Single Lens Reflex Cameras and Manual Mode
The Nikon D3300 on Amazon

Wikipedia's very complete article on aperture

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Digital single-lens reflex cameras let the photographer see right through the camera's lens. They have a mirror that sits in front of the sensor and that reflects light upward from the lens to a prism that bounces the light up to a little eyeball-size viewer for the photographer to see and frame the image before snapping the photo. When the shutter is pressed, the mirror flips up out of the path of the light so it can then fall on the sensor (the source of the familiar click sound associated with shutter release.) SLRs were developed in 1861 because viewers in cameras of those early days were aimed at a specific point in front of the camera and so caused framing problems if the subject were beyond or in front of that point. These days, point-and-shoot cameras are very popular because of all the automatic features. They make photography easy and accessible for anyone who wants to snap a shot. Besides an old-style viewer, today's cameras, like the Canon PowerShot and Nikon Coolpix, have a little LCD screen on the back that give the photographer two ways to frame the shot before pressing the shutter and so a good idea of the image-to-be.

But automatic features, controlled by the camera's onboard processor mean that decisions like shutter speed and amount of light to be used (via aperture setting) are taken out of the photographers's control. At some point photographers want to take charge of these settings and this is where SLRs shine. A good camera for folks at this point in their career is the Nikon D3300, which costs around $500 when purchased new as a kit that includes Nikon's 18-55mm zoom starter lens. Like all SLRs, it has a dial near the shutter that lets the user choose the shooting mode. Mode choices include:

• AUTO – Point-and-shoot mode
• GUIDE – Walks you through shooting situations using text and diagrams on the LCD screen
• A – Aperture Priority mode... you set the aperture and the camera automatically sets the shutter speed for best exposure
• S – Shutter Priority mode... you set the shutter speed and the camera automatically sets the aperture for best exposure
• M – Manual mode... you set the aperture AND shutter speed allowing exposure and field of focus possibilities

Aperture, shutter speed and exposure
Camera lenses have an adjustable opening close to the end where the lens mounts on the camera. The wider the opening, the more light reaches the sensor and vice versa. Extra light on the sensor means that the shutter speed will have to be quicker, or the resulting image will be over-exposed. Closing the aperture down means less light and a longer shutter duration is then necessary to avoid under-exposure. But decreasing aperture size also increases the depth of the field of focus, and vice versa. For this reason, you usually set the aperture according to the kind of photo you want, and then set the shutter speed to get the exposure just right. At the bottom of the camera's viewer area, there's an exposure meter used for this purpose and you move the shutter speed up or down as needed. “Perfect” exposure is in the center of the meter's scale with a few over- and under-exposure settings left and right of center respectively.

Field of focus and kinds of photo
The camera's viewer window also includes a dot that you place on the subject or “star” of your photo, for example on the baby's nose. Push the shutter button halfway down. Autofocus takes over (or not if it's turned off or just absent) and the focus ring of the lens rotates and the baby's face comes into focus. Then you push the shutter button all the way down and snap the photo. If the aperture is set very open, only baby's nose will be in sharp focus, or maybe from his nose back to his ears, but not his hair towards the back of his head. Points forward of and behind the point of focus will vary gradually from softer focus to totally out of focus. This can be a good way to de-emphasize the less important parts of the composition. Want all of the baby and maybe his pals in front of and behind? Set the aperture towards the middle of its range.

For landscape photography, it's good to have a deep field of focus. You'll want some elements of the composition in focus in the foreground, the main subject medium deep and in very good focus, and some stuff in the background fading to out-of-focus. Set the aperture towards the closed end of its range. For more information on aperture and field of focus, click the link at the left for Wikipedia's article on aperture.

There are some very good books available that can help a novice photographer get the most out of a single lens reflex camera. Check out those by Scott Kelby first.
March 13, 2015

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