camera or if I was taking pictures of people moving? Well, those are two different things. So, let's say first if I was holding the camera and taking a picture of this flower. The one thing that you want to watch out for, is shutter speed slow enough that you
won't be able to hold the camera steady during them. If I picked up this camera and held it for one second, the image would be very, very blurry. The general rule of thumb is that your shutter speed should be a bit higher than your focal length. Right now, I'm shooting with a 35 millimeter lens. My shutter speed should always be above 35. The one time that you can break that rule and you're holding
the camera is when you have a lens that has IS, then you can go a little bit slower. But now, let's say you're taking pictures of something that's moving, somebody that's moving. Your kid, your toddler, a dog running in the backyard. Now, you're talking about shutter speeds that you want to be up around 100, 125th
of a second, one hundred and twenty-fifth of a second. That's a pretty good, safe shutter speed for movement, unless we're talking about things that are moving very fast or you can go a little slower if things are moving a little bit slower. In this case, you can see that my image is now very, very dark. So, what I'm gonna do is I'm going to roll my aperture, increase my aperture, a good bit. I'll go to 28, pretty close and now I can increase my ISO sensitivity to 400 and those flowers in the foreground are a little bit brighter than I want. I'm gonna go back down to 200 for ISO and now you can see that my exposure is identical; virtually identical and you can see that little exposure meter at the bottom. Virtually identical to the exposure I shot, a minute ago that was a one-second
in F-22 but notice there are other differences now. Let me go ahead and take this picture and press Play Back. Here it is. So, exposure wise brightness, it is
very, very similar. However, that plant in the background now, is very soft and not in focus because I was shooting at such a smaller aperture. So, aperture increases and decreases the size of your lens
opening and that allows in various amounts of light depending on the size of the opening but it also impacts your depth of field, how in focus things are. So, how I approach each situation as I say well, what kind of aperture do I want
for this and I set it accordingly; then I figure out the shutter speed I need
and set that accordingly and then if I need to adjust my ISO, to get the shutter
speed where I want it to be, then I'll do that. So, that's usually my approach. Start with the aperture and an easy way to do this, is to shoot on AV mode. You set your aperture, where you want. The camera will set the shutter speed and you still have to set your ISO based on that. You could also go to auto ISO if you want. I'm not a big fan of auto ISO. It makes... this is again letting the
camera have a little bit more control and the more control you let the camera have, the more likely it is gonna be to make a bad decision. It's kind of a bummer. We do have these really expensive really nice cameras but they're just not as smart as us. After a little bit of learning and understanding, these different, how these different settings affect our image quality. So, this was just a really quick simple look at changing those values, talking a little bit about exposure. I'm gonna come back with more videos that talk in depth. I'd like to have a series of kind of recipes but really it all depends on what you
see and the factors of fast enough to avoid motion blur, fast enough to avoid
handshake. The aperture that you want for the scene, whether or not you want to
kind of separate somebody from the background or it's a Vista and you want
to get all of it in focus, then you're gonna be shooting it at really high numbers, which is really small opening and then ISO and the one thing you want to watch out for your ISO with your kind of entry-level DSLRs, is still
around ISO 1600 above that we start to get quite noisy. And so, if you can keep below that number and the lower, the better usually, then you're going to have
a better, a cleaner image. But if you need to go higher to keep that shutter speed
from getting blurry or getting long enough that your image is blurry, then
you're going to want to do that because a slightly noisy, non blurry photo is better than a blurry photo. That's not noisy unless you're going for artsy
blurry. So, I hope this was helpful. If you have any questions about it, leave a
comment down below or find me over on the Facebook page. I do appreciate you watching. As I said more videos of this sort coming soon and I do try to keep
them as short as possible but we're covering topics that are fairly weighty
and I want to give them the time that they deserve. Thanks for watching.
