Camera Movements : Focusing
So focusing is always gonna happen on the ground glass, so there's nothing you can do to focus outside looking here. If it is not sharp here, it is not gonna be sharp on the film plane. If it is the, I mean the tiniest bit out of focus, the film's gonna be out of focus. So you really wanna make sure that we've got everything sharp and in focus there. It is always easier to focus on two-dimensional objects than three-dimensional objects. One plane in space, you focus on that one plane, you adjust the f-stop a tiny bit in case there's a little bit of thing on the surface, and everything's great, but when things get into three dimensions, we have to start to account for things forward, things back, and how do we pull those three-dimensional objects into focus. The other piece that happens with that is things will look in focus on a large format camera, but they're not gonna be in critical focus, so at some point, you're gonna need to use a loop, or like I said, I like to use my little fan...
cy, super fancy glasses, and as you get behind the ground glass, if you're using a loop, you're gonna be right up about here, with these kind of glasses, you end up right about back here, and you're gonna check every square inch of that film to determine what's in focus and what's out of focus. Because you can make some decisions about how much you wanted to focus. You could adjust the movements of the camera so just the tiniest little sliver is in focus. The equivalent effect of about a 1.4 lens, or a 1.0 lens. (mumbles) Tiny little sliver in focus, or I can make everything to infinity in focus. We look back in history of photography, some of the f/64 group, Cunningham, and Weston, and Adams, they were using a large format camera and using the advantage of the large format camera to get everything in focus. They were taking from the very, very front edge of the image, back to infinity in focus because of that power of that camera, but you had to check that on the ground glass. If one of the other pieces to really watch for when you're focusing is the corners, and we're gonna talk about vignetting a bunch as we start to move through a couple of things here in a second, but as you make the movements, the camera lens has got that circle of illumination. As it starts to get elongated or warped, as it hits the ground glass, it may not make the full corner over here. It may clip itself, so we have to make sure that we're getting the full illumination back here so we don't get vignetting, and we have to make sure we stay in that circle of good definition, so we have a really sharp image, and that we actually have the sharpness we want, so you're gonna be constantly checking your corners, constantly checking things in the middle, and you're gonna check multiple times. You can never check your focus too much. If you're gonna be, if you were OCD about anything, it's gonna be checking your focus because if I make this tweak to the camera, and I make just a slight little movement like that, I have affected the focus. If I make a little movement back the other direction, I've affected the focus, so any of those changes, I'm gonna need to come back and rethink about focus over and over again. So, once I get it focused, though, the most important part of that is that I gotta lock everything down, because at that point, if I lock everything down, nothing can then move to change the focus of the camera. I have, more times than not, I've put this little bit of tilt in like that, everything's been great, and then I'm doing something, and I do that, and I accidentally bump it. Now I gotta come all the way back, get under the dark cloth again, get all the work done, to get that movement back, so once you get everything done, you're gonna want to make sure everything gets locked back down, and everything gets locked, 'cause any of these get bumped and moved, focus is gonna change, so once focus is set, you wanna lock that down. Now one of the cool things I mentioned about focusing is I can play that infinite focus game, where I can take something from the foreground, out to infinity in focus, or I could reverse that effect. And that principle's called the Scheimpflug Principle. So there is actually two people who kind of figured this engineering behind this and how the optics and the light actually works. There's a lot of very nerd science behind it. For us, what we need to know is a tilt of the lens plane, and how it affects the focal plane, dictates how the image actually works, so this is a cool piece, so if we look at this image over here, I have my film plane, which is along the back of the camera, and I have the lens plane. When the camera's straight up and down like this, my lens plane and my film plane are parallel to one another. Now I wanna photograph the tree and the Langley Bunny. The Langley Bunny's a real bunny. I live in the town of Langley, Washington, up on Whidbey Island. People always wanna know about the bunny thing I have in my presentations. Many years ago at Langley, on Easter, they thought it'd be fun to give away baby bunnies, baby ducks, and baby chickens. For kids to come in, and pick up, and then take home as pets, and after about a week, I think the parents decided, no, no, no, we are not keeping a bunny rabbit, and they took them back to the fairgrounds and released them, so Langley now has hundreds of domesticated wild bunnies. When you drive to the town, there's bunnies everywhere, and I have a bunny project, 'cause I like to photograph them. So I wanna get this bunny in photograph, in the photograph, in focus, but the tree that he lives under, I also wanna get in focus. With a standard camera, here is the plane of sharp focus, so when we focus a camera, there's one plane of focus. Depth of field creates an area of acceptable focus, and that's the point of resolution where our eye doesn't discern that things have fallen out of focus or they become fuzzy. That has to do with the circle of confusion and a bunch of nerd stuff we're not gonna talk about. What happens is, though, is that as I increase my f-stops, I'm basically increasing my depth of field, but because my lens plane and my focal plane are parallel, I'm only able to work out a certain distance to keep everything in focus, so I maybe can get to 12 feet, and then got to infinity and get the tree, but I can't get my bunny, and if I move over and focus on the bunny, I'm only gonna get the first half of the tree, but I want the whole tree, and the bunny in focus. This is where the Scheimpflug Principle comes into play. What I'm able to do with the Scheimpflug Principle is I can tilt my area of sharp focus. I'm able to take now the focus plane, because I've tilted the lens forward a little bit. I've now changed the plane at which focus happens, so that it's working on a diagonal. Now, out in space, the film plane, the lens plane, and the plane of sharp focus are coming together outside the front which has caused, basically, this diagonal to happen. Now, as I move depth of field, it moves like a cone does, so it moves out like this. That then for allows me to grab the bunny and the tree, and bring them all under sharp, critical focus. This is really cool, and of all the things that a large format camera does, if you're a landscape photographer, a tilt shift lens will give you this a little bit, but this is really the hallmark of getting to use the power of a large format camera, and when people look back at Edward Weston, and they look at Ansel Adams, and they look at Cunningham, and all those people who had those amazing large format pieces. If you look at Jack Dykinga's color work out of Arizona, anybody who's worked large format, these things are so tack sharp in focus, and yet these objects in the foreground are huge, so you know they had to be close, because there's no telephoto compression. It's wide angle, everything is super sharp in focus. It's because of our ability to do this with the large format camera, that's allowing us to actually create depth. Now I can also reverse that. I could tilt back, and make the actual film plane work the other way, and actually start to kick things out of focus, so I could kick it back this way, and reverse the effect of the Scheimpflug Principle, and take the diagonal this way. So I've got options of actually controlling and manipulating this. This is a huge, powerful tool in focusing. I mentioned you wanna get everything set and then lock in for focus. If you are gonna do that lens tilt, to apply this, you would apply this before you actually lock everything down on the camera. It becomes a secondary piece. One of the other things that's really important when you're dealing with focusing, is behind the, on the ground glass, behind here, I've actually got all the image and everything's working, and I'm getting to look through the camera, everything looks great, but that lens in here, if you see it start to shift this way, get my shifts turned back on, okay. That lens now is technically pointed back this way. So if we look back here, across the back, that lens is gonna come across this way. Okay, I might not actually have enough lens coverage, because of how cattywamped I've made this, to fully cover the edges here. So, I need to make sure that I've stopped down enough so that I don't accidentally vignette this corner by all of my movement, 'cause what's happening there is the bellows and the lens phalanges are causing the image not to fully show up. So a lot of cameras, there's a way to check that because they cut the corners of the ground glass. This particular camera, they don't do that, but on this camera, its edges are cut. I'll show you in a second, but you can see on this camera, in the ground glass, that it's not completely to the edge. There's a tiny little notch cut out there. That notch is also on this camera, but it's really small, and you can't see it very well. The notch is really important for the functioning of the large format camera because as that bellows moves in and out, there's a change in the air pressure, and if that notch wasn't there, the air wouldn't be able to leave the bellows, and it would actually cause the glass to crack. So that's allowing the air to move in and out of the bellows, but the other thing that does in a lot of cameras, it allows us, this camera has it as well. There's the corner you can see and check through. What that allows us to do is to look for something called the cat eye. We call it a cat eye 'cause it kinda looks like the pupil of a cat's eye. So, on this next slide, I have the little piece. This is the actual camera over here, the 8x10 camera. Where the green circle is is the cutout. Now, I am what you call a master animator. I can make things look so amazing, I'm like the Michael Bay of Keynote. I only say that this will be the worst animation you've ever seen in your life to show this effect. I just wanted to make sure you felt good about yourself. So, as we zoom in, we're poof, now inside the bellows. (sniggers) You will see that effect up where the lens is. That's called the cat eye. Now, because it is this shape, that indicates that I'm gonna get some vignetting. So, what that means is vignetting on the film is gonna mean the exposure that hits the edge of the film is not gonna be as strong as the other parts of the film. So I'm gonna have to, I would then basically have, either it would be significantly underexposed, and I would have to either compensate for that in the printing, or it might end up being so underexposed that there's nothing there and I'd have to actually crop it out of the frame. Either way, it's a problem. When I'm normally focusing, I'm gonna have the lens open as wide as possible. We're gonna talk about the actual lens here in a second, but in my process, the lens is gonna be set as wide as possible, so that I can have as much light back here to focus with as possible. When I then am ready to do my critical focusing, I'm gonna start to move my f-stops, so I'm gonna decide what f-stop do I need to get to the focus that I want. So I'll start to move. On this lens, it's this, let me tilt this down just a little bit so it's easier to see. On this lens, the f-stop's controlled by this little light piece here. I start to move that, and at some point, I'm looking at my focus, and everything comes in as nice, tack sharp. Everything looks great. I'm really happy. At that point, I start to look for this cat eye, so I start to check my corners, because if I see this cat eye, even if I'm at the f-stop I want, I'm gonna vignette. So the way you get around that is you continually lower your f-stop. So if I'm set for f/22, I might go to f/32, or f/45, and what I'm looking for is when I can see the actual full opening, and it won't always be round, because depending on the blades that are in your lens, it'll look like an octagon or a hexagon, you're looking where you can see that completed circle or near circle. That tells you that the light coming through to actually hit the film plane, you'll get the full circle of coverage. And that's really critical if you're actually gonna make sure you get the image you want. That thing has bit me more times than I can tell you. We look back in the section one, we had the image of the tree going across. I love that photograph. I actually have to crop the top about 3/4 of an inch off that image because I had vignetted the image so much and I forgot to check my corners, and I didn't see the cat eye, and I ended up having the image, and I've actually had to crop it out of there. So, if you just for some reason don't do that, it will eventually bite you. Now you may shoot a thousand photographs and never see it because you don't make aggressive enough movements, but at some point, that will come up.