Filters: Using a polarizer

The ability to alter images in post-processing of digital photography has eliminated the need for most of the enhancement filters that had been so popular in film photography.  In fact, the digital sensor is so much more sensitive to optical quality that placing any filter -- especially one of poor optical quality -- in the optical path will most likely be detrimental to the quality of the final image.  One filter effect that does not lend itself to complete obsolescence in the digital age is the polarizer -- although one of the more common uses of the polarizer, darkening blue skies, can usually be done with simple post-processing.

A popular use of a polarizing filter is to darken a blue sky.  With modern digital photography and post-processing this is not as important a use as it once was.  In the photo above a polarizer was not necessary.  The sky was simply darkened and contrast added afterwards in Photoshop.

What to look for:

Polarizing filters come in two varieties: linear and circular.  On a camera incorporating either AF (auto-focus) or built-in metering -- which is to say all modern DSLR cameras -- use a circular polarizer.  A linear polarizer will disrupt the AF ability of the camera and give false readings to the built-in light meter. 

A polarizing filter must turn to produce its result.  This necessitates a filter mount that may be thicker than an ordinary filter, and can cause vignetting with wide angle lenses.  Better quality polarizing filters are specially made with thinner mounts.  As with any filter used in digital photography, it is best to spend a little extra for a higher grade filter mount, optical glass, and coating of the glass.  This will have the least negative impact on the optical system of the camera.

Darkening blue skies:

A polarizing filter can be used to add punch to a landscape or travel shot by intensifying a blue sky, particularly if there are interesting cloud formations present.  The clouds will stand out more dramatically against the deeper blue.

The photo of the Empire State Building on the left is without a polarizer; that on the right is with.  Notice how the sky is darkened, plus additional color and contrast are added to the building in the polarized image.

 As already mentioned, much of this darkening can also be done in post-processing of the image.  Nonetheless, when you combine the ability of the filter to also add deeper color to other reflective surfaces in your shot, using the polarizer may be a better solution that post-processing.  Keep in mind that a polarizer will only work on a blue sky.  It does nothing for a cloudy sky. The ability of a polarizing filter to darken a sky depends on the type of sky and your shooting angle in relation to the sun.

 

A polarizing filter has its greatest darkening impact on a sky when the section of the sky being photographed is at a 90 degree to the sun, as in the illustration above.  At sunset, with the sun directly behind you at 180 degrees a polarizer will have no effect whatsoever

The polarizer works best when it is used closest to a right angle (90 degrees) from the sun.  With the sun behind you or overhead, turn the polarizer in its mount until you see the darkening effect in the camera viewfinder.  A polarizer can darken the exposure by as much as 2-stops.  Be aware of this and make any necessary exposure adjustments in your cameras, if you are in manual exposure mode.  Your camera meter should be able to compensate for this adjustment automatically.  

This image illustrates two potential problems with adding a polarizer to a wide angle lens.  First, the filter mount was too thick for the 28mm wide angle lens on this full-frame camera.  This resulted in dark, vignetted corners in the image.  Second, the sky varies in darkness from left to right resulting in uneven exposure.    This is amplified more through use of the polarizer.  Here is an instance where no polarizer would have been better.

Using the polarizer in conjunction with a wide angle lens may cause other problems.  The blue sky changes intensity as it moves from the 90 degree angle in relation to the sun.  A polarizer can negatively emphasize this exposure contrast when using very wide angle lenses.  

A second thing to look for with a polarizer on a wide angle lens is vignetting, which is the darkening corners in the image.  This is caused by the lens actually seeing part of the filter mount and recording it as a dark out-of-focus area.  Be aware of these problems.  You may not actually be able to see them occurring through the viewfinder.  When using an extreme wide angle lens, it is best to also take a backup shot without the filter in place.

Restoring color to foliage and other reflective surfaces:

One of the most useful implementations of a polarizing filter is in landscape photography for bringing out the saturated color of foliage.  A polarizer also cuts down the exposure, sometimes by as much as one or two stops.  This can be an aid to photographing moving water where you want to create a blur of the water by using a slow shutter speed.

Without a polarizer to cut the reflections the leaves in the top photo are completely washed out through over-exposure.  In the bottom image the full color and saturation of the leaves is restored by turning the filter to eliminate the unwanted reflections.

A typical example of where a polarizing filter is important.  It was used in conjunction with a neutral density filter to lower the exposure to 1/2 second which added a blur motion to the moving water.  At the same time the polarizer cut out the reflections on the foreground leaves and rock surfaces to result in a deeply saturated photo with plenty of color and detail.

One of the most important reasons to use a polarizer is so you can restore color to reflective surfaces.  This is particularly prevalent when photographing landscapes with foliage.  The surface of leaves are pointed skyward.  Since the leaf surface is glossy, it will reflect the pure light falling on it from the sky.  This will result in loss of color and actual over-exposure of the bright, reflective surface on the leaf.  A polarizer can eliminate this reflection and restore the natural color beneath it.  

This is a dramatic example of how a polarizing filter can eliminate the sky reflections in foliage and bring out the true colors of the leaves and flowers.

Here the polarizer is doing double duty by darkening the blue sky and also bringing out the colors in the autumn leaves.

Eliminating unwanted reflections:

The ability to remove unwanted reflections can be beneficial when photographing any reflective surface, such as glass, metal, water surfaces, or even shiny skin. 

The polarizer works best at a 90 degree angle to what is being reflected.  The photo on the left of a store window reflects the street scene to such a degree that the sign in the window is almost illegible.  On the right the polarizer almost completely eliminates the distracting reflection and now the sign behind the window is clear

Use of the polarizer on the right image eliminated the white sky reflections in the statue and brought out more color in the metal.

The only difference between these two images is that the polarizer was used for the photo on the right.  Color saturation is restored, glare is eliminated.

 The polarizing effect can sometimes be overdone.  It is not always necessary to turn the polarizer to its full effectiveness.  This may eliminate reflections that are integral to the final photo.

In this instance, the polarizing filter totally eliminated the reflection of the sailboat in the water.  Including some degree of the reflection would have made the shot more interesting.

Here the polarizing filter was only partially turned -- just enough to deepen the colors in the water and the shiny skin of the model, but not so much that it eliminated the important reflection of the girl in the sand.

As always, proper use of an aid to photography should enhance the creative outcome of the image, not detract from it.  Know the limitations and abilities of your equipment and accessories.  Sometimes knowing when not to use a piece of equipment is as important as knowing when to use it.

All content copyright 2011, Tom Grill Images, LLC

How to Photograph Fireworks

Obtaining colorful and exciting photographs of firework displays is not difficult, but it does require an ability to work a camera in manual mode with a remote release. Digital cameras have made photographing fireworks much easier and fun to do.  Here is how it is done.

You will need a steady tripod for your camera, a remote release to hold the shutter open, and a lens that will enable you to fill the frame with the fireworks display.   A zoom lens is best because you can modify the cropping as you go by zooming in or out.

Fill the frame with the bursts for the most dramatic effect.  On a dark night you can even leave the camera shutter open to capture several bursts in the same exposure.

 The first thing you need to do is determine where to aim the camera.   Fireworks displays usually go off from a fixed location and cover a limited area of the sky.  You should be able to see the individual fireworks trail as it shoots up from the launch area.  Fix you camera so that it covers the area of the sky where the  full burst occurs.  It is usually best to fill the frame with the burst.  Including too much of the dark sky is dull and uninteresting. 

 

Set your camera to manual exposure mode.  You will need to also set the shutter speed to B, or Bulb, which will keep the shutter open as long as you are holding in the button on the remote release.  Choose a low ISO setting -- preferably the base ISO of your camera.  This will usually be ISO 100 or 200.  Set your camera menu to turn off the noise reduction for long exposures. This will only slow your camera down and is unnecessary where the dark areas are pure black. 

Your lens should also be set to manual mode.  The auto-focus mode may have to hunt for a focus point that will result in many out of focus images.  Note that on most modern auto-focus lenses the actual infinity setting of the lens is often not at the very end of the focus ring range.  You will need to set the infinity symbol on your lens by eye.  Set it for the very center of the symbol.  The focus ring can easily be bumped off of its setting so it is wise to tape the ring securely in place while shooting.

Over-exposing the photo will result in a colorless image, like the one on the right.  Close the aperture down another f/stop or two until you can see some color on your camera display.

The proper selection of lens aperture is a bit of a variable.  Fireworks differ from one another in terms of brightness.  So you will need to do some on the spot testing to determine the best f/stop to use.  The range is usually between f/8 and f/16, but can go as low as f/22.  With an ISO of 100, I would recommend starting with f/8 (f/11 for ISO 200).  Overexposing the fireworks results in washed out bursts lacking in color.  So it is best to keep the exposure toward the darker end and bracket by at least one full f/stop, or even more.  For instance, you could begin with f/8, then try f/11 and f/16.  Check your camera display to see if the color is in the burst. 

To avoid your fireworks photos looking like the bad example above you need to keep your shutter open long enough for the bursts to record in the frame.  When the exposure is too short, the burst does not have enough time to "paint" itself in your picture.  That is why the burst streaks in this photo are so short.  There is also far too much dull, black sky in the photo.  This photo needed to be cropped tighter.

Here the crop was tighter and the shutter was open long enough to capture several bursts of fireworks that allowed them to create long, bright streaks that completely fill the frame.

Timing is very important.  You want to keep the shutter open long enough during the burst so that it "paints" itself on the camera sensor.  This will give you the fullest color. Too short a shutter speed will only record a small part of the burst.  You want to record as much of the burst as you can without over-exposing the photo.  The length of exposure depends upon the brightness of the burst and the sky.  If you have set your camera up properly, you can release the shutter as soon as you see the firework begin its upward motion.  Keep the shutter open during the full burst.  This is usually between three and eight seconds, but could be longer if the sky is really dark.

If your camera can double expose, you might want to experiment with capturing more than one burst in the same photo.  Alternatively, you can capture a number of bursts and combine them later into one frame during post-processing.

 As the display goes on, the sky begins to fill with smoke.  This smoke reflects the light from the fireworks and can affect the exposure.  You may need to darken your exposure by stopping down your lens aperture by another stop or more. 

 

These rules should give you a good starting point.  Experiment by varying the lens aperture and the time the shutter is open.  Above all, be aware of where in the frame your bursts are recording and tighten up the crop if there is too much black area from the night sky.

 

Composition: Making clouds work for you

Every year over 3 million people visit the Statue of Liberty in New York.  It is a safe bet that all of them have a camera and take one or more photos.  That means that over 3 million images of the Statue of Liberty are taken annually.  With odds like these you may wonder if it is still possible to obtain a unique photograph of the famous statue of the lady in the harbor.  

The photo on the left is what anyone can achieve -- and millions do -- on a nice, cloudless day.  The photo on the right was taken from a scenic boat tour at sunset.  The uniqueness of the clouds and careful timing to include the sun just peeking out from behind the statue make this shot a one-of-a-kind composition.

You will need to shift your main focus from the static subject of your scene and concentrate instead on the changing landscape around the subject if you hope to create a composition that is uniquely your own.  Keep in mind that while the subject is fixed in space two things are not: you and your position relative to the subject, and the weather.  Taking advantage of these changing elements will result in an image you can call your own.  One thing is certain: the weather as reflected in the cloud formations over your subject is constantly changing and will never be exactly the same twice.  Make a compositional design relationship between the weather and the subject and you will have something you can call uniquely your own. 

This photo is of a statue at the Gettysburg Battle Field monument.  Careful placement of the clouds create a swirling effect that emphasizes the running motion of the soldier. 

 

First you must train yourself to look beyond the subject to the surrounding area.  Too often photographers "see" only the main subject they are photographing and ignore the subject's environment. 

These samples show the difference that a cloud formation can make to a photo when it is incorporated into the overall composition.  In the left photo the castle is centered in the frame without much relationship to its background.  In order to incorporate a large cumulus cloud formation into the right image, it was necessary to place the castle down towards the very bottom of the frame.  Inclusion of the cloud formation dictated compositional placement and lens focal length, both of which make for a much more interesting shot.

 

Working with clouds can often make a bad day look good.

I arrived at Stonehenge on an overcast winter day at mid-day.  This is usually the worst time to photograph a travel scene.  There was just enough blue sky peeking through the clouds to provide some color.  I decided to create a shot that would illustrate how the monument would look in relationship to its bleak landscape. A 28mm wide angle lens allowed me to include the upper limit of the sky.  This is important because the sky is a deeper blue higher up.  The actual subject takes up very little space in the frame.  Nonetheless, it stands out dramatically against the sky and surrounding plains, and further emphasizes the important relationship Stonehenge had to the environment.  About 80% of this photo is taken up by a rather humdrum sky.  Relating it to the main subject gives it a new meaning and makes this shot unique.

Sometimes you luck out with an unusual cloud formation.  Here the clouds form a halo effect above the church cross on the Island of Mykonos.  All I had to do was change my position to align the clouds with the cross.

Two completely different cloud themes of western scenes: On the left a small, single cloud suggests a dry, remote desert area.  In the example on the right a huge cumulus cloud formation over the Grand Tetons in Wyoming emphasizes the grandeur of the mountains and the landscape.

 

The weather does not have to be sunny to provide an opportunity for dramatic cloud compositions.

The church was placed over the bright area of the stormy sky to help define its silhouetted shape.

I found this storm cloud formation while driving though the South Dakota plains.  Pulling off the road at the next exit, I was able to grab a shot of the immense storm over the landscape.  The plains themselves take up a very tiny area at the bottom of the frame, and further emphasizes the relationship of the landscape to the sky.

These oil tankers were anchored off the shore while I was sailing in the Aegean Sea just before dawn.  A typical shot of this scene would be to make a horizontal composition by coming in tight on the ships with a telephoto lens.  To make the photo more unique I included the tops of clouds over the scene and changed the composition to a vertical.

 

Forming your composition by incorporating cloud formations in relationship to your main subject is a great way to give your photos a special look, and one that is impossible to duplicate ever again.  The photo becomes a reflection of your personal experience with a scene at a particular time and place.  Isn't that what good photography is all about?

Lenses: Introduction to Focal Lengths

The focal length of a lens refers to the actual length of the lens from a point inside its front lens element to the point where it comes to focus -- in our case, that is on the camera sensor -- when the lens is focused at infinity.  Modern optical systems and zooms can make this calculation more exacting, but this definition is sufficient to understanding the elementary difference between lenses and how to use them creatively.  Focal length is typically expressed in millimeters for modern DSLR lenses. 

What we call a "normal" lens is one where the focal length is approximately equal to the diagonal of the sensor plane.  On a full-frame (35mm) sensor that would be a 50mm lens.  On the smaller APS sized sensor that would be a 35mm lens.  All other focal length categories are given relative to what is "normal".  For instance, a wide angle lens is one that is wider that a normal lens, while a telephoto lens is longer than a normal lens.  

Wide angle lenses take in a larger visual area that makes them most suitable for wide landscapes, while telephotos act more like telescopes for close-up viewing of distant subjects.  These are the obvious, practical reasons for selecting one focal length over another.  More importantly, however, are the creative characteristics each focal length has.  

This introduction will give a brief overview of the most common focal length categories and their characteristics.  Later posts will cover each focal length separately and in more detail.

These photos illustrate the difference between four common focal lengths. All were taken at the same distance from the subject.  Upper left is a 28mm wide angle (18mm on APS sensor).  Upper right is a 50mm normal lens (35mm on APS sensor). Bottom left is a 100mm portrait lens (65mm on APS sensor). Bottom right is a 200mm telephoto (135mm on APS sensor).  You can notice from the relationship of the lions head to the background columns that when different focal lengths are used from the exact same distance all they do is crop or take in more of the scene.  To gain a creative benefit from the different focal lengths you need to take alter the distance of the lens to the subject.  This is illustrated in the samples below.

The four broad categories of focal lengths are: wide angle, normal, portrait, and telephoto.  The main creative difference between focal length categories is the sense of perspective they give.  Wide angle lenses tend to expand space, while telephoto lenses compress space.

Take a look at the sample photos. The 400mm telephoto lens used for the photo on the left produces a compression of space between the jumps and the jumper.  The 24mm wide angle lens used on the right produces a more "rounding" effect on the jumper and puts the viewer right into the action.

The long 200mm telephoto lens on the left compresses the scene by bringing the Independence Hall building in Philadelphia right up to the statue in front.  A 35mm wide angle lens used on the right relates the two in a very different way.

For any given aperture a wide angle lens will have more depth of field, that is it shows more of the background in focus when the lens is focused on the foreground.  Depth of field will be covered on its own in a later blog entry.

Wide angle lenses:

A wide angle lens is one with a focal range from around 14mm to 35mm on a full frame sensor, or 10mm to 28mm on an APS sensor.  The smaller the focal length, the more area the lens covers.  A 14mm lens (10mm on APS) would cover a viewing angle of 114° (81° with APS).  On the other, longer end of the wide angle spectrum, a 35mm lens would have an angle of view of 63°  (44° with APS).

The most obvious use of a wide angle lens is to gain a wide view of the subject.

In this photo of a departing storm and rainbow over the Grand Canyon, a 24mm lens on a full frame camera provided plenty of surrounding detail by including the blue sky in contrast to the departing stormy sky.  Relating the central subject of the storm and rainbow to its larger environment told more of the story of what this scene was all about, and gave a better sense of the immense scale of the Grand Canyon.

Wide angle lenses could be used creatively by placing them very close to the foreground area of a scene.  This establishes a relationship of the foreground detail to the background scene.  When doing this it is often best to place the focus in the front, and by stopping the lens down to around f/8-f/16 to provide a very deep area of focus, called depth-of-field (more on this topic in a later blog).

In this photograph of the giant sequoias a 24mm lens on a full frame camera was place right next to the tree trunk on the left and the camera pointed upwards.  This enhanced the sense of scale and provided a better idea of how large the trees are.

In this cityscape a 35mm wide angle lens was used to create an interesting sculptural frame of the Chicago city skyline

Normal lens:

The normal lens of 50-60mm on a full frame camera (35mm on an APS sensor)  is most closely related to the natural perspective the human eye has of the environment.  It is best used when you want to recreate a scene that feels natural, as if the viewer is actually part of it.  In a creative sense, a normal lens places the viewer in the scene without drawing attention to the fact that the camera was even present.  It downplays the role of the photographer in the scene.

Use a normal lens when you want to achieve a realistic perspective between the foreground subject and the surrounding scene as in the samples below.

Many normal lenses come with a very "fast", or wide open, aperture.  This enables them to be used in very dark situations without a flash.  The photo above was taken with available light in a dark barn using a 50mm lens set to f/1.4.  A normal lens is very good at relating a subject to its background without distorting the perspective.

In portraiture the normal lens provides story-telling detail by relating the subject to the surrounding area

Portrait Lens:

A "portrait" lens is so-named because it causes the most natural perspective on the human face.  In addition, it has a slight telephoto effect that throws the background gently out of focus.  This serves to put more attention on the main subject.

This illustration shows the difference in the perspective properties of a wide angle lens versus a portrait lens.  The photo on the left was taken with a 35mm lens on a full frame camera, while the one on the right was taken with a portrait lens of 85mm.  You can easily see how the wider 35mm lens distorts the face, making it unnaturally rounder, while the 85mm lens produces a flattering, natural look.

 Portrait focal lengths range from 70-110mm on a full frame camera (50-75mm with an APC sized sensor)

Here an 80mm lens kept the background scene of the mountains slightly out of focus so that they tell a story of where we are but do not compete with the main image of the cowboy.

Two examples of the 100mm lens delivering a natural perspective to the faces.  Placing the mother and baby on the same plane in the top photo kept both of them in focus and at the same time kept the background softly out of focus.

Using the same lens for the bottom photo but placing the mother and the baby on different planes allowed the mother's face to be sharp and the baby's to be soft -- a result of the longer focal length of the portrait lens.

Telephoto Lens:

Telephoto lenses range from 135mm on up.  The upper practical limit of the telephoto range is 200-400mm (135-300mm in APS), but even longer  lenses can be had at 600-800mm.  In addition to magnifying distant objects, telephoto lenses have the drawback of also magnifying camera movement.  A shutter speed that might be sufficient to stop camera motion with a 50mm lens needs to by three times greater to stop the same motion with a 200mm lens.  In other words, every time you double the focal length, you will need to increase the shutter speed the same amount.  For instance, 1/250 second with a 100mm lens is equivalent to 1/500 second with a 200mm lens.

Fortunately, most modern telephoto lenses are equipped with a vibration reduction technology that can effectively freeze the action for you and allow lower shutter speeds to be used hand-held with long lenses.  Still, it is best to use very long focal length lenses on a tripod to minimize motion blur by increasing steadiness.  With extremely long telephotos it is almost impossible to steady them without a tripod or monopod.

Compressed perspective and shallow depth of field are typical characteristics of the telephoto lens.

This photo of a football shot with a 200mm lens compresses the lines on the field and makes them very out of focus due to the shallow depth of field.

Notice how in this picture of Prague all the buildings and statues are compressed together in a "telephoto effect".

A telephoto lens is a great way to relate a foreground shape to a background as in this example of the pine trees echoing the shape of the Grand Teton mountain range.

Conclusion:

The real reason for choosing one focal length over another is not necessarily the practical one of simply including more or less of a scene, or putting you closer to your subject.  A more important point to consider when choosing a focal length is how it can contribute creatively to your image.  When you want to bring the viewer right into the action, a wide angle lens used up close would be the best choice. The compression effect of a telephoto lens will relate a foreground to background in a very different way than the expanse created by a very wide angle lens. You might want to switch to a normal or portrait lens in situations where you want to illustrate the subject in a more natural way.

In later blogs I will be providing an explanation of the important creative role the lens aperture of each focal length plays in the area of focus, or the "depth of field".

Photographing cities at night

The moment of perfect harmony:

The modern DSLR has made night photography easier than ever.  There are a few tricks you need to know to improve your photos beyond the ordinary.  First of all, let's discuss the equipment you will need.

A tripod or some sort of steadying device is mandatory.  Night exposures are long and camera blur will occur if the camera is not rock steady.  A cable release, while not necessary, is helpful for keeping your images blur-free.  The simple act of touching the camera to press the shutter button is enough to add some motion blur to the shot.  That said, I will also discuss some alternative work around for dealing with situations where you do not have a cable release or tripod.

Timing is the most important aesthetic element in taking night photos.  Photographs look better when there is some detail and color in the sky.  The ideal time to take your night shots is 10 to 20 minutes after actual sunset.  I call this time slot the "moment of perfect harmony" where the exposure for the sky is perfectly balanced with the exposure of the city lights. At this moment you will be able to record some detail in the sky, which often goes a bluish color.  Don't be afraid of taking night photos on cloudy days.  The sky will still turn into a nice deep blue background.  This is due to reciprocity failure, a topic I will cover in a later post.

Photographing into the west 10-20 minutes after the sun has set can add nice color and detail to the sky.  Notice how the lights of the city and the light in the sky are perfectly balanced.  In this case, proper timing of the shot gave plenty of detail everywhere with no heavy black areas. The exposure was f/5.6 at 4 seconds.

 

Here the photo of Washington DC was taken facing east so the setting sun was behind me.  The sky had no color or detail that was visible to the eye.  Nonetheless the camera recorded a very pleasing overall blue balanced against the lights of the Capital Building. Both situations had water foregrounds to reflect and amplify the colors of the scene. This also avoided a foreground that might have gone dead black.  Exposure of f/4 at 1/2 second.

Proper exposure is very easy with modern DLSR cameras.  For the most part, I find it easiest to put the camera in its "A" for "Aperture Priority" setting.  This allows you to select the lens aperture you want and have the camera choose the shutter speed.  While almost any aperture will do, f/5.6 or f/8 is often the most optimum optical setting for a lens.  You can check your results on the camera display and by looking at the histogram to see if it is balanced. You want the high parts of the histogram graph to be in the middle.  But be careful because your histogram can be skewed to one side or the other if there are large dark areas of very bright lights in the scene.  Best bet is to bracket your shot.  Do this by setting your camera to over expose by plus one stop and under expose by minus one full stop.  You can set most DSLR cameras to do this automatically for you, but that might be more trouble than it's worth for the few exposures you are going to take of a scene such as this.  My preference is to use the over/under (+/-) exposure button and dial on your camera.  With your camera still on the "A" setting, change the +/- setting to +1.  Take a photo. Change it again to -1 and take another photo. That should do it, but you could play safe and go for a +2 and -2 also.  You should be shooting in RAW because this will provide the most options for adjusting the exposure afterwards.  The JPG format will be too limiting if you do need to make exposure corrections on the image later on in post processing.

For this scene of the El Morro Castle in Old San Juan, Puerto Rico, I took the same photo several times over the 10-20 minute time frame.  My camera was pointing north.  The sun had just set to the left so the sky was brighter on that side.  In addition the lights on the castle were very dim and I wanted to be certain the exposure was perfectly balanced in both the sky and on the castle.  Later I had to dodge some of the light off the right side of the photo to bring it into further balance with the left.  To complicate matters even more, this photo was done in two shots that were later put together to make a panoramic image.  A steady tripod is absolutely essential for a shot like this done at a 1/2 second exposure.

Working without a tripod or cable release:

There are times when you do not have a tripod or cable release with you.  To steady the camera you will need to find a firm place to rest it.  Then you can prop something under the lens to gain elevation and angle it in the right direction.  I usually use my wallet or keys.  You can use the camera's self-timer feature instead of a cable release.  I usually set the time for a delay of 2 seconds.  Press the shutter and remove your hand from the camera and 2 seconds later it will take the exposure.  For extreme steadiness I often use a feature most DSLR cameras have to lock up the mirror.  When the mirror slaps up and down it causes a vibration that can blur your shot, particularly if you are using one of these emergency techniques for propping up the camera. That is the method I used to take the photo of the Coliseum below.

By the time I took this photo of the Coliseum in Rome the sky was already past its prime in the light envelope and came in dark.  To offset this I did a time exposure that included the light streaks from moving autos in the foreground.  The camera angle was very low.  In fact I placed the camera directly on the sidewalk and propped my wallet under the lens to angle it up.  In this case I used the camera in Manual mode and read the exposure for the scene without the car lights.  I wanted to keep the shutter open long enough to blur the lights of passing cars as streaks in the scene.  The exposure was f/8 at 5 seconds. I waited until I saw a large group of cars coming by and opened the shutter.  It took several tries to get it right, but the lights added interest to an otherwise dull foreground.

This scene of the Flatiron Building in New York was taken 10 minutes after sunset facing south.  There is still plenty of light in the sky.  An exposure of f/4 at 3 seconds was enough to record the passing cars as blurred lights.

The important thing to remember is that you want your pictures to have plenty of detail.  Try to avoid dead spaces of deep black.  Choosing the right time of day to shoot is critical, but proper placement of elements is just as important.

This dusk shot of the arch in Washington Square framing the Empire State building in New York is the result of carefully balancing the time of night with the artificial lights in the scene.  Photographed facing north the sky is a deep blue.  Any later and it would have been totally black and the shot would not be as interesting.  Adding to the interest is the light post on the right.  All of this is a result of achieving a perfect lighting harmony in the scene.