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Shutter Speed

November 18th, 2013

Shutter Speed

Shutter speed is how long your shutter is open to record the image. It is measured in seconds, and generally in fractions of a second. For example, 1/60 means that your shutter is open for 1/60 of a second. 1/1000 would be 1/1000 of a second.

The longer your shutter is open, the more light will reach the sensor, which will result in a brighter image. Conversely, the less time your shutter is open, the less light will reach your sensor and you will have a darker image. 1/1000 would be a fast shutter speed and would therefore let in less light than 1/60.

In bright light, you use a faster shutter speed so that you donít overexpose your image. In low light, you use a slower shutter speed so that you donít underexpose.

Shutter speed also determines how motion is portrayed. A fast shutter speed will freeze motion, and a slow shutter speed will show motion as blur.

You want to make sure you use a shutter speed that is fast enough to avoid camera shake from handholding and fast enough to stop subject movement.

A good rule of thumb to avoid camera shake is to keep your shutter speed at least 2 times your focal length. So if youíre shooting with a 50mm lens, youíll want a shutter speed of at least 1/100. But if youíre shooting with a 200mm lens, your shutter speed should not drop below 1/400.

Also, everybody hits a point where they can no longer handhold, no matter how wide of a lens theyíre using. For most people, this will be around 1/60 to 1/100.

Some people are steadier than others and can get away with slower shutter speeds. Some are less steady and will need even faster. The best thing you can do is to experiment and find out how slow you can handhold and consistently get shake free images.

And then, depending on what youíre shooting, you may need an even faster shutter speed to stop subject movement than you need to handhold.

If youíre shooting a wiggly toddler, youíll want a shutter speed of at least 1/250. But if youíre shooting wildlife or sports or other fast action, youíll need a shutter speed more along the lines of 1/500 to 1/1000 or more.

If you want to purposely show blur, like a waterfall with that smooth, foggy look, youíll need a very slow shutter speed. Those shutter speeds can measure around 1/2 of a second to several seconds long. A tripod will be necessary to avoid blur from camera shake.

Another helpful thing to keep in mind with shutter speeds is that for every full stop you raise or lower your shutter speed, youíre letting in exactly half or twice as much light as the previous stop.

For example, 1/125 lets in twice as much light as 1/250, which lets in twice as much light as 1/500, which lets in twice as much light as 1/1000 and so on.

On most cameras you will be able to adjust your shutter speed in 1/3 stop increments.

You will see how this is helpful to know when you learn about aperture, ISO and the exposure triangle.


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November 18th, 2013


The aperture of the lens is the opening of the lens that lets light in to record on your sensor. This hole can be made larger or smaller to let more or less light in. Itís similar to the pupil of your eye in that a larger opening will let in more light than a smaller opening.

The different apertures you can use are called your f/stops. It seems a little backwards at first, but a larger number (such as f/16) is a smaller aperture and lets in less light than a larger aperture with a smaller number (such as f/4).

Larger apertures are needed in lower light or otherwise youíll end up with underexposed pictures.

Like your shutter speed, each full stop will let in exactly twice or half as much light as the previous stop. And also like your shutter speed, your lens will probably let you adjust your aperture in 1/3 stop increments. Your lens will determine the maximum and minimum apertures you can use.

Besides how much light is allowed to enter your camera, aperture also affects something called Depth of Field. Depth of Field (DoF) is the area of your photo that is in acceptable sharpness. A large DoF will have a large area that is in focus. A small, or shallow, DoF will have a small area that is in focus.

A large DoF is nice when you want a large part of your picture to be in focus. In a landscape for example, you might want everything from the flower right in front of you to the mountains in the distance to all be in focus.

A small DoF is nice when you want to isolate your subject. A small DoF is oftentimes used with portraits to really make the subject stand out from the background.

A larger aperture (remember, a smaller number) will give you a smaller DoF than a smaller aperture. Portraits may be shot in ranges like f/2 to f/4, whereas landscapes may be shot at f/16 to f/22 or so.

There are two other factors that affect DoF; focal length and distance to subject. But that's for another post.


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November 18th, 2013


ISO is how sensitive your sensor is to light. In bright conditions, your sensor doesnít need to be very sensitive. But in low light situations, you need to make your sensor more sensitive to light.

Lower ISO numbers are less sensitive to light than higher ISO numbers. Outdoors in bright light, you may use an ISO of 100 or 200. In deep shade perhaps an ISO of 400. Indoors, youíll probably need an ISO of at least 800 to 1600 and higher would not be unusual.

The trade-off with using a higher ISO is that you get more digital noise, or grain. However, itís better to have noise than motion blur from using too slow of a shutter speed or out of focus areas because your DoF is too small. You can minimize noise with noise reducing software, but you canít do anything to fix blur or out of focus images.

You will also get more noise if you underexpose your image and try to raise your exposure in post processing. For example, if you shoot a scene at ISO 200 but underexpose it, you will get more noise than if you had used an ISO of 400 and gotten a proper exposure in the first place.

Like shutter speed and aperture, your ISO is measured in full stops that double or halve how sensitive your sensor is to light. ISO 800 is twice as sensitive to light as ISO 400, which is twice as sensitive as ISO 200 and so on.


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The exposure triangle

November 18th, 2013

The exposure triangle

Now that you understand shutter speed, aperture and ISO, itís time to find out how they all work together to give you a proper exposure.

When you shoot in any of the auto modes, your camera chooses average settings. It doesnít know if what youíre shooting is moving or stationary. It doesnít know if you want a large or small Depth of Field. The camera doesnít know if youíre shooting a polar bear in a snow bank or a black dog in a coal mine. So it just chooses average, middle of the road settings. If itís an average scene, your pictures will probably come out okay.

But what if itís not an average scene?

When you shoot in Manual mode, you choose the shutter speed, aperture and ISO to give you the exposure and look you want. You know if youíre shooting something that is moving extremely fast and so you know to select a fast shutter speed. Or, you want a very shallow DoF, so you choose a large aperture. Or maybe you want a dark and moody picture, so you purposely want to underexpose your image. You know what you want your pictures to look like, your camera doesnít.

Say youíre shooting something that is moving very fast and you want to freeze the motion. You know you need to select a fast shutter speed for that. But remember, that fast shutter speed will not allow a lot of light to reach the sensor. So you compensate for that by using a larger aperture and/or by using a higher ISO.

Or, if youíre outside in bright light and youíre using a large aperture because you want a very shallow DoF. You donít want to overexpose your picture by letting too much light in, so you use a faster shutter speed and/or use a lower ISO.

If at any time youíre shooting and your pictures look underexposed (too dark) you can either open up your aperture, slow down your shutter speed and/or raise your ISO. If theyíre too bright, do the opposite, stop down your aperture, raise your shutter speed and or lower your ISO.

Remember how you learned that each full stop of aperture and shutter speed lets in exactly half or twice as much light as the previous or next stop? And that each stop on the ISO chart was exactly twice or half as sensitive as the previous or next stop?

Well, this is handy to know because now you can realize that settings of f/16, 1/100, and ISO 100 will give you the exact same exposure as settings of f/8, 1/400 and ISO 100, as will many other combinations. If youíre happy with your exposure and just want to change your shutter speed or aperture to get a different look, you just have to remember to adjust one of the other two settings the same number of stops to keep the exposure the same.


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Why you should not chase the meter

November 18th, 2013

Why you should not chase the meter

This is a good experiment to show why, when shooting in Manual mode, the point is not to just line the meter up under the 0.

I think this can be an eye opening experiment for some. All you need is your camera, a white sheet of paper & a black sheet of paper. (or a white wall or black wall, something). If you have a gray card, use it too. If you don't have a gray card, still do this experiment. Just skip the step with the gray card. You will still see a big difference.

1st step is to set you camera to Manual mode.
2nd step, prop your gray card up somewhere. (if you have one, use the white sheet of paper if you don't)
3rd. Fill your frame with the gray card. Meter until it reads 0. Note your settings. You don't have to take a picture, just note what your camera thinks is the correct exposure.
Next, take down the gray card & place the black piece of paper in the same place. Now, making sure you're in the same spot too, fill the frame with the black paper & look at your meter. Your meter will no longer be under the 0. Change just one of your settings until your meter is back under the 0. Note your settings.
Now, do the same thing with the white piece of paper. Again, notice that your meter will no longer be under the 0. You will have to change one of your settings to get it back under the 0. Note your settings again.

What happened? The light didn't change, so why did your meter? It's because your meter is always trying to expose everything to 18% gray. It didn't realize that what you were metering off of was white, black or gray. It was just trying to give you a correct exposure for 18% gray. Not for a white sheet of paper. Not for a black sheet of paper. Only 18%. So if you had actually taken a picture after you changed your settings to line it up under the 0, what would have happened? If you had a gray card, that one would have been exposed correctly. But the white paper would have been underexposed & the black sheet would have been overexposed. If you had taken the shots, both of those would have looked more gray than black or white. But if you shot these same scenes using the settings that were correct for 18% gray, then all of your pictures would have been properly exposed. Even though the meter would have said otherwise.

So this tells you that once you have your settings how you want them, don't change your settings unless the light changes. Ignore the meter at this point. If you move your camera to include something that is lighter or darker, your meter is going to move. But the light hasn't changed. Your meter thinks you need to change your settings, but you know better. You've already got the exposure you want. It doesn't matter if you're pointing your camera at something white or black or gray.

So that's why I prefer to shoot in Manual. Once I have my settings how I want them, I don't change them unless the light changes or I want to change my DOF or something. Light is a lot more constant than most people realize.

And my shots are going to be very consistent exposure wise. If I were shooting in one of the semi automatic modes, my exposure would be all over the place. As soon as something dark comes into the scene, my camera is going to think it needs to change the exposure. Same thing if something bright pops up. So every time I take a picture, my exposure will be different because my camera kept trying to meter everything for 18% gray. But not if I'm in Manual & not chasing the 0. They're going to look the same from picture to picture, no matter what I'm photographing, because the light didn't change.

Here are some examples:

1st, I metered off a gray card & 0 on the meter was ISO 200, f/5.6 and 1/20.

Gray card picture

 photo IMG_6003_edited-1.jpg

Kept the settings the same, but I changed to a white background. Meter was showing 1 full stop over the 0.

 photo IMG_6004_edited-1.jpg

Now I changed to a black background. Settings are still the same. Meter now reads 1 2/3 stop under 0

 photo IMG_6005_edited-1.jpg

You'll notice that the exposure of the kitty is fairly consistent. And that the white paper is mostly white & the black paper is mostly black.

Now these next 2 pictures were taken while lining the meter up under the 0. What the camera thinks should be the correct exposure.

Black sheet of paper. I kept the ISO & aperture the same. ISO 200, f/5.6 but to get the meter under the 0, I changed the shutter speed to 1/8.

 photo IMG_6006_edited-1.jpg

White sheet of paper background. Again, ISO & aperture are the same, but to line up under the 0, the camera suggested a shutter speed of 1/60.

 photo IMG_6007_edited-1.jpg

Notice the big difference in the exposure in the above 2 pictures. The backgrounds aren't nearly as white or black as they should be. And look how overexposed the kitty is in the 1st picture & underexposed in the 2nd picture.

And then, just for fun, aperture priority. Again, kept ISO & aperture the same. ISO 200, f/5.6.

Gray card, the camera chose 1/13.

 photo IMG_6009_edited-1.jpg

White background, camera chose 1/50

 photo IMG_6008_edited-1.jpg

Black background, camera chose 1/5

 photo IMG_6010_edited-1.jpg

Notice how the exposure is completely different in these 3, even though the light didn't change. Just a different background.

And that is why I shoot in Manual mode & don't just try & line the needle up under the 0.


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Depth of Field

September 25th, 2013

Depth of Field

Depth of Field is the area of a photograph that is in acceptable sharpness. A large DoF will have a large area of the photo that is in focus, whereas a small, or shallow, DoF will have a small area in focus.

A small DoF is used when you want to isolate your subject from the background. It can be useful for things like portraits, to really make your subject stand out, or to blur an unappealing background.

A large DoF is often used for landscapes, so that everything from the foreground to the background will be in focus.

Three things determine how much DoF a photo will have; your aperture, your focal length and your distance to subject. Most people learn early on that aperture plays a role in DoF, but are oftentimes surprised to realize that focal length and distance to subject are just as important.

If you want a small DoF, use a large aperture (a small f/number, like f/2 instead of f/11), use a longer focal length (like 85mm instead of 35mm), and/or be closer to your subject.

If you want a large DoF, use a small aperture, use a shorter focal length, and/or be farther away from your subject.

And while your subjectís distance from the background isnít one of the things that determine your DoF, the farther away from the background your subject is, the more time it will have to fall out of focus. So even if you use identical settings, a background that is farther away from your subject will be more out of focus than one that is closer to your subject, even though the DoF is the same.


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