Measuring Light Intensity

The Inverse Square Law demonstrates the distance between an object and the light array needed to display the object. By moving the camera or object further away you will need more light to display the object within the same lighting as the closer photograph. To balance the light needed for the photograph you must calculate the difference between a close light array and a far light array. From a   starting point of light every time the object movement is doubled the light source must be quadruple. Most often the amount of light that you started with is not enough for the finished product that is located further from the camera than the first photograph. In general you will multiply the starting point by 4 for every movement twice the distance away from the original light setting.

As you can see in the two upper demonstrations of the Inverse Square Law  that as the light travels out ward it is dispersed among the area and the intensity of the light becomes less. By making calculations to increase the amount of light needed you will provide the proper amount of light to take your photograph.  The easiest way to perform the light calculation is to times the distance by 4. It is important to have the proper amount of light; lets take for example that you have a subject that is 4 ft from the camera you then move the subject double the distance away from the camera then the light calculation would be 16d thus the calculation would be  4*4 , next move the subject 4 more ft and the calculation would be 4*4*4 equaling 64 so it would be 64d and so on and on to quadruple the light array as the object moves further from the camera.      

The flash can have an adverse effect on a subject when used improperly the flash array is able to submit the  subject to too much light in retrospect producing a glair or it could not light the subject at all if the objective is located  too far away from the flash.  Some of the issues with the flash are how powerful the flash is when actuated. Most flash cameras will not be able to take pictures telescoping over 300 meters. This presents problems with taking surveillance in dark areas camera such as hall ways and under bridges. Some other variables that you must look at are areas that do not refract light, hills, pictures located on wet surfaces and photographs where the subject blends in with the surrounding area in these instances you must choose a special procedure in order to take proper precautions producing the correct lighting balance for the photograph.  Other issues you may have when photographing in dark areas are tight places that do not allow enough space to get the view of the whole subject. In the case of a tight area you may want to take the photograph from a ladder or tripod located close to the object. 

References:

http://hyperphysics.phy-astr.gsu.edu/hbase/vision/isql.html

http://www.geofflawrence.com/photography_tutorial_inverse_square_law.htm

http://www.energybooks.com/pdf/D1150.pdf

http://www.media-wareness.ca/english/resources/educational/lessons/secondary/television_radio/camera_shots.cfm

http://dpanswers.com/content/nikon_flash_use03.php

A History Of Photography

Photography has been around since the early 1800’s. For the last two hundred and ten years since the first photograph until now the digital camera age photographs and motion picture have advanced industrialization of the world from sales catalogs to internet sales, photographing of crime scenes and objects found at the crime scene give a new meaning to a picture is worth a thousand words.

 Some may argue about when the first picture was taken just as sand stone and shall makes fossil impressions the first photograph was made by Nicephore Niepce the father of photography in 1825, Nicephore  Niepce created a method for photography that used a piece of copper and placed bitumen over the copper. The copper cutout is exposed to light and makes an image which is transferable to paper. Nicephore Niepce took his first photograph of a stile picture of a man holding a horse by its straps this photograph go’s for about 300,000 dollars in today’s market. In 1826  Nicephore Niepce took the second picture the first of a real scene.

In 1838 The first human in a photograph was taken by Louis Daguerre the inventor of the Daguerreotype. The French government bought the Daguerreotype from Daguerre and released it to the public for free.

In 1840 the first Human subject was photographed  by William Henry Fox Talbot  the inventor of the negative and positive photographic processes, took a still picture of a man in front of a coach wagon.

In 1861 the first color photograph was taken by James Clerk Maxwell he photographed a ribbon three times using three different colored lenses then by projecting the tree colored pictures onto a screen all at the same time the light produced a color picture, once all three camera were lined up properly.

In1877 the first color landscape   was photographed by Louis Arthur Ducos Du Hauron who invented the subtractive (cyan, magenta, and yellow) color method. This pioneer in color photographs latter worked on the additive (red, green, and blue) color method.

In 1934 the modern 35 mm film was invented changing the way photography was taken. This film invented by Kodak could be loaded into the camera during broad day light with preloaded reels, the perforated edges that allowed the camera to click in to photo position made the 35 mm Kodak a better camera even though it  was expensive when it came out  costing $175  which is equal to $3,000  today.

Cameras have come a long way from a large photo machine to a little hand held camera the differences between the technology is astonishing. 

Digital cameras technology came about in 1951 from the same technology that recorded television called Video Tape Recorder (VTR). Later in the 1960’s NASA started to use digital cameras to take photos of the moon and the government used digital photography for spy surveillance.  Texas Instruments patented an electronic camera that used no film, in 1972 later in 1981 Sony released the Mavica electronic still camera it was the first commercial electronic camera, the photographs were recorded onto a Mini disc. The Mavica took video freeze frames so they did not consider it a true digital camera.

In 1987 Kodak released seven different products for manipulating still video images. In 1991 Kodak released the first digital camera system it was the Nikon F-3 Digital1.3 pixel camera Kodak marketed the camera for photojournalist.

The first consumer Digital cameras where the 1994 Apple Quick take 100,1995 Kodak DC-40,1995 Casio QV 11, and  1996 Sony Cyber Shoot digital  still camera.  All of which had the expensive binocular look to them.

Today quick point and shoot cameras are made for ease and fun they have less features to get in the way and make good photographs. It helps to have a quick point and shoot camera because they are easy to conceal and put into your pocket when you get finished taking photographs. These cameras are less expensive and add about the same quality as a larger more expensive digital camera. The one thing that these cameras do not have is the user ability to make camera adjustments that are needed in some conditions.

The DSLR (Digital Single Lens Reflex) cameras take straight even pictures better than the smaller quick point and shoot digital cameras making them a little more professional than the smaller cameras. The DSLR cameras have exchangeable lenses, external flash and optical view finders. The DSLR cameras tend to be bulkier, weigh more, and cost more than the single shoot cameras. You can buy a DSLR camera for less than a thousand dollars now days. Most people prefer smaller easier to use cameras that cost less when dropped, lost,or stolen the more costly larger cameras are mostly for enthusiast who like to take a professional picture every once in awhile.

Some of the improvements cameras have made in the Justice System are due to the fact that cameras are devices and do not lie. If you do not edit the pictures in an incorrect manner, the photograph evidence is labeled properly, and has correct chain of custody; a picture can prove to be a hard piece of evidence to defend against. Most prosecution use pictures as supportive evidence to let the jury know that that they have no doubt of who committed the crime and the investigation tells the jury why. As evidence goes photographs are quicker and easy to display unlike video tapes and surveillance cameras. 

Reference

http://www.chemistryexplained.com/Ny-Pi/Photography.html

http://listverse.com/2009/01/13/top-10-incredible-early-firsts-in-photography/

http://photo.net/history/timeline

http://www.articlesbase.com/digital-photography-articles/the-different-methods-of-photography-1844887.html

http://www.infoborder.com/Digital_Camera_History/

http//www.yahoo.com/images 

Best Practices For Photographing A Crime Scene

Best Practices for digital photography are procedures and rules that allow Crime Scene Investigators the ability to take clear meaningful photographs of items located at the crime scene. Four important photographs are explained fingerprints, shoe prints, tire marks, and bit marks.

Image resolution and clarity is a must, filling the frame is an important first step in taking good photographs. The digital cameras frame should be dedicated to the object improving both quality and size this makes for a better photograph by getting the highest quality view as possible.

When capturing finger prints and bite marks the lens should be set to the closet focusing distance. Next move the camera as close to the object as possible. Then capture the object in a precise one to one using the highest resolution.

Set the closes focusing distance by using the lens on the camera. Use by accurately calibrating the image by scale using Adobe Photoshop.

Capturing shoe prints and tire marks is a process that consists of taking full length photographs while filling the frame and adjusting the resolution for the sharpest image as possible.

It is correct to have image quality suggesting that you take pictures in segments that overlap then stitch or panorama the photographs together to provide an accurate view of the shoe print or tire marks.

These photographing techniques help the CSI agent take realistic photographs that represent objects as they appear at the crime (situ). The processes involved in best practices allow for the photograph examiner to see an actual representation of the object being photographed as close to its full size and length as possible.

References:

Crime Scene Photography Author: Edward M. Robinson with forward by Gerald Richards Publisher: ELSESEVIER Copy right: 2007

http://www.adobe.com/products/reader/pdfs/reader_user_guide.pdf

Depth of Field

Depth of field allows you to photograph the whole subject matter while keeping the actual focus on the single object. Many photographs will not allow you to take pictures of a single object with distractions in the way moving people, cars, trees, bushes, other photographers, it helps to find a good angle to take photographs from afar while keeping your objective centered. Some of the best pictures use depth of field for objects that either do not fit within regular lens size or need modification to view the whole subject matter. Magnification of the lens plays a big role in focusing  the camera to have depth  of field, another factor of depth of field are the f /stop setting they allow you to view the photograph in the correctly  lighting. Crime Scene investigators should not leave any object out of focus this technique is only used for photographers that take pictures for leisure or sales purposes. All photographs for Crime Scene Investigator must be in focus and directed to the subject matter. 

References:

http://www.cambridgeincolour.com/tutorials/depth-of-field.htm

http://www.photoxels.com/tutorial_dof.html

http://www.photoaxe.com/depth-of-field-photography-tutorial-part-3/

Night Photography Available Light

When photographing in dark places to add to the reflective surfaces it is suggested that you use a white card board or matte board, white projection screen, or a small white umbrella in order to catch light and refract it back to the camera.

Bracket your shoot, meaning take multiple photographs with different settings until you accomplish your goal. Take one shot at basic and then another shot with open lens.

Available light sources at night include:

·         Incandescent light

·         Halogen light

·         Mercury vapor

·         Fluorescent

·         Spot light

·         Arc light

·         Artificial light

Many SLR cameras have special flash settings for night view. Using an external meter such as a Gossen, it has the capability to read light from the moon and gives exposure based on natural gray card.

For special effects and movement photographs at night use a low power flash, make proper settings  f/4 and the back ground requires an exposure of 1/30, at F/2  and background requires an exposure of 1/8^th setting, shoot  as steady as possible.  

Having knowledge of how to work your camera is important, the user manual of the specific camera and flash allows you to know how to use your flash shader for moving objects. It is a nice feature to have an off the camera flash with night exposure settings that works by a remote system, this way you can move the flash lighting to the proper area to expose light from the background of the photographed object or person thus adjusting white light and soft light exposures producing a better photograph. 

Usage of the windows and door passages as a way to produce refractive light around the room is a good way of producing light in dark areas; using the white card board and white screen help make dark surfaces more refractive and noticeable. I know that the night settings and the built in moon light detection system in my Nikon D3000 works great but it only works properly with the SB 300 flash system.

References

Article by Robert Gorril Available Light and Night Photography in color and Black & White located at http://psa-newmember.org/firstyearhappenings/nightphotography/available-light.pdf also found at http://www.thefreelibrary.com/Available+light+and+night+photography%3A+in+color+and+black+%26+white.-a090219328