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Depth of Field Pop Quiz

And so this is where we get into our first quiz where you need to really be accessing all the information that we've talked about before because we're talking about lenses we're talking about the apertures, the depth of field to see what is going on here. So, here is the situation. You are focused three meters away, that's ten feet for you Americans all right? Three meters away, what will give you more depth of field. And so what we're gonna do is we're gonna do an audience participation poll here and so you're choice is a 24 @ f/16, or a 28 @ f/11. I'll give you a moment just to think about it. More depth of field. Okay, those of you who think it's the 24 @ f/ raise your hand. Those of you who think it's the 28 f/11 raise your hand. All right Steve, the correct answer is the 24 @ f/16. First off, the 24 gives you more depth of field than the 28 so that leads you to more depth of field there. F/16 gives you more depth of field than f/ so it's got two things pushing it to have more dept...

h of field. And the actual depth of field will be listed over here on the right-hand side for anyone who wants to really dig into it. So let's try this again. You're focused three meters away what will give you more depth of field? A 50 mm lens on a 1.5 crop frame body, a 50mm lens, they're both @ f/8 on a full frame body, or, as a third option-- (audience member laughing) the same depth of field on both? It's that whole crop frame body thing. A little monkey wrench right under the feet there. Okay, who thinks it's more depth of field with the 50 f/8 on the crop frame body? Okay, who thinks it's the same depth of field on both? Who thinks it's more depth of field on a full frame body? Lots of hands there. The correct answer is, same depth of field on both. 50 mm lens, it's gonna be the same. F/8 it's the same, it does not make any difference that it's on a crop frame body. It's the same lens set at the same aperture. The sensor behind the lens doesn't really make any difference at all. All right, you're still focused three meters away but this time which will give you shallower depth of field? So imagine you're at a situation where you're focusing on the subject and you want the background out of focus. And that subject is three meters away. Now can I throw another monkey wrench at you? The monkey wrench is that this 35mm lens sells for $2000. And this 50mm lens sells for about $100. All right, now just forget that information I told you right there. It's hard to put away, but when you know that, that sometimes influences your decisions. So we want the shallowest depth of field for our shot here. Okay, it you want that shallow depth of field who is gonna reach for that 35mm lens? Who's gonna go for the 50mm lens? So here it's the competition of what's gonna give a shallower depth of field, a longer telephoto lens or a wider opening aperture. You guys did very good on that. The 50mm 1.8 will give you the shallower depth of field. And so it's just that the 50 has more power compared to the 50 that little bit of change in the aperture right there. And it shows you, just because you spend a lot of money you can actually spend less money and get shallower depth of field but it's a different focal length so it is something that is different there. All right so we're gonna be playing a little bit of a game here and I'm gonna kind of go through the first one. This is kind of the practice quiz. And so what I'm gonna do is I'm gonna give you the aperture, so you know the aperture that we're gonna be shooting in. In this case it's 5.6. And does 5.6 give us a lot, or shallow depth of field? Well it's kind of in the middle of the range so that doesn't really tell us too much information. The next clue will be the focal length. Now the 50mm lens, is that shallow or great, well that's kind of in the middle again, so that's not giving us much information so that's not a great place to look at. The third piece of information that you're gonna get is where we're focused at. And if we are focused only one foot away, that's a big clue, because when you focus up close, it's gonna be very shallow depth of field. And so the question will be what does the background look like, is it in focus, slightly out of focus, or very out of focus? The way we're gonna work this quiz is you're just simply gonna hold up a hand like this, one, two, or a three. All right? And let's just practice. Go ahead this is practice, no points being kept score on this one. What do you think the background is gonna look like, is it gonna be in focus, slightly out of focus, and very out of focus. And what I mean by in focus, is if somebody was back there holding a newspaper, could you read headlines on the newspaper? Raise your hands, one two or three. Okay, and in this case, the background is very out of focus. So we're focused with a 50mm lens up very close and you can see back here it is very out of focus. And lets go ahead and put that back there. So that is very out of focus. This is how the quiz works. You guys ready for these now? So the first official one is f/22, just go one at a time, does f/22 give you lots or shallow depth of field? All right now, 16mm lens, does that give you a lot or shallow depth of field? And then add in, focused at three feet away, and we want to know if that background is sharp, maybe it's just a little out of focus, or very out of focus. So let's raise our hands in answer, what do we think it is? I see some ones and I see some twos For the most part. Let's take a look at the photo. So that background is in focus. That wide angle, that f/22 kept us in very sharp focus in the background in that one. So 16 and 22 really combine, we can focus almost anywhere and get sharp focus. All right, next up. We're going to f/ with a 100mm lens, how much depth of field do we get at f/16? What about 100mm lens? What about one foot away? All right, and so, in some ways what you can do on this is you can say, one pulls me this direction, one pulls me that direction and the other pulls me in that direction, so its probably going this direction. They're not perfectly even because sometimes one is more powerful than the other because if one's just a little over here and the other one's way over on the other extreme, you know it's gonna kind of be pulled and so it's almost a weight issue, but it's not exact. All right, let's ah, let me think about this one myself I forget what the next photo is, so I'm gonna say, (mumbles under breath) okay, everybody raise your fingers, let's see your answers. So I'm seeing lots of twos, a one and a three and the correct is very shallow depth of field. And so this is a macro shot with 100mm lens, focused just about a foot away, f/16 even though we're setting f/16, in macro photography we just don't get much depth of field. Very out of focus background. All right, down at f/11, and this is with, we just had a 100mm lens, so it's the same lens, near to the same aperture but now we're focused near infinity. Okay, so think about that for a moment. Same lens, similar aperture, but focused very far away. Okay, raise your answers, let's see what we have. One, two or three, don't look at me, I'm not raising my fingers, here. So we're seeing lots of ones and twos here, so it's either in focus, just slightly out of focus, and here's the actual photo, that background looks like it is in focus in this picture and so, in this case, the reason that background is mostly in focus in my opinion, is because we are mostly focused on infinity. We're focused out here somewhere and that background is in focus especially at f/11. Okay, down at f/8. F/8 getting more toward the middle of the range there but we've got a 135 lens focused pretty much right at infinity. This has some similarities to the last photograph it seems like. Okay, let's raise our answers, one, two or three. Think what this is, raise 'em up high so I can see 'em and everyone in back in the world can see 'em. Ones and twos here, it's either in focus or slightly out of focus. We're focusing on infinity, the background is almost infinity so it is pretty much in focus in this case. So the ones were the correct answer there. All right, let's go down to f/ with a 16mm lens. So f/4 pulls us in one direction and 16 pulls us in another but we're focused out beyond 30 feet. Fairly far out there so which way is the focus being pulled. So is the background gonna be in, slightly out...? Let's raise our hands up, what are the answers? I see ones, twos, three in there. So in this case, the background is in focus. With a 16mm lens, focused at beyond 30 feet, way out here in the distance, the background is gonna be in focus. So that 16 has a lot of power and the fact that we're focusing way out there, it's pulling us to keeping everything in focus. Let's go down to 2.8 with a 300mm lens. Okay so think about what a 2.8 does. We haven't dealt with a 300mm lens in the quiz here so what is that gonna do? And we're focused right about 10 feet away. All right let's raise our answers up. So I got some threes, twos, threes and twos. And the correct answer here is very out of focus. And so when we use a 300mm lens, and we're focused only ten feet away we are gonna get very shallow depth of field especially at f/2.8. All right down at 2.0 with an 85mm lens, now remember we said that portrait photography was pretty good with an 85mm lens. And f/2 might be a place that you would shoot a portrait shot. But we're looking at 30 feet away. What is that background gonna look like. All right let's raise our answers up raise our hands up. I got some twos and threes, mostly twos being answered here and that background is slightly out of focus. So I think most of you got that one right so there's your portrait shot shooting at that shallow depth of field with an 85mm lens and our background is, slightly out of focus, nice job on that one. That was one of the trickier ones, I thought. Okay, so our depth of field is controlled by those three factors and you have to weigh what does what. Now if I had to express an opinion as which one has the most power, I think it's the shooting distance because when you get close up, it is just always really really shallow depth of field. I think the next most powerful is the focal length and I think the aperture has the least impact on the depth of field that we have but it's the one we can control just by making a setting change in our camera. But they all kind of work together and so you have to know all of those to figure out exactly what depth of field you're going to get.