Let’s try to define depth of field. The usual definition runs something like this:

"The region over which objects in an image appear sharp".

While there is some truth in this, there’s also some confusion – and some untruth too! Let’s try a more accurate definition:

"The depth of field is the range of distances reproduced in a print over which the image is not unacceptably less sharp than the sharpest part of the image".

This definition contains some important points.

• First, DOF relates to a print or other reproduction of an image. It’s NOT an intrinsic property of a lens. If you put a lens on an optical bench you can measure focal length, you can measure aperture, but you can’t measure depth of field. Depth of field depends on some subjective factors which I’ll discuss later.
• Second, note the phrase "not unacceptably less sharp". All parts of an image which come from outside the focal plane of the lens are blurred to some extent. Only one plane is in focus. As you move away from that plane things get less sharp. The depth of field limits are where the loss of sharpness becomes unacceptable – to a "standard" observer.
• Third, note the phrase "..not unacceptably less sharp than the sharpest part of the image…". This covers the case of a pinhole camera. Such a camera has a very, very large depth of field (almost, but not quite infinite). However none of the image is sharp. The depth of field is large because all the image is equally blurred!

An important thing to note is that depth of field is NOT what some people think it is, i.e. a well defined zone over which everything is in sharp focus. Some people seem to have the impression that an image has two zones. In focus and out of focus. In fact there is only one point (actually plane) in focus. Everything else is out of focus to some extent.

Depth of field is also NOT directly related to background blur. Depth of field equations tell you over what range of distances objects will appear to be acceptably sharp (or at least not unacceptably unsharp). It tells you nothing about how much blur there will be of objects well outside the depth of field. That’s governed by different physical parameters and determined using totally different equations.

http://www.learndigitalphotographynow.com/

Before you start shooting night photos, here are the three most important things to remember:

• Disable your flash
  Bring out breathtaking detail in low-light conditions by using a long exposure (the time your camera takes to collect light).

  Select Flash from the capture menu, then select Flash off. Press Menu/Ok.

• Use a tripod
  Long exposures require you to hold your camera perfectly still to avoid blurring. A tripod really helps. If you can’t get your hands on one, you can try bracing yourself against a stationary object like a tree, or a wall.
• Use your timer
  Even when a camera is on a tripod, your finger pressing the trigger can cause enough movement to blur a photo. You can avoid touching the camera altogether by using the timer.

  Select Timer from the capture menu and press Menu/Ok.

http://www.learndigitalphotographynow.com/

Arrive early. The best time to shoot is before it gets totally dark. Arriving around sunset will give you time to plan your shot before the good light happens. You may have to ask your subject to turn the lights on early – most people don’t flip them on until the good light is already gone.

Shoot a test shot every minute or so. At first, you’ll be exposing for the sky and the lights will appear unimpressive. Check the back of your camera after each shot to watch the Christmas lights appear to "come up" as the ambient light level goes down. (Aren’t digital camera great?) Your eye is constantly adjusting to compensate for the dropping light levels, but the changes will be happening nonetheless

.

Somewhere in between sunset and full dark, the Christmas lights and the ambient light will start to mix beautifully. You’ll have about a 10-minute window which will give you a nice series of subtly different lighting variations. Remembering to keep your camera as still as possible, shooting lots of frames through the mix light. Ones and zeros are free, so don’t be stingy. You do not have much time. You can delete the duds (or blurred photos) later.

Incidentally, this time of day is when the architectural photographers make the big bucks. And they are smart enough to tell everyone in their subject building to leave the lights on that night, too.

Your light will fade very quickly. You will know it is gone when your photos start looking like the "bad light" photos you used to take.

Now, put your camera away. You still have a few minutes to enjoy the scene with your eyes. The human eye has the remarkable ability to compress a large dynamic range into a scene your brain can process. Just relax, soak it in and think about all of the shopping you have left to do.

This is one of the few times that both shooting pictures and enjoying the moment do not conflict with each other.

http://www.learndigitalphotographynow.com/

The sun is the most powerful light around, and even though we can’t move it around, we can control its effect on what we shoot.

• If possible, avoid shooting in the middle of the day, when the sun is directly overhead, creating harsh shadows or "raccoon" eyes on the subject’s face.
• If you must shoot at midday, a highly reflective surface such as a car dash reflector placed under the subject’s chin can brighten up shadowed features and add a warm glow. This light can, however, be intense and can cause watering of the eyes. A piece of white posterboard can also be used and should provide enough reflection to fill out the face.
• If reflectors are not an option, the subject can be moved to a shaded area to prevent harsh shadows and squinting. If you choose this option, make sure the background is shaded as well. If the background is too bright, the automatic iris turns the subject into a silhouette as it tries to compensate for the sun.
• Finally, if you can choose your shoot time, the best hours are just after sunrise and just before sunset. These hours are called the "golden hours" due to the orange hues that make everything look better.

Now, it’s time to go out, play around and experiment. If you aren’t satisfied with the results, you can always rewind the tape and shoot again.

http://www.learndigitalphotographynow.com/

Modern digital cameras have sophisticated ways of controlling the aperture and shutter speed. In fully automatic mode the camera sets them both to produce the best possible exposure. However, there are other exposure modes that are widely used in digital photography. All modes give equally good results in the vast majority of photographic situations. However, when you photograph in specific kinds of situations, each of these exposure modes may have certain advantages. Let’s take a look at the modes you can expect to find on some or all digital cameras.

• Automatic mode sets the shutter speed and aperture without your intervention. This mode allows you to shoot without paying attention to settings so you can concentrate on composition and focus.
• Scene modes have preselected settings for specific situations such as landscapes, portraits, night portraits, sports, and close-up photography.
• Programmed mode is just like full auto in that it sets the aperture and shutter speed for you so you can concentrate on composition and action. When in this mode, many cameras have a flexible program mode that lets you select from a series of paired aperture and shutter speed combinations that yield the same exposure as that recommended by the camera but which give you control over depth of field and motion.

One reason to use flexible program mode is that it doesn’t let you choose settings that exceed your camera’s exposure limits. In shutter-priority and aperture-priority mode it’s possible to select a setting that can’t be matched. For example, in aperture-priority mode, you may pick an aperture that’s so large the camera doesn’t have a shutter speed that’s fast enough to prevent overexposure. Although aperture-priority and shutter-priority modes usually warn you when this happens, you won’t always notice the warning. Here are some of the situations you avoid when using programmed mode.

• Shutter-priority mode lets you choose the shutter speed you need to freeze or deliberately blur camera or subject movement and the camera automatically sets the aperture to give you a good exposure. You select this mode when the portrayal of motion is most important. For example, when photographing action scenes, such as those encountered by wildlife photographers, sports photographers, and photojournalists, shutter-priority mode might be best. It lets you be sure your shutter speed is fast enough to freeze the action or slow enough to blur it.
• Aperture-priority mode lets you select the aperture needed to obtain the depth of field you want and the exposure system automatically sets the shutter speed to give you a good exposure. You select this mode whenever depth of field is most important. To be sure everything is sharp, as in a landscape, select a small aperture. The same holds true for close-up photography where depth of field is a major concern. To throw the background out of focus so it’s less distracting in a portrait, select a large aperture.
• Manual mode lets you select both the shutter speed and the aperture. You normally use this mode only when the other modes can’t give you the results you want. Some cameras have a bulb setting in this mode that lets you capture time exposures such as light trails at night.

http://www.learndigitalphotographynow.com/

If anything can go wrong, it will. Here are some of the things you might encounter.

1. If the camera seem to be turned off, it may just have entered sleep mode. If you don’t use any controls for a specified time, the camera enters this mode to reduce battery drain. To wake it up, press the shutter button halfway down, or turn the camera off and back on. After an hour or so of inactivity, some cameras shut off completely. You can often change the time it takes before the camera enters sleep mode or turns off completely.
2. If you can’t turn on the camera, the batteries are dead or have been removed or a memory card hasn’t been inserted.
3. If your batteries drain quickly, stop using the monitor to take and review pictures. If it’s cold, keep the batteries or camera under your coat.
4. When you turn the camera on, a battery shaped icon on the control panel indicates when the batteries are fully charged, getting low, or run down empty and should be replaced immediately.
5. When you turn on the camera, an error message will be displayed if there is a problem with the memory card.
6. If you can’t take a picture, it may be because the memory card is full. To free up room for new pictures, move the images to a computer and erase the memory card, delete some you don’t need, or switch to a smaller image size.
7. Some cameras have a delay between your pressing the shutter button and the shutter opening. This can cause you to miss fleeting expressions.
8. To control which part of the scene the camera focuses on, read your user guide so you understand how focus works in various exposure modes.
9. If the focus lamp blinks when you press the shutter button halfway down, the camera may be having trouble focusing.
10. If flash photos are too dark, you are probably too far from the subject. Most built-in flash units are good only up to about ten feet. They don’t have the power to illuminate subjects much father than that.
11. If photos are too light when using flash, you may want to reduce the flash power.
12. If your pictures are blurred, you may not be holding the camera steady as you smoothly press the shutter. Most blurry photos are caused by jabbing the shutter button. You may also be too close to the subject or the subject may be moving too fast.
13. Never take pictures of the sun or other bright light sources. Doing so can injure your eye or the camera’s image sensor.
14. If your pictures are not at all the way you expect, it may be because the camera remembered a change you made in the settings and continues to use that changed setting. Some cameras remember changes even when you turn a camera off and back on. See if your camera has a procedure that resets all settings to their factory defaults.

http://www.learndigitalphotographynow.com/

If you prefer to go on sightseeing holidays rather than flopping on a beach then you’re probably going to want to take photos of the buildings you visit. The trouble is you’re always there at the wrong time of day, the light is coming from the wrong direction, there are crowds of people blocking your view and the rest of the family are nagging you to put the camera away and get moving. You could just buy the postcard but, if you are a photography junkie like me, that will never be an option. Although sometimes I might buy a postcard as an insurance policy in case my photos are not good enough.

The best time of day to take photos of any outdoor subject is either the early morning or the evening when the sunlight has a reddish hue and the light is coming from the side rather than directly overhead. Early morning is best, there is a difference in the quality of light that I find it hard to put my finger on, also there are normally less people around. Obviously if you are photographing buildings the best time of day is going to be dictated by which way the building is facing. The photo on the right was taken at about 7.30am, I had spotted the building the day before but the light was all wrong so, as it was close to the hotel where I was staying I decided to go back in the morning.

As with any other type of photography you should ask yourself what it is about this particular building that you like and focus on that. Sometimes this will mean framing the whole building, sometimes it will mean picking out details and sometimes a mixture of both will work well. In the photo above it was the tower on top of the building that caught my eye but I found that I needed at least some of the building to give the tower context.

http://www.learndigitalphotographynow.com/

Things you can do with a tripod that you can’t do without one.

1. Take pictures at slow shutter speeds without getting the dreaded camera shake. This enables you to do lots of interesting things like having some, non-moving, parts of the picture sharp while other, moving, parts are blurred. In the picture on the right the water takes on a cloud like quality due to the slow shutter speed.

   Also panning with a moving object, like a car, is easier with a tripod. Panning at a slow shutter speed will render the object (car) sharp and the background as blurred streaks. (see the bicycle picture on Shutter Speeds and Apertures)

2. Use much smaller apertures giving you greater depth of field. Because you can use slower speeds you can shoot at any aperture you like. (see the coffee bean photo on Shutter Speeds and Apertures)
3. Shoot a series of frames that will join up into a panorama more accurately. Although this is possible hand held, the best way to shoot panoramas is to shoot in upright format, take lots of pictures that overlap and use a tripod that has been carefully adjusted to be level with the ground.

http://www.learndigitalphotographynow.com/

In this clip from our step by step beginner guide to digital photography, learn basic digital photography tips and techniques, including how to capture a vision with a digital camera. It’s digital photography made easy.

http://www.learndigitalphotographynow.com/

Basic lens cleaning tools are a blower, a microfiber cloth, and lens cleaning fluid (my favorite: Zeiss). Try to blast dust off the lens with the blower or canned air. Finger prints can be removed with a circular wipe of the new miracle micro fiber cloth (my favorite brand is Pentax because it is nice and thick; about $6). Persistent dirt should be removed with lens cleaning fluid, of which the safest is probably Kodak. Always drip the fluid onto the cloth and then wipe the lens; never put fluid directly onto a lens.

Even if your lenses don’t look dirty, every few months you should give exposed surfaces a cleaning with Residual Oil Remover (ROR). Even if you were able to protect your optics from all environmental sources of filth, there would still be crud condensing on your optics as camera bag plastics outgas. It is tough to verify ROR’s claims, but the optics do look visibly clearer after an ROR treatment and the $4.50 price won’t kill you.

If you are going to use an expensive lens in a dusty or wet environment and don’t want to obsess over your equipment, keep a B+W UV filter on the lens and count on replacing the filter every year or two.

http://www.learndigitalphotographynow.com/