Exposure

Getting Exposure Right
        (Or putting it all together, Aperture, Shutter Speed and ISO = Perfect Exposure)

Proper exposure means keeping detail (not focus) throughout the image, very little or no clipped shadows, and very little or no blown or hot highlights. (I say very little clipping as a qualifier, in certain instances, small amounts of clipping do not damage the over all look of the image, you would have to evaluate your image to determine if the levels of clipping are acceptable.). The measuring and balancing of light is what exposure is all about. (Note: While someone else’s settings may be useful in guiding you toward capturing your perfect image, chances are copying their exact settings will not give you the same results and lead to disappointment. Lighting conditions are constantly changing and yours may not be the same as the photographer’s in the image you are trying to replicate.)

A few Basic Definitions:
ISO: ISO, in digital photography, is the sensitivity of the camera’s sensor. Higher ISO settings result in noise. (Grainy look) In film photography, ISO in film photography is the sensitivity of the film itself and it is the film or sensor that determines how much light will be absorbed.
Shutter Speed: The shutter speed is how long a shutter will remain open and determines how long a certain amount of light will reach the sensor.
Aperture Settings: The lens aperture is the size of the opening of the lens and controls how much light per unit of time reaches the film/sensor.
Metering: Measuring the amount of light in a particular scene. Most digital cameras offer several types of metering, Center Weighted (large area), Matrix or Partial (Med sized area) or Spot (small section in the focal area). You can use metering to check camera exposure settings and if the image is too light or too dark you will have a starting point for adjusting your settings. (More info on the types of metering available on most cameras Metering Information) Most film cameras do not have a light meter, however, photographers of this medium usually use a light meter to reach correct exposure settings.

How do you determine which settings to start with?
It depends entirely on the type of scene or object you are photographing and the amount of light available as to which of the three exposure variables will be most important to you. (Personally, I choose basic settings based on my previous experiences in a particular situation and take a test shot and check the camera’s histogram, then adjust the settings accordingly.) For instance, in action/sports shots, shutter speed is more important because you’ll want to freeze the action in most cases, or show some sort of movement in the image, in macro or portrait shots the aperture setting is more important because you’ll create a nice Bokeh or blurred background, keeping distractions from your main point of focus to a minimum. In Landscape photography, ISO and aperture may be more important because you’ll want the least amount of noise in the image and the most amount of the scene in focus.

See the light, study the scene, determine where the light is coming from, and is it harsh, usually noonday sun or soft, usually early morning or early evening? Is it overcast and dull or partly cloudy with a few streaks of sun? Are there deep shadows or none at all or soft shadows? Is the light behind you, in front of you or off to the side? In some cases you may want to use a lens hood which will help with possible lens flare. In high contrast scenes you may want to take multiple shots at different exposures or use filters. One thing I do recommend is to never point the lens directly at the sun, you can damage not only your camera’s sensor but also your eyes.

Here are a few basic settings you can start with and then adjust for the unique lighting conditions of the scene you are shooting:

Bright Sunny conditions or the Sunny 16 Rule:
Set the aperture to f/16, if your ISO setting is 100, set your shutter speed to 1/100s. If using a higher ISO, change the shutter speed to match in fractions the ISO Speed, i.e., ISO 200 = shutter speed of 1/200s, ISO 400 = 1/400s, you get the idea. This is good for landscape and cityscape scenes on a sunny day.

Cloudy, Overcast or Shady conditions:
Follow the Sunny 16 rule with the exception of aperture settings, use an aperture of f/5.6.(Remember, changing the aperture settings causes the DOF to change) or slow your shutter by 1 or 2 stops to increase the amount of light coming into the camera’s image sensor.

The Golden Hour:
The first and last hour of sunlight on any given day, give or take a ½ hour or so. This is considered to be, by many, the ultimate time to shoot, reducing the chance of overexposure because the sun is less intense. Typically it will give the objects you are photographing a rich, soft, more diffused glow and will enhance the colors of the scene. Use an aperture of f/1.4 or f/2.8; this will give acceptable results for about 15 min before sunrise and 15 min after sunrise. You may need to use a tripod if using slower shutter speeds or increase your ISO to around 800 or both depending on the amount of light available. (This also works for overcast days).

Fireworks and Lightning:
Use a tripod! Use the self timer or a remote to avoid camera shake. You will not be able to capture fireworks or lightning well without one. Use an 8 second or slower shutter speed, ISO 100 and an aperture setting of f/8 to start with, and then adjust as necessary. (Adjustments could include exposure compensation, whereby you change the exposure to -1, -2 or better). In the case of lightning, start with at least a 10 second shutter speed setting and an aperture of f/5.6, however, is no guarantee that you will catch a strike in those 10, seconds, so you will most likely have to take a number of shots to get the one you want. For those interested in lightning photography, there is an item called a Lightning Trigger, a sensitive optical flash sensor which responds to lightning flashes. It attaches directly onto the camera shoe flash.

Traffic Streaks:
To get those cool looking nighttime traffic streaks, again, a tripod is a must, start with an ISO of 100, aperture setting of f/11 or better and a shutter speed of 8 seconds or slower. You can use shutter priority mode for this, just set the shutter speed and let the camera do the rest. (You may have to use exposure compensation to further adjust for the increased amount of light entering the camera through the use of slower shutter speeds.)

Not an excellent example, but you get the idea. I used Shutter Speed Priority for this, Nikon D700 with a Tokina, 11-18mm @ 18mm, ISO 100, f/22 @ 30s and a -3 stops on the exposure compensation dial. (I used exposure compensation, a low ISO and a small aperture setting of f/22, to offset the enormous amount of light coming into to camera from the slow shutter speed used.)

Light Trails-Atlanta, Ga

Silky Waterfalls, Rivers, Streams and Creeks:
This type of shot is a matter of preference, some people like seeing a smooth, silky looking waterfall or stream and others don’t. Use a tripod, try a ½ second shutter speed and a low ISO setting of 100 (lower if your camera will allow it). As with traffic streaks you can use shutter priority and allow the camera to adjust the aperture setting. You may find this type of photography works better with the use of a Neutral Density Filter, which lessens the amount of light entering the camera allow for longer exposure times without chancing overexposure, however it can be accomplished without a filter. This filter is available in different configurations, allowing you to reduce the amount of light entering the camera anywhere from 2 stops to 9 stops. (In some instances, if your camera has image stabilization or vibration reduction technology, you may be able to achieve this effect to a minor degree without a tripod, see the second image below).

F/11 @ 1/2s ISO 100 70-300 @ 110mm and a Singh Ray Neutral Density Filter set at about 6 stops, tripod.

Silky Looking Water

(Note the very overexposed area in the upper right-hand corner, this is snow and due to the long exposure setting is considered to have blown highlights. My remedy for this type of situation would have been to move to an area where I could get a shot of the stream without the snow in the image. Or select a time of day when the sun wasn’t as bright. Unfortunately, this wasn’t possible at the time. HDR might have been an option, however, the movement of the water may have blurred the final image.

f/32 @ 1/80s, ISO 100, Nikon 70-300 VR(Vibration Reduction was on) @ 70mm, handheld

Manmade Waterfall-Omaha Zoo

Portraits and Macros:
Generally you will want to use Aperture priority for these types of photography, start with aperture settings of f/2.8 to insure the background is nicely out of focus and an ISO of 100, and then allow the camera to choose the shutter speed. Or select a shutter speed of at least 1/60th of a second for handheld shots, do a test shot, then adjust this setting accordingly. On bright days, you should be able to shoot handheld. During overcast days or low light times, use a tripod. Keep the sun at your back if you can when shooting or to the right or left (use a lens hood), watch for background distractions such as a telephone pole sprouting out of the head of your subject.

Landscapes and Cityscapes:
More times than not, as with Portraits and Macro photography, depth of field will be the determining factor in choosing your settings. However, the settings will most likely be the opposite of what you would use under macro or portrait photography. Generally in landscape photography you’ll want more depth to the shot, more of it in focus so you would use a aperture priority setting of at least f/11, ISO 100 and depending on whether there is movement or not (I do a lot of drive-by shootings, taking shots while I’m in a moving vehicle, because it is not expedient for me to stop), I’d recommend a shutter speed of 1/125th of a second if you need to use full manual mode.

Sunsets:
Use a tripod. Be patient, some of the most spectacular sunsets happen after the sun goes down, when the clouds are alit with fire across the skies from the sun’s dying rays of light. Find a good foreground subject. Don’t follow the rule of thirds, because most likely the foreground will be in silhouette and you don’t want a third of your shot black or dark. Don’t aim directly at the sun, it can damage your camera sensor and/or cause overexposure, instead aim slightly above (best position) or to the right or left of the sun. Or use an object in the foreground to partially block the sun. As with landscapes, you’ll most likely want the entire scene to be in focus so you will want to use aperture priority of say f/11 or better which will result in slower shutter speeds because of the lighting conditions, less light, slower shutter. You could increase the ISO for some compensation, but with the light low you will probably experience unacceptable ranges of noise in the image, so the best bet is to use a tripod and a slower shutter speed.

Sunrises:
Sunrises and Sunsets=the golden hour. Use a Tripod. Select Shutter Speed Priority and try starting with a relatively fast shutter speed, 1/1000 or 1/500 and let the camera select the aperture settings and try an ISO to start with of around 400 (You can lower this setting as the sun rises higher in the sky). Then one stop at a time, lower your shutter speed, this should give you a few good shots with good exposure.

High Contrast Scenes:
This can be a tricky exposure. If you exposure for the highlights you will likely throw the rest of the image into darkness or silhouette. If you expose for the mid-tones or shadow areas you risk blowing the highlights. This is very evident in landscapes where the foreground is lush and rich in color but the sky is washed out and almost all white. If shooting landscapes, recommended start settings would be aperture priority of f/8 or f/11 with a shutter speed of 1/125, ISO 100, check your shot and/or histogram to look for problem areas, then adjust the shutter speed slower by one stop at a time to let more light in or by one stop faster at a time to reduce the amount of light hitting the sensor and check the image after each change to see if the exposure is more acceptable. You can choose to take more than one shot of the same scene changing the exposure, one overexposed shot to capture the details in the shadows, one mid level exposed shot to capture the details in the midtones and one underexposed shot to capture the details in the highlights (+1, 0, -1), you would later merge the three images to get one all around properly exposed shot of the scene you were photographing. This is known as Bracketing. You can also use filters to help reduce the contrast, Graduated Neutral Density filters will darken just the sky and circular polarizing filters, (not just a simple polarizing filter as circular polarizing filters are specifically designed for digital cameras) will enhance the blue in the sky. (If you decide to purchase some filters, here’s a tip to save some cash, purchase a filter which will fit the lens with the largest diameter filter sizing that you own or intend to purchase, i.e., 77mm, then buy some step-up rings or adapters for the other lenses, say a 62mm to 77mm step-up ring Cost of the step-up rings are usually under $10 US each. And I’ve never had a problem with vignetting when using adapters.. Buy a slim mount filter if you have wide angle lenses as a regular filter will vignette.) Here’s a quick tip for shooting dark animals, such as Gorillas or Chimpanzees, in high contrast scenes at the zoo, expose for the highlights or lighter areas, set your exposure compensation to a -1 or -2 and take the shot. I know the natural thing to do would be to increase the exposure, but this might actually result in loss of detail or contrast in the dark areas of the animal’s coat.

Reds, Yellows, Whites:
All of these come with their own unique areas of difficulty. It is very easy to clip whites (also called hot areas or blown areas) For whites, meter and expose for the highlights or take several shots if the foreground is still too dark, combine them in a graphics program. If reds are too saturated they begin to look tired and dull. Yellows will loose their definition when underexposed or overexposed. For reds and yellows, expose for the lightest areas of color, you may want to take multiple exposures in this instance also.

F/11 @ 1/500s, ISO 250, D700, 105 micro lens

White Rose

This shot was taken in the late afternoon, sunlight, no clouds, but at the golden hour, right before sunset. A little fill light would have helped soften the shadows in this shot.

F/11 @ 1/60s, ISO 250, D700, Nikon 105 micro lens

Yellow Roses

Also taken late afternoon, sunlight, no clouds, but at the golden hour, right before sunset.

F/3.5 @ 1/800s, ISO 100, D700, Nikon 105 micro lens

Red Rose

This one was taken in the early morning, about 10am, bright sunlight, but the surrounding vegetation shielded the rose. I did use an aperture setting of f/3.5 to soften the image. This also causes the less of the image to be in focus. You can compare the first two Rose images shot at f/11 and the Red Rose shot at f/3.5 to see a visible difference in how much of the image remains in focus at different apertures.

HDR or High Dynamic Range: (I’m throwing this one in just because it can be fun to play with)
This is a relatively new technique which involves multiple exposures, also called Bracketing and allows for more range between light and dark areas of a scene. Then combining all the images and adjusting the contrast and saturation, etc., in a software program (Photomatrix or Photoshop and others) to create more luminous images. Use a tripod for this and a remote shutter release or the self timer on the camera, any movement will result in a blurred final image. For this particular type of photography, you would use aperture priority, because you want the image to be at the same DOF for all exposures. (This does not work well for Landscape shots on a windy day with swiftly moving clouds because this also causes blurring in the clouds) Set your aperture according what you’ve determined is the best for the scene or object, (i.e., landscapes f/11 or better, macros, f/2.8, etc), change the exposure via the exposure compensation, if your camera offers this feature, overexposure 1 or 2 shots by a measure of 1 stop each and do the same with underexposing the scene by 1 or 2 shots at -1 stop and one properly exposed shot. You will end up with 3 to 5 shots of the same scene at the following exposures +2, +1, 0, -1, -2. (More information on HDR Imaging:http://backingwinds.blogspot.com/200…dr-images.html)

11-18 mm @ 18mm ISO 200, Auto WB, f/5.6 @ 1/30, Five shots using exposure bracketing, +2, +1, 0, -1, -2, combined in Photomatrix with tone mapping.(I also use HDR Efex from Nik Software)

HDR-Atlanta, Ga

Notice the sky in this HDR image, the colors from the setting help to dramatize the image in HDR.

With passive photography or natural lighting situations, using different combinations of ISO, shutter and f-stop settings result in an exact brightness or correct exposure. These combinations can drastically affect the final image. Change any one of these three settings and you will have to compensate by changing one of the other settings to keep the same exposure. In other words, if you increase the shutter speed, you will decrease the amount of light coming into the camera, to compensate, increase the ISO or widen the aperture setting. There are drawbacks or trade-offs to this, increasing the ISO increases noise levels and widening the aperture settings creates a shallower depth of field or a more blurred background, which of these changes is more acceptable to your vision of the final image is for you to decide. In cases where you need to keep the aperture settings at say an f/11(lets in less light) or better and changing the ISO settings would result in unacceptable noise levels, you may need to use a tripod to keep from getting camera shake when changing the shutter speed settings (you would need to slow the shutter speed to let in more light) in order to maintain the same exposure.

Take a stop, Give a stop:
Since aperture, ISO and shutter speeds are all measured in stops, balancing them is very easy. Let’s say you’ve got a good exposure but need a different aperture to change your DOF and you are using the following settings:
ISO 100, aperture of f/4 and a shutter speed of 1/250th:
If you take away 2 stops from the aperture, (change from an f-stop of f/4 [more light] to an f-stop of f/8 [less light]) you can give 2 stops back with the shutter (change from a shutter speed of 1/250th [less light] to a shutter speed of 1/60th [more light]) leaving the ISO at 100 or give1 stop back with ISO (change from ISO 100 to ISO 200) and 1 stop back with shutter speed (change from a shutter speed of 1/250th to a shutter speed of 1/125th)
Your new settings would be:
ISO 100, Aperture f/8, Shutter Speed 1/60th (please note, that at this shutter speed, you will most likely require a tripod)

Or you can give back 2 stops through the ISO settings (change ISO from 100 to 400) leaving the shutter speed at 1/250th and this will still keep the original exposure intact.
The same principles would apply if you needed a faster shutter speed, you would increase the shutter speed and change aperture and ISO or ISO alone or Aperture alone. Just remember however many stops you decrease or increase one setting by, you must adjust one or both of the other settings by the same amount, 1=1 and 2=2 and so on and so forth.

Histograms:
This is the histogram of a correctly exposed image:

Histogram

If there is a major shift of the big black area to the right of the histogram or spikes where the arrow points upwards, look for overexposed white or light areas in your image. If the shift is to the left, where the arrow and the word black are, look for lost details in the darker portions of the image. (Some cameras have an alert/setting, which will blink in the areas that are over or under exposed when reviewing the image). While you might, with software, be able to bring back some of the darker areas, this usually results in excessive areas of noise, thus leaving the image unusable in most instances. As for the opposite, blown or clipped white areas, usually it is near impossible to save the image and regain the lost information needed to produce an acceptable image. Please bear in mind that at times you may have some minor or small areas of clipping in either direction, determine if this detracts from the image or is acceptable in the overall scheme of things. Most often these minor areas of clipping will occur in extreme contrast shooting situations, such as extremely bright skies and darker foregrounds or sunset shots.

Noise Levels:
At low ISO settings such as 100, 200 or 400 noise levels should be acceptable. However, at ISO settings of 800, 1600, 3200 or 6400, noise levels will deteriorate and you will be left with image that is not all that acceptable. This occurs a lot with Night Photography. I’d recommend using a tripod with lower ISO settings and longer shutter speeds to compensate for the lack of light you’d get with an ISO of 100 or 200 or 400.

Aperture f/4.5 @ Shutter Speed 1/6, ISO 6400

Candlestick Point

Candlestick Park at Night, as you can see the higher ISO setting resulted in unacceptable noise levels.

The WOW Factor
What is it? It’s the aspect within an image that makes people say WOW, that’s stunning or amazing.
I want it, how do I get it? Yes, more rules.
Selective Focus: If you can’t move in to get a better focal point and you can’t move the object, use an aperture setting which will give you a nicely out of focus background.
Play with the placement: In other words, don’t center the object unless doing so makes the image so stunning that breaking the rules pulls the WOW from viewers.
Keep it Simple: Simple always takes center stage in an image, if there is nothing but your focus point to center on, then it can lead to a WOW.
Move Closer to the Subject: This brings prominence and focus to the subject you are photography and keeps it simple.
No Busy Backgrounds: This will tend to pull the eye from your focal point, so again simple or blurred is better.
Unusual Angles: Lie down and look up, kneel, look down from your window, etc. The element of surprise is a wonderful way to grab a viewer’s attention.
Vary your Orientation: Use portrait orientation instead of landscape or shoot both and decide later which works best.
A Sense of Depth: Use your surroundings to create a sense of depth, leading lines, roads, trees, telephone poles, anything that will pull the viewer deeper into the image.
A Sense of Size: Find something small to place next to the large object you are photographing, example: a person next to a redwood.
A Sense of Balance: Balance your light and dark areas or weaker and stronger objects so that one doesn’t overpower the other.

D300, Nikon 105 micro lens

Giant Waxy Monkey Frog

All the elements of a good shot, it’s simple, has beautiful Bokeh, good DOF, background colors enhance the focal subject, composition is good and it’s sharp and clear.

Go out and take some pictures….be aware of your surroundings….watch the light, check the view finder, most of all, have fun!

Mary Robinson