What Are fstops

The f stop goes by many names, including aperture, lens opening, f-number, relative aperture, and aperture stop. While each of these names don't always mean precisely the same thing, they all refer to the relative diameter of the opening, or entrance pupil that admits light to the lens. The larger the opening, the more light the lens can potentially transmit to the sensor a smaller f stop limits the amount of light that can flow through the lens. The size of the opening is variable, and...

Neutral Density Filters

Neutral density filters are one of those high-concept tools with a function that's easy to grasp they add nothing to the image except density (by preventing some of the light from reaching the sensor), and they are neutral (so the colors remain the same). A straight gray ND (neutral density) filter increases the amount of exposure required, so that you'll need to use a larger aperture, slower shutter speed, or higher ISO setting to achieve correct exposure with the filter in place. You can even...

Lens Crop Factors

While 35mm film cameras use a frame that measures 24mm x 36mm about 1.0 x 1.5 inches , the sensor in most digital SLRs is smaller than that, producing a crop factor when the field of view of the average dSLR is compared with that of a 35mm film SLR or a professional-level digital SLR that uses a full frame sensor. Because larger sensors are much more costly to produce and require bulkier camera designs, most digital SLRs have a sensor that's smaller than full frame, as you can see in Figure...

How a Lens Works

At its very simplest, a lens element is a mostly transparent element made of glass, plastic, or some other material, with one or two curved surfaces that bend refract the direction of light as it passes through. A curve that bulges outward convex causes the light to converge towards a single point of focus. A curve that bulges inward concave causes the light to diverge, instead. One of the surfaces of the lens element can be flat planar and not curved. Figure 1.1 shows a simple lens element...

Contents

1 A World of How a Lens How a Lens Is What Is Focal What Are How the Aperture Affects Your Overall Zoom or Fixed Focal Lens Crop 2 Lens Controls and Manual Zoom Image Stabilization Tripod Filter Lenses without Filter Other Filters and Lens Attaching Filters and Accessories to Your Other Attachment Using Cokin and Similar Filter Cooking with Polarizing Danger, Will Robinson Color Correction and Adjustment Neutral Density Split Density and Graduated Infrared Special Effects Protective Filters Or...