Large Format Lenses
Now, which lens to buy. So, there's a few types, there's a wide, normal, long, telephoto, and then a convertible. Those are your key categories in working with large format. One of the interesting of things that people ask about all the time is wide makes sense. That's a normal wide-angle lens, you're gonna have a little bit lower f-stop, you're gonna have a little wider coverage, they kinda get that but what's the difference between a long lens and a telephoto lens? A long lens and a telephoto in the 35 millimeter world are compressed into the same lens. So they're the longer focal lengths, they're your 200, your 300, your 400 millimeter lenses. They're the long lenses, they provide a telephoto. Now in a large format, that can be 600, 800, 1200, they're a little bit longer in the range because of the way the lenses work but the difference between a long and a telephoto is if you think about that bellows draw that was in here. If my camera only did a bellows draw, say to about this far...
, and that rear element, that piece that screws onto the back of the shutter, if that was this long, I wouldn't be able to focus very much, I wouldn't have a lot of options for focusing. So what the telephoto lens is, it's the same thing as a long lens except that rear element is shorter. So it allows me to have the benefit of having more of my camera movement at that same focal length. Now, if I have a camera that has a longer bellows draw, it's gonna be cheaper to buy a long lens than the telephoto lens. But it's gonna give me my additional movements. Now what that's gonna cost me is a little bit of light, it's gonna cost me a little bit of movement because of the way it's shorter, I'm not gonna have the full flexibility of the camera movement of the longer lens but I am gonna have the option of at least having that focal length for my camera. Wide-angle lens, like I said, same principle, a normal lens, about the same principle. Somewhere in that kind of 50 degree range, human eye range is about where we're gonna look at. We're gonna talk about angle of view in a second. A normal lens on a four by five camera, 90 millimeters. 50 millimeters, it's about 150 millimeters for that, so there's some really interesting things that are gonna happen in terms of what's a normal lens, it may seem like a telephoto lens if you're coming out of the 35 millimeter world but we're gonna talk about why that is. A convertible lens is a really kinda cool lens, what that has is there's multiple rear elements. There's two or three rear elements, so you have the same front element and the same shutter and you can attach a different rear element and get a wide-angle, a normal, a telephoto, or a super telephoto lens through all of those different elements. Okay, key considerations for buying a lens and key considerations to think about the lens. The first one everybody thinks about is focal length. Focal length is all about the angle of view. So this is one of the really interesting things about when we're thinking about how to work with a large format camera. The diagonal of the film is significantly larger than it is with 35 millimeter film. And that diagonal and the focal length determine the angle of view. So, if we're working with a image, I've got a 35 millimeter negative, I have 28 millimeters is the equivalent of a 90 millimeter lens at four by five and that's the equivalent of coverage of a 200 millimeter lens. So, if I am a large format, small format photographer, and I normally shoot 28 millimeter if I want the effect of 28 millimeter on my eight by 10, I need to shoot a 200 millimeter lens. So, if I'm going out shopping, I'm gonna shop for 200 millimeter, not 28, you're not gonna find a 28 millimeter lenses, in fact, for eight by 10. They don't make 'em. It's too much coverage, that lens would be about that big around probably, on the front of the camera. So you're not gonna have that as an option. And I kinda went down here at about 105 millimeter, that's kind of a nice focal length for portraiture. So you could see, it's 360, 720 on the sizes there. Most people for four by five, it's gonna be around is kinda the standard focal length. People really like 200 to for a portrait and on eight by 10, it's not quite 720. It's in the 500 range so if you're gonna do portrait photography, those are the kinda the lens sizes you would think about. Now, the next thing we're gonna talk about is the actual angle, the amount of coverage that a lens gives you. That's the other big consideration because if you buy a lens and here's a sheet of four by five film. And if you buy a lens that only has the amount of coverage provided by that blue circle, that's called the circle of illumination. That's how much light comes through the lens as the light enters the lens, it forms a cone. That cone goes back and hits the film plane. If that circle is only the size of the blue, I can't have any film movement, so all those cool things I bought for my camera to let me control perspective aren't gonna happen because I'm gonna vignette. But if I actually have a circle the size of that green, what it's gonna allow me to have is significant movement of the camera. So I can actually move my, all the different pieces of my camera, I can move and still have full coverage of the film. And that's one of the big things that when you're looking for a lens, people go to focal length first, but for me, it's area of coverage is the most important. Because the amount of movement I can have with the camera before it starts to fall off and vignette or go to pure black from the vignette is for me the critical aspect because I wanna be able to utilize all the different components of the camera as best as possible. The next thing after the circle of illumination is there's also, 'cause we wanna make it really complicated for you, there's something called the circle of good definition. So inside that cone of light is the light that hits and inside there is where the data of the light or the information of the light is actually acceptably sharp. So that's the circle of good definition. So in this case, if I have my, you can see how I start to fade out and I get a little bit fuzzy here as I make that transition, that is my circle of good definition is in where the green arrows stop. If I put a piece of four by five film up, you can, if I put a piece of film actually up, and not magic film, you can actually see that my film is now gonna be outside the circle of good definition. What that means is anything out here is gonna have a softness to it. So it's not gonna be completely sharp. Now, one of the things that most manufacturers have done, which is really great is when they talk about their camera and when they talk about their lens, they do that circle of good definition at f/22. So, when you read about a lens and when you're doing all your research and it says that the area of coverage and the circle of good definition is x for this lens, it's usually measured at f/ and that's gonna give you an apples to apples comparison. Because the circle of good definition and that available light as the smaller the f-stop gets, the more information you're gonna have. So f/45 is gonna give you a sharper image than f/16 would, f/32 would, so if the manufacturers were trying to really make it difficult for us, some would record I have f/64 as great coverage, where f/22 is great coverage, where f/45 is great coverage, and they would go find their sweet spot. But for the most part, everybody who's measuring the lenses is measuring them at f/ or sorry, f/ and that's really a great spot. Other considerations for the actual selection of the lens, shutter speed. So one of the things that working with a large format camera is this lens, it's fastest shutter speed is 1/25th of a second. It's fastest. So, if you're used to shooting a thousand, two thousandth of a second, that's not the lens for you. This one I got, this is a really fast lens. This one goes up to 500. 500th of a second. That's about the fastest you're gonna find, you might find a thousandth of a second but large format lenses, because you're stopping down and you're not gonna have as much available light, super fast speeds are not gonna happen. That being said, they're all leaf shutters. So inside here, this shutter is a leaf shutter, which what that means is though I can flash sync at any speed. So, rather than the film plane, which goes up and down, the leaf shutter moves in and out. And because of that, I'm able to flash sync at any speed. The other piece you'll find on a lens when you start to look around is most of them have what's called a B setting for bulb and a T setting for time. I would not buy a lens that did not have the T setting. The difference between bulb and T is they both fire and open the shutter. Bulb is when I push the plunger in, the shutter fires and as soon as I let go, the lens closes. The T setting says I push the shutter once and the lens opens and until I push it again, the lens won't close. So if you're gonna have exposures three, five, 10 seconds, minutes, hours long, however long they're gonna be, the T is gonna have you not have the accidental release of the shutter and close the shutter too soon. So, I love the T setting for that. So that's another kinda key consideration. The other one is, I don't know if you've noticed, but those are kinda different sizes lenses. And if you look at the shutters on the side, you could see the shutters are way different in size. So, shutters come and there's basically a number of different sizes and a number of different brands. A Compur and a Copal shutter are the two most common and they come in sizes from triple zero up to three. That is a size three shutter. This is a size one shutter. A size triple zero is extremely small. That shutter is gonna determine a number of different things but that's a weight consideration. So that's one of the other big considerations is what is the actual weight of it and that's oftentimes dictated by the shutter. Another key component, like I said mentioned, was that flange distance on the telephoto versa long lens. This spot from here to the film plane is our flange distance. So as I'm looking at lenses, I'm gonna pay attention to that flange distance to see how much coverage do I have back there in the camera to make those decisions.