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FORENSIC PHOTOGRAHY

FORENSIC PHOTOGRAHY. What is the SLR FUNCTIONS. SLR is a single lens reflex camera. The natural light enters inside the camera, this light is then reflected off the hinged mirror that is found inside the camera, onto a pentaprism of mirrors.

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FORENSIC PHOTOGRAHY

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  1. FORENSIC PHOTOGRAHY

  2. What is the SLR FUNCTIONS SLR is a single lens reflex camera. The natural light enters inside the camera, this light is then reflected off the hinged mirror that is found inside the camera, onto a pentaprism of mirrors. This enables the user of the camera to view what the camera is pointed at, once the shutter release button is pressed, the camera immediately goes up, this then reflects the light to allow the light to shine onto the silver halide film or a charged coupled device (known as CCD) at the back of the camera.

  3. HOW IS A IMAGECREATED: Using Wet Photography: There is a chemical called ‘silver halide’ this is used to cover the film due it being sensitive to the light. The light that is projected through the lens, reflects off the mirror, and it burns the image onto the film, then this creates ‘negative’. The sensitivity is dependent on the ISO number that is found on the film,

  4. HOW IS A IMAGE CREATED: CCD: Using Digital Photography: Digital Photographers use charged coupled device (CCD) to gather images. When the light is reflected onto the device it creates a charge. This charge then converts the light photons into the electrons producing pixels. These pixels consist of red, green and blue blocks (the are the 3 primary colours). The size counts for the quality, the size of the CCD dictates the amount of photons that can be converted into electrons. Therefore the more photons that can be collected the more pixels can be produced, creating a clearer, sharper image. Pixels of Big CCD: Pixels of Small CCD:

  5. Pixel Colours are red, blue and green.

  6. STORAGE ON A CCD: JPEG is stands for joint photographic experts group. RAW is a picture format that is used in JPEG, the RAW is able to obtain all of the data within the image. JPEG also losses images because of the some data when being processed, due from the CPU within the camera.

  7. HOLD THE CAMERA: the shutter is depending on how good the image is to be, if the camera was to be move the image will look not as good, because when the light reflex the mirror and the mirror collects the image, then if the camera isn’t steady then the image wont look good. So a tripod and a monopod will be helpful to prevent this form occurring. Monopod: Tripod:

  8. DEPTH OF FIELD Depth of field is the amount of the distances of the picture that the image appears to be sharp/clear.

  9. Depth Of Field - AFFECTING FACTORS DOF lets you focus on one main image, for example on this image to the side it shows snooker balls, now this camera is focused on the ball1, the DOF help at the crime scene so that you can focus on to on peace evidence. APERTURE = F5.6

  10. CRIME SCENE 1 : (LIVING ROOM: FLUORESCENT LIGHTING AND REFELCTIVE SURFACES) • the F16 is used in order to keep every object in the room in focus, as it has good DOF. • The shutter speed could be up to 1/125th second. If the shutter speed was so it will cause a overexposed. • The ISO can be set to 200 as it will create a sensitive image and it will prevent noise. • To be able to see the whole image, the lens needs to be set as 18-55mm.

  11. CRIME SCENE 2: (EXTERNAL VIEWS ON AN OVERCAST DAY) • the F16 has a great DOF. • Since the image of the weather isn’t good the shutter speed 1/30th second, this speed can be used as the camera needs to let enough light into the camera to avoid the image being underexposed. • ISO 400 would be recommended to be used as it is more sensitive and will help to take this image. • To be able to see the whole image, the lens needs to be set as 18-55mm.

  12. CRIME SCENE 3 – CLOSE-UP VIEWS OF FINGERMARKS IN BLOOD • The F4 is used as a wider aperture, because the image is close there is no point of worrying of the DOF. the aperture could be placed on a low setting to allow more light into the camera. • The shutter speed is 1/5th second, this can be used to enable natural light exposure. • ISO 100 could be used to obtain the high level of detail in the finger mark. The ISO will also make the image clearer/sharp. • To be able to see the whole image, the lens needs to be set as 18-55mm.

  13. EQUIPMENT USES • Macro Lens Attachments; this is Good for closing up to images, the image being viewed through a camera, giving a closer view of the an image. • Ring Flash – this is good for closing up to images and reflects the surface, as it lights up, the area that is around the object rather than the object only. This is preferred indoor and will work better indoors.

  14. EQUIPMENT USES • Tripod; the tripod prevents the camera from getting blurry images, and instead getting good images because the camera is held properly in shape by tripod. • Wide Angle Lens Attachment: Widens the cameras make the camera capture more of an image and the image. It works good indoors and out.

  15. EQUIPMENT USES • Speed Light Flash Gun: this allows to take a picture if the home or place that is dark and not visible, this gun will reflect the light and will shot back to the camera, better for indoor. • Ultra Violet Lens Filter: this lens reduces the amount of light, that enters the camera, so this helps to prevent the overexposure of light, this is better for outdoors in a sunny day, the weather could cause overexpansion of light.

  16. EQUIPMENT USES • Polarising Lens Filter: is used to filter the light, saturating the image by removing reflections that is not needed. Works better for indoor.

  17. reference http://www.google.co.uk/search?hl=en&q=images&bav=on.2,or.r_gc.r_pw.r_qf.& http://mattstow.com/fireworks.html http://www.google.co.uk/imgres?q=ccd&um=1&hl=en&safe=active&biw=1280&bih http://en.wikipedia.org/wiki/Charge-coupled_device (for image) http://theme.wordpress.com/themes/avid/ http://www.google.co.uk/search?hl=en&sugexp=les%3B&pq=dark+images+& http://www.google.co.uk/search?hl=en&sugexp=les%3B&pq=dark http://www.istockphoto.com/article_view.php?ID=109

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