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Focusing
the View Camera  I
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and Adorama. INTRODUCTION All you're doing is moving the film around to frame and focus the 3D image formed by the lens. Just look at the ground glass while you move it around. There are no secrets. Reading books can confuse you if you're not already fluent in optics. Go play with a camera and pay attention to what happens as you move things. It's easy once you try it a few times. Just focus with the knob and move the ground glass around till it all looks good. Some movements interact, so keep moving the focus knob as you tilt the back. BACKGROUND The image formed by a lens is 3-D just like your subject. Closer objects focus at points closer to you. Imagine a field of flowers. The close flowers at the bottom are closest to you. The photo will require you tilting the film or ground glass a little closer to you at the bottom of the photo. The image on the ground glass is reversed, so the bottom of the photo is now on the top if the inverted image as seen on the ground glass. Simply tilt the top of the ground glass (or lens) towards you to bring the top of the ground-glass image (the bottom of the photo) into perfect focus. This is easier in person since the image is on the glass for you to see. Once you adjust the top of the ground glass, chances are that the bottom shifted a bit, depending on the design of your camera. On many camera you may want to move the focus adjustment a bit as you move the top to keep the bottom in focus, too. TRICK: The Scheimpflug Observation Scheimpflug observed that when you get this all adjusted, that the planes of the film, the lensboard and the plane of best focus all intersect along the same line! Normal cameras always have the film parallel to the lens. Therefore the subject in best focus is always a plane parallel to the film and their intersection is infinitely far away (parallel planes never intersect). This plane of best focus moves forward and back as you focus in and out. Every photographer is familiar with this effect. Now imagine tilting the top of the lens a little bit forward, or the film plane (ground glass) a little bit backwards. TIlt either one just enough so that their imaginary planes intersect at your feet. Now the plane of best focus also runs through your feet! This means that you now have perfect focus from infinity at the top of the frame to your feet at the bottom. You only need depth of field to keep things outside that plane in focus, like if a plant rises above this plane. This is how view and larger format cameras keep everything so sharp. There are some odd tilt and shift lenses available for smaller cameras to do the same thing. FURTHER READING The Adams and Simmons books are the best. I'd skip the Stroebl book as too complex unless your prefer to read about it instead of do it.
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