Photography Tutorial, Large Format Camera Movements 1

This is the Sinar P3. It is the absolute bollocks of a Camera. It weighs over 13 pounds with lens and a Digital recording back that produces 33 Megapixel, 190 MB, 48 bit TIFF images.in a single shot. Not for the faint-hearted!

Cameras like these, which are still in production, from Sinar, Linhof, Horseman, Toyo and Ebony are classified as Technical Cameras. What sets them apart is not the image quality but the two things that your average DSLR, SLR cannot do - that is altering the perspective and the plane of focus.
Why we would want to do this, and how to achieve it, is what this tutorial is all about. Proceed if you dare!

All Cameras are fundamentaly a lens at the front that projects it's light to an image plane at the back. Whether the image plane consists of a sheet of film or a CCD is irrelevant here. In between these two objects can be a myriad of high tech gadgets such as instant return mirrors, exposure calculating optics, anti-dust shakers and so on. On a technical Camera like this one you'll find a set of black leather bellows. That's right.
Archaic as it may seem nothing has been invented to replace the humble bellows first used on Cameras about a thousand years ago (circa 1835 actually). Why? Because it allows the lens to move independently of the image plane and vice versa while still retaining a light tight environment within.

In a small Camera, SLR or DSLR, Medium Format even, the configuration is set up like this diagram where both planes are fixed and the horizontal lens axis coincides with the horizontal image plane axis. This view is identical from the side or from the top. Focussing on any object that is in view of the lens is done by moving either of these planes closer to, or further away, from each other. The fact that the vertical axes of both planes are parallel means that the plane of sharp focus on the object must be parallel to these also. The Depth of Field around the plane of sharp focus is determined by aperture so a smaller lens f stop will increase depth of field. We all know this.

This is a Steel Embossing Roller used to imprint rubber matting on a huge machine that produces rolls of rubber matting all day long. The texture on the roller's surface does the work.
This roller is 13 feet or about 4 meters in length and 2 feet or 80 cm. in diameter, sat on tressles on the factory floor, it was a tricky shot as the Depth of Field was inadequate.

A more interesting shot perhaps is this rather succulent looking Pizza. From the Camera's point of view both these shots have identical problems. The Camera is looking down obliquely at a level object so the plane of sharp focus does not correspond with the subject plane.

Both shots where on a 5x4in. Sinar Camera like the one above. To cure the problem tilt the lens forward independently of the image plane. The bellows allows you to do this. The inclination of the plane of sharp focus changes dramatically, to a similar angle as the subject plane, and the Depth of Field now encompasses the whole roller (or Pizza) at only f22, not f32, so we've also opened up the aperture by a whole f stop which was rather fortunate because I didn't have enough light to shoot the roller at f32 anyway.

Though it sounds simple in principle some other fine movements may be needed to accomplish this feat. The lens may need to be 'dropped' a little to relocate the image on the image plane which, itself, may need to be 'back tilted' slightly owing to the acute angle of view. So, if you are still reading this, we should now familiarise ourselves with the range of Camera movements possible on technical Cameras, with terminology. The first set of diagrams look at the Camera from the side view. The Lens panel is known simply as the 'Front'. Image Plane as the 'Back'.

All these movements have a purpose and in the real world a combination of two or more of these movements are needed, not just to alter the plane of focus, but to correct Converging or Diverging Verticals, reduce or expand the Depth of Field and even, to a limited degree, alter the apparent shape of an object that would otherwise appear distorted. It's serious work for professional Studio, Architectural and Landscape Photographers who do this daily.

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