Camera Exposure Questions & Answers

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Exposure is a big and sometimes mysterious part of photography, but once you understand the basics of it, you'll be able to easily navigate all the ins and outs of the topic. There are many variables that can have an impact on the ultimate exposure of a photograph, so learning as much as possible about lighting and how your camera reacts to it is critical.

In today's post, I'll be answering 18 very common questions budding and amateur photographers oftentimes ask about exposure and how it relates to cameras and photography. After reviewing what I share in this post, if you have any questions of your own, please don't hesitate to ask down below. I'd be happy to help any way I can. Also, if you would like to contribute your own knowledge to this topic, feel free to do that down below as well.

Exposure Questions & Answers​

Q: What's the fastest typical available shutter speed in a DSLR camera?

A: On most cameras, the fastest shutter speed available is 1/4000th of a second. I just confirmed this on my Canon Rebel T7i.

Q. What type of exposure meter is built into the average camera?

A. It's a reflective meter. Inside a camera, a reflective meter measures the amount of light that bounces off whatever it is you're taking a photograph of and lands back on the meter itself. If your subject is bright or brightly colored, more light will bounce off of it and land on the meter. If your subject is dark, less light will reflect to the camera.

Q: Which common camera metering mode would be most beneficial when attempting to gauge the light that bounces off a very specific area in a scene?

A: Spot metering. Read more about spot metering here. With this type of metering, the camera measure only a very small portion of the center of a scene.

Q: What visual effect becomes more pronounced with higher ISO values?

A: Noise, sometimes referred to as grain, becomes more and more pronounced the higher the ISO setting on a camera goes. Camera ISO amplifies the sensitivity of the sensor and with that amplification comes electronic artifacts that find their way into photographs. Generally, you can increase the ISO value to about 800 without introducing much noise, but higher than that, you'll begin noticing small randomly shaded specks in your photos. Read more about noise and grain here.

Q: What climactic condition softens shadows in a scene?

A: Mist will oftentimes soften shadows in a scene. Because each particle of liquid contained in mist reflects light, any light that hits the mist will be scattered, reducing the ability of that light to bear down harshly on a subject in a scene.

Q: What ISO setting results in the least amount of noise?

A: Lower ISO settings introduce the least amount of digital grain to a photograph. The lower the ISO, the less the light touching the sensor will be amplified and the less pollution there will be. For most cameras, including Canon and Nikon, the lowest base available ISO will be 100. For some older models of camera, the lowest ISO is 200. The newer Nikon D810 offers an ISO that goes all the way down to 64.

Q: A spot meter typically measures what percentage of light in a scene?

A: Since spot metering only measures a very small area at the center of a scene, the percentage will be between 1-5%. Other metering methods, such as evaluative, partial, and center-weighted average measure much larger areas. Read more about spot metering here.

Q: A scene that has higher than average reflectivity can cause what type of exposure?

A: In general, when a scene is very bright, a camera will react by darkening down the exposure (oftentimes too much), resulting in an underexposed photograph. This is particularly true with mixed lighting situations. If there's a very bright area of a scene, such as the sun, a light bulb, or a window with daylight streaming through it, the camera will overreact to compensate and will underexpose all other elements of the scene. The best way to deal with this is to use exposure compensation or one of the more restrictive metering methods, such as spot metering or partial metering.

Q: What do you risk when hand-holding a camera while using a slow shutter speed?

A: Depending on how slow your camera's shutter speed is, you can risk introducing blur into your photos due to camera shake. To avoid this type of blur, be sure to use the appropriate shutter speed for your focal length. The rule is to use the reciprocal of your focal length for your shutter speed. So if you're shooting with a 50mm prime lens, then use at least a 1/50th of a second shutter speed. Learn more about camera shake here.

Q: A histogram that is skewed to the left is an indication that a photo or scene is underexposed or overexposed?

A: A left leaning histogram usually means that the image is underexposed. I say usually because that's not always the case. Sometimes photographers capture scenes in creative manners and want very specific amounts of light in the shots. If this was the case, a photographer certainly wouldn't want to edit an image in post-processing so the histogram is more centered. To see what a histogram in Adobe Camera Raw looks like, check out this post.

Q: The longest available shutter speed on a DSLR camera is what?

A: In general, the longest available shutter speed for most cameras is 30 seconds. That can be extended by using remote shutter buttons and a feature called bulb mode. Bulb mode is an option that's available on some cameras that allows for any length of shutter speed, whether it be one minute, 20 minutes, or an hour.

Q: The lowest ISO setting on a camera is known as...?

A: The lowest ISO setting is known as base ISO.

Q: Which metering mode usually is set by default on most cameras?

A: Evaluative metering is set by default on most cameras because it's a general purpose mode that takes into account the lighting of the entire scene. This type of metering is appropriate for most types of photography.

Q: What would you need to do to freeze movement in a photograph?

A: The faster the shutter speed, the more frozen time will appear in a photo. Just how frozen time will appear will depend on how fast the objects in a scene are moving. A good rule of thumb is to set your camera to 1/250th of a second to freeze most action shots. Remember though, for some much faster moving subjects, you may need to increase the shutter speed substantially. Think about the wings of a hummingbird. You may need to increase your camera's shutter speed to something like 1/1000th or 1/2000th of a second to freeze the wing motion.

Q: Increasing the size of your lens's aperture by one stop has what type of effect?

A: By increasing the size of a lens's aperture, you're letting more light travel through the lens. For each stop in photography, you're either halving or doubling the amount of light that reaches the camera's sensor. In this case, since the aperture size is being increased by one stop, twice as much light would travel through.

Q: Center-weighted metering measures what percentage of light in a scene?

A: Center-weighted average metering assigns the most weight to the center of a scene and then that weight begins to fade as it moves outward. In general, this metering mode will measure approximately 60-80% of the available light in a scene.

Q: When highlights are pure white in a photo, they're considered what?

A: The phrase used in photography for areas of an image that are pure white is burned out. This means that those areas of a scene were too bright to assign any data to.

Q: What aspect of a digital sensor is controlled by ISO?

A: ISO controls a camera sensor's sensitivity to light and color. The higher the ISO value, the more sensitive the sensor is. Think of it as an amplifier for a home or car stereo. It takes what's already available and boosts it up.
Camera Exposure Questions & Answers was posted on 06-03-2021 by 15Katey in the Photography forum.

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