The Bermuda Triangle: Aperture, Shutter Speed, ISO

I call these three concepts the Bermuda Triangle because this is where a lot of photographers get lost. Together, the aperture, shutter speed and ISO triangle determines how much light is allowed into the camera. ISO controls how sensitive the sensor is to that light. Understanding the interplay of these three concepts is key to mastering the technical dimension of photography. You can compose an amazing shot in the viewfinder but if these three settings aren't right you'll be the only one to ever see it.

The flow of light is hard to visualize, so let's try water. Think about spraying water on a sponge with a hose. The hose is the lens. The sponge is the sensor.

The diameter of the hose is equivalent to aperture. A fire hose lets more water through than a garden hose and a 6.3 aperture lets more light in than an 11. No, that's not a typo. Higher numbers mean less light. The lower the number the wider the lens opening. Lower numbers are the fire hose, higher numbers the garden hose. This can be counter intuitive so just memorize the rule.

How long the hose is turned on is equivalent to shutter speed. The longer you open the hose, the more water flows through. The longer the lens opens up, the more light comes through.

Shutter speed and aperture together determine how much light comes in through the lens to the sensor. The most important concept to understand to truly master shutter speed and aperture is to understand how different combinations actually let in exactly the same amount of light. A garden hose left on for a long time can pour out as much water as a fire hose left on for a short time.

An f/5.6 aperture at a 1/60 second shutter speed lets in exactly the same amount of light as an f/8 at 1/30. 1/30th of a second is twice as long as 1/60th of a second, but an f/8 lets half as much light in as an f/5.6. Half the light for twice as long is the same as double the light for half the time.

How absorbent the sponge is equates to ISO. Higher numbers mean more absorbent. An ISO 100 needs a lot of water, ISO 1600 not so much. ISO is important when you hit the constraints of what aperture and shutter speed can do in a given situation. In a low light situation at ISO 100 opening the aperture all the way might still require opening the shutter for several seconds to get enough light to properly expose the shot. Chances are you or your subject can't hold still for that long and the picture will be blurry. Bump the ISO to 200, now you can shoot twice as fast. Bump to 400 and twice as fast again.

A note on the lingo - fast lenses and stops.

Different lenses have different maximum aperture openings. Lenses that can open wider than most are often called "fast" lenses because they can open up to let more light in and allow using a faster shutter speed.

f-stop is the unit of measure for the aperture size. The f comes from the use of focal length in the formula that determines the number (see the Wikipedia article if you are interested in the specifics). A "full stop" is a change in aperture that doubles, or halves, the amount of light. Because of how the math works out, a full stop is a multiple of 1.4. An f/5.6 allows twice as much light as an f/8 (f/5.6 X 1.4 = f/8). Similarly, a full stop of shutter speed indicates twice or half the light. In this case multiplication by two is all that is necessary. 1/30th a second lets twice the light through as 1/60th. ISO full stops work the same as shutter speed, ISO 200 is a full stop higher than ISO 100.

In fully automatic modes, the camera figures all this stuff out as best it can. The semi-automatic modes let you take control of one setting then automatically changes the remaining two. Aperture priority and shutter speed priority are the two most common semi-automatic modes. In manual mode the camera leaves it all up to the photographer.

To really get it, put your camera in manual mode. Pick ISO 100 outdoors, 200 if cloudy, 400 indoors, 800 if the lighting is low. Set the aperture to f/8. Now change the shutter speed until the camera exposure meter indicates a correct exposure (in the center for most cameras). Take a picture and look at it. Set the shutter speed to twice as fast to let half the light in, shoot. The photo is darker, underexposed. Open the aperture one full stop to let twice the light in (f/5.6 if you started at a f/8), shoot. The picture should look exactly like the first. Double the ISO to make the sensor twice as sensitive, shoot. The photo is too bright, overexposed. Now either set the shutter speed to twice as fast or close the aperture one stop (from f/5.6 back to f/8).

Get it?

Just when you think you are ready to navigate the triangle, each setting also has artistic consequences. Aperture controls depth of field, shutter speed controls whether motion is frozen or fluid, and ISO influences the noise or graininess in the picture. But those are topics for another day...

Links: 
The Real Bermuda Triangle
The Nerdy Details of Aperture

Holiday Portrait Tips

Cameras are an inevitable presence at holidays and family get togethers. The good news is because people expect cameras to be around and are busy with the festivities you are less conspicuous as a photographer. If they have a few drinks to loosen up, all the better. ;)

The Group Portrait

When time for the group photo does come remember this: scene, squish, faces.

Scene
Look for the right spot before hand. Pick somewhere with enough room for everyone, even lighting and a background that won't distract. Stand back and look through the camera to make sure you can fit the whole scene in the frame. Outdoors is a great choice if you can coax people out in the cold.

Squish
Squish people together. Then turn them a bit sideways and squish even more. If you can't fit everyone in, squish some more and have small children kneel or sit in front.

Avoid people standing at a comfortable distance facing directly at the camera. This creates pictures with American Gothic Syndrome - a fine historical record but otherwise boring.

Faces
Make sure you can see everyone's face. There are lots of different rules about arranging people but for portraits at the holidays don't even try. Just make sure all the faces are visible.

Look around for some group wedding pictures as a reminder of what you're trying to accomplish. Notice how close everyone is and the lack of distraction in the background. Of course, holiday pictures should be more fun and less casual.

Shoot!
Use the widest angle lens you have. Shoot in portrait mode when in automatic or an aperture 6.3 or lower for manual shooting. This will cause the background to be blurred out and keep the focus on the people. This is the best choice the casual indoor shots as well, so set the mode for the day and forget about it.

Don't do the, "Cheese! Wait, wait one more!" bit. Say something like, "Here we go!" then keep talking and shooting until the group loses interest (one minute, tops). Use the low speed continuous shooting mode if the camera has one.

Casual Shots

It's okay to take pictures of just a few people or even one person. These can be some of the most rewarding shots that capture the individuals and happenings as people remember them.

Keep the camera handy. Take pictures when you are least likely to remember to do so, that is, if you can remember. The funny or awkward moments make for the best shots. That is where the essence of the people and the holiday are.

Notice the things that make people recognizable and include them. The uncle with the crazy mustache, the six year old missing two front teeth or the tacky Christmas sweaters grandma wears every year.

Also notice the things that characterize how people interact. Are two brothers always badgering each other? Shot them the next time they chase each other through the kitchen. Are there holiday collaborators? The two cousins who conjure up a secret egg not recipe every year. Shoot them mixing it up.

For kids, get down on their level.

If the lighting is low enough that flash is required dial down the flash exposure compensation (if the camera allows) and place some kind of diffuser over the flash bulb. Tape and toilet paper will do. For more on making the best of built-in flash, see the earlier entry on best and worst equipment.

This Shot

This portrait of my son is from a small Christmas party at a friend's boutique. There was a bowl full of lollipops at a child friendly height. Throughout the night he managed to dig every last blue lollipop out of the bowl. I enjoy this picture because it reflects who he is and what he's up to. The background identifies the holiday setting while the coy look and lollipop give a sense of childish mischief. The perspective is at his level creating a more intimate feel. A touch of serendipity helps. The chance blue color of the lollipop helps it pop (haha!) and stand out, reinforcing the reminder of his mischief.

The Useful Bit: 
For group portraits, remember: scene, squish, faces. For casual shots, keep the camera handy, remember to take pictures when you would most likely forget and look for things that make people, places and happenings recognizable.
Links: 
American Gothic, a good painting but not the best model to follow for the family portrait
Monkee's of Nashville

The First Three Steps - Pick a Subject, Compose, Shoot

After you get those first few good shots photography can make you crazy.

You got a few good pictures, why can't you do it again? Why are most of your pictures still those boring vacation shots that put dinner guests to sleep? If you take enough pictures, sooner or later you'll shot a few that are worth a look. That's luck. If that luck is motivates you to figure out why they were worth a look and how to do something like that again then the photographer in you just hatched and is ready to evolve.

When my son first started walking I always joked it should be called falling. He did more falling than walking. The same is true about photography and can make you nuts. Lots of people give up at this point. When I got stuck here I started reading and talking to people and this is the formula I came up with: pick a subject, compose the take the shot. It got me out of the photo funny farm.

It sounds simple, but think about when you took pictures in the past. Did you look around and explicitly make a decision about what to take a picture of? Did you look at what was in the viewfinder or LCD and decide where to put the subject in the frame? Did you actually press the shutter button and take the shot?

To illustrate how these three steps work look at some of my own failed photos from a trip to Germany and France in December 2003. I won't call them bad. The only bad photos are the ones you don't take.

The first photograph below missed the first step, a subject. There is vaguely a focus on the buildings but there is no dominant subject. Your eyes are left wandering for something to look at. That's one more shot in the boring vacation pile. Look around before you shoot. If something catches your eye, maybe a photo of that something will catch your eye too.

The second photo missed the second step. There is a clear subject. His name is Lesley, a jovial Irish bloke. You find the subject immediately with a curious goofy expression but the interest stops there. There's nothing to explore in the photo. Here are three rules to improve composition that are simple enough to remember in the few seconds there are to put a shot together. Keep the subject out of the center, pay attention to the background and fill the frame. This photo misses on all three counts. The subject is dead center, the background looks to be a junk yard and the top half of the frame is a blown out sky. Finally, Lesley is too far away to get any sense of him as a person. The shirt is more the subject than the face at this distance.

Right behind me was a brownish stone cottage. I should have asked him to stand in front of it. It would have contrasted well with his shirt and complimented his disheveled look. If I moved close in, put his face off center and coaxed him to smile I might have had more success.

All of these failed photos did follow the most important rule - take the shot! Don't be afraid to take pictures like these that fail miserably. Each one is a chance to reflect on and improve your chances of success next time.

Now on to two shots that are more successful. First, the third shot below of a street scene. It's not a great shot, but does hold some interest. Unlike the first photo of a street this has a subject, albeit a composite subject. The overall street scene is the subject not any one actor. The receding lines give you a sense of perspective and bring you into the scene. The dinner guests might still fall asleep but at least get a sense of being there.

The featured shot above is the best of the lot. The location is the central square in Nuremberg, Germany. There were two subjects of interest to me. The cathedral and the McDonalds. The cathedral for the architecture and the McDonald's for the oddity. It was a modern icon plopped down in the middle of a historic square. This shot combines the two subjects through the reflection of the cathedral on the McDonalds window. The advertisement in German adds another hint of context.

The Useful Bit: 
Not sure where to start? Pick a subject, compose, shoot. Keep the subject out of the center, pay attention to the background and fill the frame.