Features of Large-Format Cameras (2)

By TAMADA ISAMU

What is a Large-Format Camera?

There are two basic large-format camera types: the studio type which is designed for studio use and the field camera which is mainly for outdoor use. There are major differences between these two camera types.

Studio-Type Cameras

One feature of a studio-type large-format camera is its modular flexibility. The camera's various components can be detached and interchanged with other components to suit various picture-taking conditions. The bellows and monorail can be changed to allow the use of wide-angle lenses having a short flange back (back focal distance) and long focal length lenses having a long flange back, A 4x5-inch format camera can also be configured to accommodate 5x7-inch and 8xlO-inch sheet films.Many system accessories are also available. Major large-format camera makers include Toyo, Horseman, Sinar, and Linhof.

Basic Structure

The camera basically consists of a front standard to which the lens is mounted, a rear standard to which the ground glass back is attached, a bellows which joins the front and rear standards, and a monorail (optical bench) on which the front and rear standards travel on. Both the front and rear standards are capable of camera movements. The monorail has a tripod mount for mounting on a tripod or camera stand.

Monorail

Serving as the camera's base, this is an essential component for studiotype cameras. Many monorails are tubular and made of a light metal, while others are non-tubular. A single tubular monorail is 150 to 1000mm long. Most monorails can be extended by using connecting joints. Non-tubular and pole-type monorails do not have connecting joints. However, some have telescopic extensions which can be pulled out. For normaf studio photography, if the monorail is too long, it hinders camera operation. The monorail should more or less be 100mm longer than the focal length of lens used. For example, if the lens focal length is 65 to 90mm, use a 150 to 200mm monorail. If ft is 210 to 240mm, use a 300mm monorail. Or use a monorail which can be adjusted to the suitable length. Also, choose a sturdy monorail which does not bend or lurch even while it is extended or when a long focal length lens is used.

Front and Rear Standards

In the case of a 4x5-inch format camera, the front and rear standards are the same size and they have same-shape, metaltic frames. The attachments can fit on both the front and back of the standard. The standard's size determines the bellows size, Iens board size, and various functions. Normally, the lens board is mounted on the front of the front standard and the ground glass back is mounted on the back of the rear standard. The bellows is attached to the back of the front standard and to the front of the rear standard. The two standards are thereby connected to each other. Also, many studio-type cameras can be converted into a 5x7-inch or 8xlO-inch format camera just by changing the beilows and rear standard.

Bellows

Made of genuine or artificial leather with gathers, the light-tight bellows can be extended or shortened. A frame on both ends of the bellows enables secure attachment to the front or rear standard. Regarding bellows types, there is the conventional accordion bellows whose size is the same throughout its length. Then there is the bag bellows whose width is larger in the middle. The bag bellows can contract more than the conventional bellows since it does not have any gathers accumulating and getting in the way. The bag bellows allows camera movements even with wide-angle fenses whose back focal distance is short. Photography with a long focal length lens, closeups, and macro photography require a bellows longer than a conventional one. Bellows which converts the camera for the 5x7-inch or 8xlO-inch film format is narrow at the front and wider at the back, The front of the bellows accommodates the 4x5-inch format while the back fits the 5x7inch or 8xlO-inch format at the rear standard.

Camera Movements

The front and rear standards can be moved freely or fixed in place on the monorail. Fine movement controls are afso provided. The standards can also be shifted up, down, Ieft, and right, swung left or right, and tilted forward or back. These are called camera movements. The standards on the monorail can be moved by simply loosening the standard and moving it physically. Some standards have a gear action which requires a knob to be turned to move the standard on the monorail. The former type usually uses a tubular monorail. It allows the standard to be moved over a long monorail distance quickly and easily. The latter type makes the structure simpfer since it integrates fine movement control. However, the standard cannot be moved quickly over a long distance on the monorail. Some standards are shifted, swung, or tifted up, down, feft, and right by loosening the locking knob and pushing the standard with one's fingers. The locking knob is then retightened. Other standards are shifted, swung, or tilted by turning the appropriate knob. The former type has a relativefy simple structure, but precision movements are difficult compared to the latter type. The latter type has a complicated structure, butmovement scales allow precision movements.

Yaw-Free Mechanism

When the monorail is horizontal, swing movements can be made with the standard's rotation axis staying vertical. However, tilting the monorail wil[ also tilt the swing movement's rotation axis. When the standard is swung in this condition, it will incline to the side. Camera yaw thereby occurs, and the horizontal axis of the ground glass image becomes slanted. This yaw can be corrected by tilting the entire camera to the opposite side. However, each time the tilt or swing is changed, the degree of the correction must also be changed. Therefore repeated corrections may be necessary. To prevent such hassles, a yaw-free mechanism has been developed to maintain the vertical orientation of the rotation axis even when the monorail is tilted. More studio-type cameras are being equipped with a yaw-free mechanism.

Focusing

A Iarge-format camera is focused by moving the front or rear standard forward or back to adjust the distance between the two standards. You can check whether the image is focused by looking at the ground glass with a loupe. Although either standard can be moved for focusing, in the studio it is standard practice to move the rear standard for focusing. Moving the front standard for focusing wilf alter the subject distance, resulting in a different magnification of the subject.

Horizontal and Vertical Framing

If the camera has a revolving back on the rear standard, the camera can take horizontal or vertical pictures while in the same position. If it has no revolving back, the back must be replaced with a different one to change the framing orientation.

Field Cameras

Unlike studio-type farge-format cameras, field cameras are collapsible for lightness and portability. Most of the camera's components cannot be detached and interchanged with other components. And only a few accessories are available for field cameras.

Basic Structure

The box-shaped camera's front cover serves as the flatbed and the back cover is the ground glass back. When the front cover is opened, the collapsed front standard can be drawn out, The front standard moves on two rails attached to the inside of the front cover. The bellows is a conventional type which cannot be detached. The front end of the bellows is made narrower to save space.

Camera Movements

Compared to the studio-type camera, the field camera is highly simplified and the type and degree of camera movements are more limited. However with enough practice, you can execute the necessary camera movements for most picturetaking situations. Since most field cameras provide no camera movement scafes, camera movements are only approximate, according to visuaf judgment.

Focusing

With a few exceptions, focusing is done by moving the front standard. Technically speaking, moving the lens will change the subject distance. However, this is not much of a problem since most subjects photographed are far away. When taking closeup photographs with a field camera whose rear standard cannot be moved for focusing, set the camera at the proper distance for the desired subject magnification beforehand, then move the camera forward or back to focus the subject.