ENLARGER Model II
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Breaking Down the “Cosine Fourth Power Law”
Breaking Down The “Cosine Fourth Power Law” By Ronian Siew, inopticalsolutions.com Why are the corners of the field of view in the image captured by a camera lens usually darker than the center? For one thing, camera lenses by design often introduce “vignetting” into the image, which is the deliberate clipping of rays at the corners of the field of view in order to cut away excessive lens aberrations. But, it is also known that corner areas in an image can get dark even without vignetting, due in part to the so-called “cosine fourth power law.” 1 According to this “law,” when a lens projects the image of a uniform source onto a screen, in the absence of vignetting, the illumination flux density (i.e., the optical power per unit area) across the screen from the center to the edge varies according to the fourth power of the cosine of the angle between the optic axis and the oblique ray striking the screen. Actually, optical designers know this “law” does not apply generally to all lens conditions.2 – 10 Fundamental principles of optical radiative flux transfer in lens systems allow one to tune the illumination distribution across the image by varying lens design characteristics. In this article, we take a tour into the fascinating physics governing the illumination of images in lens systems. Relative Illumination In Lens Systems In lens design, one characterizes the illumination distribution across the screen where the image resides in terms of a quantity known as the lens’ relative illumination — the ratio of the irradiance (i.e., the power per unit area) at any off-axis position of the image to the irradiance at the center of the image. -
The Positive and Negative Effects of Photography on Wildlife
Gardner-Webb University Digital Commons @ Gardner-Webb University Undergraduate Honors Theses Honors Program 2020 The Positive and Negative Effects of Photography on Wildlife Joy Smith Follow this and additional works at: https://digitalcommons.gardner-webb.edu/undergrad-honors Part of the Photography Commons The Positive and Negative Effects of Photography on Wildlife An Honors Thesis Presented to The University Honors Program Gardner-Webb University 10 April 2020 by Joy Smith Accepted by the Honors Faculty _______________________________ ________________________________________ Dr. Robert Carey, Thesis Advisor Dr. Tom Jones, Associate Dean, Univ. Honors _______________________________ _______________________________________ Prof. Frank Newton, Honors Committee Dr. Christopher Nelson, Honors Committee _______________________________ _______________________________________ Dr. Bob Bass, Honors Committee Dr. Shea Stuart, Honors Committee I. Overview of Wildlife Photography The purpose of this thesis is to research the positive and negative effects photography has on animals. This includes how photographers have helped to raise awareness about endangered species, as well as how people have hurt animals by getting them too used to cameras and encroaching on their space to take photos. Photographers themselves have been a tremendous help towards the fight to protect animals. Many of them have made it their life's mission to capture photos of elusive animals who are on the verge of extinction. These people know how to properly interact with an animal; they leave them alone and stay as hidden as possible while photographing them so as to not cause the animals any distress. However, tourists, amateur photographers, and a small number of professional photographers can be extremely harmful to animals. When photographing animals, their habitats can become disturbed, they can become very frightened and put in harm's way, and can even hurt or kill photographers who make them feel threatened. -
The Slide Projector As a Computer-Operated Visual Display*
SESSION III CONTRIBUTED PAPERS: PROCESS CONTROL (INTRODUCTORY) Robert S. Mcl.ean. Ontario Institute for Studies in Education, Presider The slide projector as a computer-operated visual display* PAUL B. BUCKLEY and CLIFFORD B. GILLMAN have had experience with slides and can generate University of Wisconsin, Madison, Wisconsin 53706 appropriate stimuli easily. Furthermore, changing or .supplementing the stimulus set requires no new Advantages and method are presented for using the programming and no additional memory storage. slide projector in a computer-operated visual display Interfacing an inexpensive tachistoscope to the system. computer may also meet the E's requirements for a visual display. However, the projector is more flexible in The presentation of visual stimuli is a common that one can display many stimuli without E procedure in psychological research (Aaronson & intervention. so that intertrial interval is precisely Brauth, 1972). For example, visual stimuli have been controlled. Furthermore, two projectors with employed in our laboratory for experiments in superimposed images, paired in the proper timing perception, learning, memory, choice reaction time, and se q uence, c an perfectly mimic a two-channel very short-term memory. Obviously, this is not an tachistoscope. The shutter on one projector is exhaustive list of potential uses. In the programmed to open as the shutter on the other computer-controlled laboratory, the cathode ray projector closes. Thirdly, whereas a tachistoscope may terminal (CRT) or oscilloscope (CRO) may be used to be used to test one S at a time, a pair of projectors meet this need (Sperling, 1971 ; Van Gelder, 1972; simulating a tachistoscope may present material to Wojnarowski, Bachman, & Pollack, 1971). -
Cyanotype Detailed Instructions
Cyanotype Detailed Instructions Cyanotype Formula, Mixing and Exposing Instructions 1. Dissolve 40 g (approximately 2 tablespoons) Potassium Ferricyanide in 400 ml (1.7 cups) water to create STOCK SOLUTION A. Allow 24 hours for the powder to fully dissolve. 2. Dissolve 100 g (approximately .5 cup) Ferric Ammonium Citrate in 400 ml (1.7 cups) water to create if you have Chemistry Open Stock START HERE STOCK SOLUTION B. Allow 24 hours for the powder to fully dissolve. If using the Cyanotype Sensitizer Set, simply fill each bottle with water, shake and allow 24 hours for the powders to dissolve. 3. In subdued lighting, mix equal parts SOLUTION A and SOLUTION B to create the cyanotype sensitizer. Mix only the amount you immediately need, as the sensitizer is stable just 2-4 hours. if you have the Sensitizer Set START HERE 4. Coat paper or fabric with the sensitizer and allow to air dry in the dark. Paper may be double-coated for denser prints. Fabric may be coated or dipped in the sensitizer. Jacquard’s Cyanotype Fabric Sheets and Mural Fabrics are pre-treated with the sensitizer (as above) and come ready to expose. 5. Make exposures in sunlight (1-30 minutes, depending on conditions) or under a UV light source, placing ob- jects or a film negative on the coated surface to create an image. (Note: Over-exposure is almost always preferred to under-exposure.) The fabric will look bronze in color once fully exposed. 6. Process prints in a tray or bucket of cool water. Wash for at least 5 minutes, changing the water periodically, if you have until the water runs clear. -
Enlarger / Photogram Review Worksheet Photography 1 Ms. Brown Names Block Date
Enlarger / Photogram Review Worksheet Photography 1 Ms. Brown Names Block Date Find your enlarger partner and work as a team to fill out the following handout. 1. It is safe to have your photo paper out of the box/bag while you focus the enlarger light. a. True, photo paper is light sensitive but not THAT sensitive. b. False, photo paper is light sensitive and should never be left out or opened when any kind of white light is present in the darkroom or classroom, which is why you turn your timer OFF while you get out your paper. 2. Please explain why we make “test strips” in photography. 3. What should you consider for your photogram composition? a. Asymmetry b. Movement c. Full range of values including true black and true white d. Strong focal point e. All of the above 4. A PHOTOGRAM is also known as a RAYOGRAM named after the artist MAN RAY. a. True b. False 5. What is the difference between “focus” and “time” on your timer? Please explain. 6. What number enlarger are you assigned to? _____ 7. Find your assigned enlarger and write down the apertures (f-stops) from brightest to dimmest. (hint…apertures are located on the lens of your enlarger) BRIGHEST (2.8) ------------------------------------------------------------------- (32) DIMMEST 8. Turn your aperture (f/stop) to the brightest setting. Now set your aperture to f/8. How many clicks does it take to get to f/8 on YOUR enlarger? (This will vary depending on the brand of your enlarger) _______ BEFORE YOU BEGIN WORKING IN THE DARKROOM TODAY. -
Ground-Based Photographic Monitoring
United States Department of Agriculture Ground-Based Forest Service Pacific Northwest Research Station Photographic General Technical Report PNW-GTR-503 Monitoring May 2001 Frederick C. Hall Author Frederick C. Hall is senior plant ecologist, U.S. Department of Agriculture, Forest Service, Pacific Northwest Region, Natural Resources, P.O. Box 3623, Portland, Oregon 97208-3623. Paper prepared in cooperation with the Pacific Northwest Region. Abstract Hall, Frederick C. 2001 Ground-based photographic monitoring. Gen. Tech. Rep. PNW-GTR-503. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 340 p. Land management professionals (foresters, wildlife biologists, range managers, and land managers such as ranchers and forest land owners) often have need to evaluate their management activities. Photographic monitoring is a fast, simple, and effective way to determine if changes made to an area have been successful. Ground-based photo monitoring means using photographs taken at a specific site to monitor conditions or change. It may be divided into two systems: (1) comparison photos, whereby a photograph is used to compare a known condition with field conditions to estimate some parameter of the field condition; and (2) repeat photo- graphs, whereby several pictures are taken of the same tract of ground over time to detect change. Comparison systems deal with fuel loading, herbage utilization, and public reaction to scenery. Repeat photography is discussed in relation to land- scape, remote, and site-specific systems. Critical attributes of repeat photography are (1) maps to find the sampling location and of the photo monitoring layout; (2) documentation of the monitoring system to include purpose, camera and film, w e a t h e r, season, sampling technique, and equipment; and (3) precise replication of photographs. -
Photographic Films
PHOTOGRAPHIC FILMS A camera has been called a “magic box.” Why? Because the box captures an image that can be made permanent. Photographic films capture the image formed by light reflecting from the surface being photographed. This instruction sheet describes the nature of photographic films, especially those used in the graphic communications industries. THE STRUCTURE OF FILM Protective Coating Emulsion Base Anti-Halation Backing Photographic films are composed of several layers. These layers include the base, the emulsion, the anti-halation backing and the protective coating. THE BASE The base, the thickest of the layers, supports the other layers. Originally, the base was made of glass. However, today the base can be made from any number of materials ranging from paper to aluminum. Photographers primarily use films with either a plastic (polyester) or paper base. Plastic-based films are commonly called “films” while paper-based films are called “photographic papers.” Polyester is a particularly suitable base for film because it is dimensionally stable. Dimensionally stable materials do not appreciably change size when the temperature or moisture- level of the film change. Films are subjected to heated liquids during processing (developing) and to heat during use in graphic processes. Therefore, dimensional stability is very important for graphic communications photographers because their final images must always match the given size. Conversely, paper is not dimen- sionally stable and is only appropriate as a film base when the “photographic print” is the final product (as contrasted to an intermediate step in a multi-step process). THE EMULSION The emulsion is the true “heart” of film. -
Color Printing Techniques
4-H Photography Skill Guide Color Printing Techniques Enlarging Color Negatives Making your own color prints from Color Relations color negatives provides a whole new area of Before going ahead into this fascinating photography for you to enjoy. You can make subject of color printing, let’s make sure we prints nearly any size you want, from small ones understand some basic photographic color and to big enlargements. You can crop pictures for the visual relationships. composition that’s most pleasing to you. You can 1. White light (sunlight or the light from an control the lightness or darkness of the print, as enlarger lamp) is made up of three primary well as the color balance, and you can experiment colors: red, green, and blue. These colors are with control techniques to achieve just the effect known as additive primary colors. When you’re looking for. The possibilities for creating added together in approximately equal beautiful color prints are as great as your own amounts, they produce white light. imagination. You can print color negatives on conventional 2. Color‑negative film has a separate light‑ color printing paper. It’s the kind of paper your sensitive layer to correspond with each photofinisher uses. It requires precise processing of these three additive primary colors. in two or three chemical solutions and several Images recorded on these layers appear as washes in water. It can be processed in trays or a complementary (opposite) colors. drum processor. • A red subject records on the red‑sensitive layer as cyan (blue‑green). • A green subject records on the green‑ sensitive layer as magenta (blue‑red). -
Making the Transition from Film to Digital
TECHNICAL PAPER Making the Transition from Film to Digital TABLE OF CONTENTS Photography became a reality in the 1840s. During this time, images were recorded on 2 Making the transition film that used particles of silver salts embedded in a physical substrate, such as acetate 2 The difference between grain or gelatin. The grains of silver turned dark when exposed to light, and then a chemical and pixels fixer made that change more or less permanent. Cameras remained pretty much the 3 Exposure considerations same over the years with features such as a lens, a light-tight chamber to hold the film, 3 This won’t hurt a bit and an aperture and shutter mechanism to control exposure. 3 High-bit images But the early 1990s brought a dramatic change with the advent of digital technology. 4 Why would you want to use a Instead of using grains of silver embedded in gelatin, digital photography uses silicon to high-bit image? record images as numbers. Computers process the images, rather than optical enlargers 5 About raw files and tanks of often toxic chemicals. Chemically-developed wet printing processes have 5 Saving a raw file given way to prints made with inkjet printers, which squirt microscopic droplets of ink onto paper to create photographs. 5 Saving a JPEG file 6 Pros and cons 6 Reasons to shoot JPEG 6 Reasons to shoot raw 8 Raw converters 9 Reading histograms 10 About color balance 11 Noise reduction 11 Sharpening 11 It’s in the cards 12 A matter of black and white 12 Conclusion Snafellnesjokull Glacier Remnant. -
Lenses and Optical Instruments
INSTITUTE FOR NANOSTRUCTURE - AND SOLID STATE PHYSICS LABORATORY EXPERIMENTS IN PHYSICS FOR ENGINEERING STUDENTS HAMBURG UNIVERSITY , JUNGIUSSTRAßE 11 Lenses and optical instruments 1. Basic Theory The aim of this experiment is to determine the focal lengths of several different lenses. Afterwards we will use these lenses to build some simple optical instruments. First, we consider image formation by thin lenses. The relationship between the focal length f of a lens, the object distance g, and the image distance b determines the ratio of the image height B to the object height G. In Fig. 1 the two right-angled triangles on the left and right sides of the lens are similar. Figure 1: Construction to find the image position (1) for a thin lens using three principal rays: i.e. the = = focal-, parallel-, and central rays. − We can rearrange this equation to get the lens equation for thin lenses: 1 1 1 or . (2) = + = + The imaging behavior of the lens depends on whether the object is located outside the first focal point, at the focal point, or inside the focal point, as shown in this table: Object Image Position g Type Position Orientation Relative size ∞ real b = f -/- point ∞ > g > 2 f real f < b < 2f inverted demagnified g = 2 f real b = 2f inverted equal size f < g < 2 f real ∞ > b > 2f inverted magnified g = f ∞ g < f virtual |b| > g upright magnified 1 Lenses and optical instruments 2. Experimental Procedure 2.1 Determining the focal length of a lens Measuring image and object distances. In this experiment the focal lengths of two different converging lenses are to be determined by measuring the image distance b and object distance g (see Fig.1) for each lens. -
Moving Pictures: the History of Early Cinema by Brian Manley
Discovery Guides Moving Pictures: The History of Early Cinema By Brian Manley Introduction The history of film cannot be credited to one individual as an oversimplification of any his- tory often tries to do. Each inventor added to the progress of other inventors, culminating in progress for the entire art and industry. Often masked in mystery and fable, the beginnings of film and the silent era of motion pictures are usually marked by a stigma of crudeness and naiveté, both on the audience's and filmmakers' parts. However, with the landmark depiction of a train hurtling toward and past the camera, the Lumière Brothers’ 1895 picture “La Sortie de l’Usine Lumière à Lyon” (“Workers Leaving the Lumière Factory”), was only one of a series of simultaneous artistic and technological breakthroughs that began to culminate at the end of the nineteenth century. These triumphs that began with the creation of a machine that captured moving images led to one of the most celebrated and distinctive art forms at the start of the 20th century. Audiences had already reveled in Magic Lantern, 1818, Musée des Arts et Métiers motion pictures through clever uses of slides http://en.wikipedia.org/wiki/File:Magic-lantern.jpg and mechanisms creating "moving photographs" with such 16th-century inventions as magic lanterns. These basic concepts, combined with trial and error and the desire of audiences across the world to see entertainment projected onto a large screen in front of them, birthed the movies. From the “actualities” of penny arcades, the idea of telling a story in order to draw larger crowds through the use of differing scenes began to formulate in the minds of early pioneers such as Georges Melies and Edwin S. -
American Scientist the Magazine of Sigma Xi, the Scientific Research Society
A reprint from American Scientist the magazine of Sigma Xi, The Scientific Research Society This reprint is provided for personal and noncommercial use. For any other use, please send a request to Permissions, American Scientist, P.O. Box 13975, Research Triangle Park, NC, 27709, U.S.A., or by electronic mail to [email protected]. ©Sigma Xi, The Scientific Research Society and other rightsholders Engineering Next Slide, Please Henry Petroski n the course of preparing lectures years—against strong opposition from Ibased on the material in my books As the Kodak some in the artistic community—that and columns, I developed during the simple projection devices were used by closing decades of the 20th century a the masters to trace in near exactness good-sized library of 35-millimeter Carousel begins its intricate images, including portraits, that slides. These show structures large and the free hand could not do with fidelity. small, ranging from bridges and build- slide into history, ings to pencils and paperclips. As re- The Magic Lantern cently as about five years ago, when I it joins a series of The most immediate antecedent of the indicated to a host that I would need modern slide projector was the magic the use of a projector during a talk, just previous devices used lantern, a device that might be thought about everyone understood that to mean of as a camera obscura in reverse. Instead a Kodak 35-mm slide projector (or its to add images to talks of squeezing a life-size image through a equivalent), and just about every venue pinhole to produce an inverted minia- had one readily available.