This is a continuous post of our previous posts. We started these articles for sharing the photography basics tips for beginners. If you want to share your experiences or tips to our users, please send an email to firstname.lastname@example.org
This post is Part 6 of Photography Questions and Answers for Beginners. You can check our previous posts here:
- Photography Basics – Questions and Answers for Beginners – Part 1
- Photography Basics – Questions and Answers for Beginners – Part 2
- Photography Basics – Questions and Answers for Beginners – Part 3
- Photography Basics – Questions and Answers for Beginners – Part 4
- Photography Basics – Questions and Answers for Beginners – Part 5
What is Bellows?
Although bellows form the camera body of a view camera – rather than a metal or plastic box – the word usually refers to a dedicated piece of equipment for close-up and macro photography. Separating the lens and camera increases magnification;a dedicated set of bellows gives flexible, intermediate levels of magnification as opposed to the fixed reproduction ratios of extension rings or tubes. Some bellows retain communication between the lens and the modern electronic camera body (auto bellows) but many do not,which means stop-down metering must be used. Some bellows offer swing and tilt to change the plane of focus or shift to crop images (useful ifa slide copier attachment is fitted).
Broad and Short Lighting
Turning the head to one side makes one aspect of the face appear wider than the other, referred to as the broad and short, or narrow, sides of the face respectively. These are also the names given to the two types of three-quarter lighting: broad lighting and short lighting. With broad lighting the key light illuminates the side of the face turned toward the camera; with short lighting the main light is on the side of the face turned away from the camera. These two types of lighting are often used to change the look of the width of the sitter’s face. A thin face is made to look wider with broad lighting.
Chromatic aberration (CA) is a lens fault that occurs when the lens cannot focus different colors at the same spot. There are two types: longitudinal and lateral. The bending power of a lens refractive index [RI]) varies with the color (wavelength) of the light.Blues are brought to focus before longer wavelength reds behind the lens. To correct this longitudinal CA, lens pairs made of different glass with different RIs are used. These are called achromatic elements and,depending on the quality of the lens, correct for two colors (an achromatic lens) or three colours (an apochromatic lens). Lateral CA is seen as color fringes at the edges of an image, as shown in this magnified example from a zoom lens. It can be corrected to some extent by computer software;some cameras now offer in-camera CA correction with that manufacturer’s lenses.
These are sometimes called H&D curves after the scientists Hurter and Driffield) who first published them. A characteristic curve is a graph of the image density produced in a photosensitive material plotted against the logarithmic value of the exposure (which gives them their other name of D/log E curves). The slope and shape of the graph tells photographers about the contrast of the material, its tonal qualities and its handling of highlights and shadows. The slope of the curve is given the Greek letter gamma. A steep central portion means high contrast; a gentle slope means low contrast.
Rather than silver, the cyanotype relies on iron chemistry for its distinctive Cyan/Blue image. Discovered by Sir John Herschel in 1842, it is still popularly known as a ‘sun print’or ‘blueprint’. Being easily developed in water after prolonged exposure to UV light, the sun print is many people’s earliest meeting with photosensitive materials in school. Cyanotypes are usually associated with photo grams but they can be used with conventional negatives to produce full-toned images. The Victorian photographer Anna Atkins first used the process photographically in a series ofcyanotype books documenting ferns and leaves. It is perhaps one of the easiest alternative processes to try but also one of the most difficult to perfect.
Circle of Confusion
No lens can resolve an image point as a point; it produces a tiny disc of light that from a distance, to human vision, looks just like a point. This tiny disc is called the least circle of confusion. Images are created from a multitude of these tiny overlapping circles. Circles of confusion are produced when a lens is not in perfect focus and they get bigger the further away they are from correct focus. Another name is blur circle. Reducing the lens aperture makes the circles of confusion smaller, thereby increasing the apparent depth of field in the image.
This article was inspiration from book of The Visual Dictionary of Photography. You can purchase this book from Amazon to explore more.