Fundamentals of Exposure

Fundamentals of Exposure

The reason you are reading this writing is probably because you don’t want to be distinguished as a point-&-shooter anymore. If you feel like your camera’s automatic mode or scene mode or best shot mode is intelligent enough to adjust the settings for proper exposure all the time, then you may discontinue reading now & more power to you. Owning a camera has now become a necessity more than a luxury as it was 10 years ago. I am so overwhelmed how popular the demand for photography simply by seeing most of our advanced gadgets today are equipped with a camera. I will be surprised if today’s teenager’s cell phone doesn’t have a built-in camera.

Since the emergence of digital cameras, the use of analog [film] faded to the obsolete side [but not totally]. With virtually unlimited shots per memory card [which by the way is reusable], you may go shoot as much as you can, at any occasion you are in anytime, anywhere.

So you had fun during shooting time, but the playback time isn’t as exciting. Unfortunately, out of the 400 photos you took during your Eurotrip, only a few of those are worthy for printing & hanging on your wall. This is very likely to happen when you always rely on your camera’s fully-automatic mode. It is indeed a fact that auto mode eliminates thinking on your part [making it easier to simply point-&-shoot], but just as the bumper sticker say, Actions may not always bring happiness, but there’s no happiness without action, you can’t expect a stunning photograph if you let the camera choose the settings for proper exposure [although it will still record an image, just not as commendable]. I would stare at an artist’s portfolio containing 20 entries the way I stare at a gorgeous young lady & look at a point-&-shooter’s photo album with 100 pictures the same way I skim on my 5-page insurance policy.

Aperture

Aperture refers to the diameter of the lens opening. Aperture is measured in a unit commonly called as f-stops. Other names for it are f-numbers, f-values, & aperture values. Don’t be confused as I will refer to these different names depending on their appropriateness of use in their respective context.

It is vital especially for beginners to keep in mind that the diameter of the lens opening is inversely proportional to aperture value. That is, as the f-number increases, the diameter of the lens opening narrows down & as the f-number decreases, the diameter of the lens opening becomes wider.

A versatile camera should have an aperture range of f-1.8 to f-16 or better. Such cameras have f-stops in these standard increments:

F1.8

F2.8

F4

F5.6

F8

F11

F16

Decreasing the aperture value from f-5.6 to f-4 is opening up the lens with 1 f-stop while increasing it from f-5.6 to f-f-8 is closing down the lens with 1 f-stop. Changing the aperture 1 f-stop down cuts the amount of light that passes through the lens into half. Changing it 1 f-stop up doubles the amount of light that passes through the lens.

A camera with lower minimum f-number is said to have faster lens. For instance, a camera with a minimum f-number of f-1.8 has faster lens than one with a minimum f-number of f-2.8. You may wonder why faster. Here’s an explanation. f-1.8 means wider lens opening than f-2.8, wider lens opening means more amount of light hits the lens, more amount of light hitting the lens allows the use of a faster [or shorter] shutter speed for proper exposure. This is especially ideal to freeze a moment without the blur.

A camera with higher maximum f-number is said to be more flexible. For instance, a camera with a maximum f-number of f-16 can utilize slow shutter speed better than a camera with a maximum f-number of f-11. Here’s why. f-16 means narrower lens opening than f-11, narrower lens opening means lesser amount of light hits the lens, lesser amount of light hitting the lens allows the use of a slower [or longer] shutter speed for proper exposure. This is especially ideal to depict motion such as the flowing water of Multnomah Falls.

Shutter speed

Another important component of a camera is the shutter. If the camera lens is the human eye, & the camera shutter is the eyelid. Then capturing an image can be done by blinking. This analogy is almost accurate. Let me elaborate on how it is slightly inaccurate about the last comparison. Humans by nature are awake and blinking means closing our eyelids to cover our eyes and reopening it back. On the other hand, camera shutter by default is closed & capturing an image means opening the shutter and closing it back to its default position. Having that explained, I won’t argue with anyone saying that taking a photograph is like inverse blinking.

Shutter speed as its name suggest controls the speed of the camera’s shutter, that is, the quickness of the open-close event. Unlike the aperture, shutter speed is not known by any other names. The unit for shutter speed is seconds [in case you haven’t guessed yet]. Although some special applications may require the shutter open for 1 second or longer, most of the everyday shots we take happen faster than a second, hence shutter speed is usually measured as fractions of a second.

Again, it is important especially for rookies to remember that the quickness of the shutter is inversely proportional to its numerical value. That is, as the value [in seconds] increases, the quickness of the open-close event decreases & as the value decreases, the quickness of the open-close event increases. A helpful reminder is that a fraction with larger denominator [the number below] is less than a fraction with smaller denominator provided the numerator [the number above] is constant.

In the shutter world, the numerator is almost always 1. Hence, it is easier to simply look at the denominator when changing shutter speed, keeping in mind that a higher denominator means faster shutter speed & a lower denominator means slower shutter speed.

A good camera should have a shutter speed range of 1 second to 1/2000 seconds. Such cameras have shutter speed in these typical increments [in seconds].

1

1/2

¼

1/8

1/ 15

1/30

1/60

1/125

1/250

1/500

1/1000

1/2000

Lately, some advanced & more sophisticated cameras offer shutter speed as slow [or as long] as 60 seconds. These devices perform better in lowlight conditions as they are capable of accumulating light longer.

A warning when using a slow shutter speed, use a tripod. A tripod is advisable for shots requiring a shutter speed of 1/30 or slower. I found that even those table-top mini tripods come in very handy. Here are some advantages of using a tripod:

1. It allows you to orient your camera for the composition [or framing] you desire

2. It prevents the camera from moving especially when the shutter is pressed.

3. It gives you the option to include yourself in the picture.

Even though the anti-shake or image stabilization technology is becoming very popular nowadays, they don’t emerge without limitations. The camera shake effect may happen if anything within the frame [or composition area] moves or if the camera itself moves. Camera shake effect due to the former can be tolerable or even produce more appealing pictures but camera shake due to the latter is hazardous to the photograph’s quality.

Using the 2-second automatic countdown timer [a thoughtful camera feature] helps avoid the unwanted blurriness due to camera shake since camera movement is inevitable especially the moment you press the shutter button [unless the camera is placed against a stable surface or a tripod]. There are several other factors that may help reducing or better yet eliminating camera shake. These are ISO [based on ASA] speed, white balance, exposure compensation, flash, & light metering. The camera shake effect becomes less visible as the shutter speed increases [e.g. 1/60 & faster]

A camera with a longer [or larger] maximum shutter speed is better as it allows flashless night photography and many other lowlight photographic applications.

A camera with shorter [or smaller] minimum shutter speed is better as it allows freezing of extremely fast moving subjects without using flash.

Recording Modes

Auto Mode

The phrase point-&-shooting refers to taking pictures in auto mode. In this mode, the camera determines every factor for proper exposure, the aperture value, shutter speed, ISO sensitivity, white balance, exposure compensation, flash firing, flash intensity, & light metering. Only the composition [or framing] is controlled by the photographer. Auto mode is widely used by the general public

Auto mode is useful when taking snapshots of moments where the photographer cannot afford the preparation time, snapshots of unexpected non-lasting circumstance, etc. You won’t get recognized for any photographic excellence but you may be rewarded if you happen to capture crime scene evidence.

This is the only mode where any pre-shot warning is likely not to show-up on your preview LCD screen [or viewfinder] since the camera always compensates for every single parameter affecting exposure. The sad truth is that the absence of pre-shot warnings does not guarantee a properly exposed photograph.

Semi-Automatic [or simply semi-auto] is divided in to 2 categories:

Aperture Priority mode

In the Aperture Priority mode, you select the aperture value & the camera determines the shutter speed for proper exposure when you press the shutter halfway. The camera’s choice of shutter speed is affected by the lighting condition as well as the other factors. You will still have access to ISO sensitivity, white balance, exposure compensation, flash firing, flash intensity, & light metering in aperture priority mode.

Aperture priority mode is useful when shooting landscapes. When shooting a landscape, you normally want the entire frame to be equally focused; this can be done by stepping down to your lowest possible aperture opening [f-11 or f-16] as the light condition permits. Remember that these aperture values correspond to narrow lens opening so expect the camera to use a relatively slow shutter speed

Aperture priority mode is also ideal for shooting portraits. Unless you’re eccentric, you want your subject in a portrait sharp & the background blurred out to put heavier emphasis on your subject. This can be achieved by stepping up to your highest possible aperture opening [f-1.8 or f-2.8] as the light condition permits. Remember that these aperture values correspond to wide lens opening so expect the camera to use a relatively fast shutter speed.

There are many other photographic applications in which aperture priority is ideal but the 2 examples above should be enough to give you a sense of when to open wide & when to narrow down your lens opening.

There are cases where a certain aperture value cannot be used.

1. Very large aperture [wide lens opening] may cause overexposure on a bright sunny day.

2. Very small aperture [narrow lens opening] may cause underexposure on a dark night shot.

In these cases, you will be forced to step your selection up or down. Or if you don’t want to, alter the other available controls available to you [as mentioned above]

Shutter Priority Mode

In the Shutter Priority mode, you select the shutter speed & the camera determines the aperture value for proper exposure when you press the shutter halfway. The camera’s selection of aperture value is affected by the lighting condition as well as the other factors. You will still have access to ISO sensitivity, white balance, exposure compensation, flash firing, flash intensity, & light metering in the shutter priority mode.

Shutter priority mode is useful when shooting midnight skylines. When shooting a midnight skyline, you don’t want to use flash [as what point-&-shooters would normally do]. How then can a visible image taken on a dark midnight without the extra source of light? The answer is simple, in the shutter priority mode, use a very slow [or very long] shutter speed [but not necessarily the slowest] to let your lens receive light longer. Let the camera choose the aperture value. Voila! The result is a properly exposed visible midnight skyline. The camera mustn’t move from the time the shutter opens until it shuts. This usually takes at least 10 seconds [or longer] so be sure to carry a tripod along with you or your trip to Kerry Park at 1 in the morning for a potential downtown Seattle skyline will end up to a Starbucks coffee-drinking session.

Shutter priority is also the go-to mode when it comes to sporting events or any situation where you want to freeze a moment [I’ve mentioned this above]. Let’s take a diving competition as an example. If you want a sharp photograph of the diver in action [while on air] a relatively fast shutter speed will do the job. The faster the shutter speed selected the more static the diver will look like in the picture. You may also wish to use a slow shutter speed to show motion [an artistic approach]. A tripod is not needed for fast shutter speed.

Just as with the Aperture priority mode, there are several cases in which a certain shutter speed is not permitted.

1. If the shutter is too fast, underexposure may still happen [even with the widest aperture opening] on a lowlight indoor event.

2. If the shutter is too slow, overexposure is likely to happen [even with the narrowest aperture opening] on a bright outdoor event.

In these cases, you will be forced to speed your selection up or down. Or if you don’t want to, alter the other available controls available to you [as mentioned above]

Semi-automatic mode is what most amateur [or even professional] photography enthusiasts most of the time.

Full Manual Control mode

In the full manual control mode, you select both the aperture value & shutter speed along with the other exposure parameters:

ISO sensitivity, white balance, exposure compensation, flash firing, flash intensity, & light metering

This is the most functional & versatile of all recording modes. You can record any image you can using auto, aperture priority, & shutter priority modes plus other special effects beyond the limits of the above-mentioned modes. Think of this mode as the integration of aperture & shutter priority modes. That is what it really is!

Just as with most technological marvel we enjoy today, the more sophisticated it functions, the more know-how is requires. That’s just the way life goes. If you want a bountiful harvest, you must persevere for it. On that note, I’d like to infer that this is the most challenging mode to record with. Don’t be discouraged. Unlike in engineering [I am an electrical engineering major] in which trial & errors outside the Laboratory are bound to disastrous calamity, fatality is not commonly associated with improperly exposed photographs.

I would love to conclude in an encouraging note:

Mastery is not something that strikes in an instant. Constant practice makes perfect! At the end of the day, you’ll realize that indeed the view from the clouds is well worth the climb.