Forensic Photography

a. Stop down the aperture or narrow the aperture (larger f-number)

The primary exposure setting is the aperture of the lens. The aperture is the hole in the back of the lens, allowing light into the camera. A broader or larger aperture will increase the light amount let into the camera, making it easier to expose the image. However, it creates a shallow depth of field in the image, which calls for the use of the small or narrow aperture to create the full depth of field. Robinson (2012), state that the aperture of the lens should be controlled to accommodate the depth of the field. However, the smaller aperture has some problems. Like having slow shutter speed due to the significant restriction of light to the camera and diffraction created when light spreads from the small aperture to the digital sensor. Nonetheless, that can be resolved by using the tripod. Therefore, using the narrower aperture should be used for the maximum depth of field on the image.

b. Know the hyper focal distance or move further from the subject

The hyper focal distance is the closest one can be when focusing on an object and still obtain a sharp background. In various circumstances, it shows when one can use the larger aperture and still have the images sharp (Robinson, 2012). The sharpness of the image requires that one moves further from the object to obtain that focal point that suite the f-number of the camera. The distance widens the area and thus the depth of field. The closer the object is to the camera, the shallower the depth of field. Thus, taking a long distance to the camera deepens the depth of the field.

c. Shorten the focal length

The visual properties of the lens provide either the greater depth of field or shallower depth of field. The focal length is the lens capability to magnify a distant object image. The focal length needs to be shorter to attain a deeper depth of field. The longer one sets the focal length, the shallower the field depth.

d. Use of a tilt-shift lens

The specialty lens, tilt-shift lens, one can tilt the field of focus to match the terrain in the image. The tilt helps even with the broader aperture that would otherwise make a shallower depth of field.

Question 2

The automatic focusing cameras cost more than the manual focusing, which would mean they are better than the manual focusing. However, the automatic focusing cameras are just an upgrade of the manual focusing. Besides, some cases would be better with the manual focusing than the automatic focusing. The examples for such cases include:

1. Where there is a lack of sharp horizontal or vertical lines present in a particular scene, the use of automatic focusing will not be viable. In the case of a plain wall and a hole, the automatic focusing will have the searching without making the object capture (Robinson, 2012). In depressing the shutter button, nothing happens as the camera finds nothing to focus on. Using the manual focusing enables the photographer to adjust to what they need and take the picture.
2. Where there are two different well-defined objects in different ranges in the field of view, the camera may decide to focus on the nearer or the further object when one needed otherwise (Robinson, 2012). The manual focusing offers the opportunity to decide on the object in which one requires to get on the picture.

Question 3

Setting exposure compensation dial to +1 resets the ISO setting to 50 ISO. The reset 50 ISO film is slower film and is less light sensitive. Therefore, the film will need more light to have proper exposure. The 50 ISO film would need precisely 1stop more light needed by the 100 ISO speed film. Where 100 ISO film required 1/60th of second shutter speed with f/16, 50 ISO will need 1/60th of a second speed with the aperture being f/11 (Robinson, 2012). On changing the exposure from f/16 to f/11, the exposure changes by +1. In this, the camera is fooled to think that it is at ISO 50 when it is still at ISO 100. In this, the exposure changes by +1 when the camera is still at ISO 100. In the shutter priority exposure mode, achieving a real change in exposure comes from fooling the camera about the ISO that is loaded in the camera.

Question 4

The f/16 sunny day rule states that the shutter speed is the inverse of the ISO value on a sunny day and the aperture of f/16 (Robinson, 2012). The rule translates to the shutter speed being 1/100 seconds on a sunny day, aperture f/16, and ISO100. The rule takes the rule of the thumb.

Question 5

The depth of the field requires resolution. The smaller the detail size of the object, the higher the spatial frequency needed to be resolved, and that will also mean a smaller DOF the lens can produce (Robinson, 2016). The DOF is usable in determining the actual performance of the lens over the specified depth of field at a specific detail size.

The changes in the f/# affect the depth of the field. Changing f# of the lens will affect the depth of the field such that as the objects move away from the best focus position, the details of the objects move into the apertures more full area (Robinson, 2016). The wider the aperture spreads, the more information the information from a distance becomes blurred into all the other information around the object. The f/# of the lens controls the expansion of the cone; therefore, it controls the information or details that are blurred together at a given distance.

Question 6

With the 8mp camera (3264 X 2448 pixels), capturing 10.88’’ of the detail in the viewfinder will result in a full resolution print. However, one should limit themselves to the 10.88” of the world in the viewfinder. Trying to include greater than 10.88” of the subject matter in the subject matter in one image will be losing the capability of the camera (Robinson, 2016). In case of filling the frame with an object 12”, the object will spread over the 3264 pixels out over 12”, resulting in 272ppi or the equivalent of just under 5mp camera. Thus, in taking the image of 12”, the optimal way of photographing will be by taking the photograph of two 7” overlapping images. Conversely, filling the frame with an object less than 10” long, one will be spreading the 3264 pixels over 8” (using 8”). The result will be 408ppi, which is equivalent to the 11.1mp camera.

Reference

Robinson, E. M. (2012). Introduction to Crime Scene Photography. Academic Press.Robinson, E. M. (2016). Crime scene photography. Academic Press.