Taking Portrait Photos with Blurry Background and Understanding Depth of Field

We have all seen beautiful photos where the object is perfectly focused while the background is blurred. Such a photo can be very dramatic and might seem to be hard to shoot. In this article we will give you a few tips on how to shoot blurry background photos that will impress your friends and family. You will also understand what Depth of Field is and how to control it.

Depth of field (also known as DOF for short) is the most important thing to understand before shooting a blurry background photo. Depth of field is defined as the range in which the photo is in focus. For example an infinite depth of field means that the photo will be in focus from a certain distance from the camera and up to infinity. When taking a blurry photo the goal is to set the depth of field just around the object. In this way the object is in focus while the background behind it is not.

How do you control the depth of field? After all there is no “depth of field” menu in the camera (wouldn’t that be nice…). Depth of field is an optical figure that is influenced by a few factors:

The distance of the object from the camera: This is obvious to understand when taken to the extreme. Shooting an object 10 feet from the camera will result in a smaller depth of field than shooting an object 100 feet from the camera. Obviously shooting an object which for all practical purpose is infinite distance from the camera will result in the camera focused on infinity and the depth of field being infinite too..

The aperture: The wider the aperture (f number decreases) the smaller the depth of field and vice versa: the narrower the aperture (f number increases) the greater the depth of field. Just remember that the depth of field changes along with the f number: when the f number increases and depth of field increases and vice versa. Unfortunately you can not just change the aperture as you wish. Changing the aperture results in a need to change the shutter speed (either manually or the camera can most likely do that for you automatically). The wider the aperture the more light that penetrates the lens and the faster the shutter speed needs to be so there is a limit to how wide you can set the aperture to.

The focal length of the lens: The shorter the focal length the greater the depth of field and vice versa the longer the focal length the smaller the depth of field. For example if you use normal lenses at somewhere around 50mm your depth of field will be much greater than if you use zoom lenses at 200mm. With long focal length the depth of field can be extremely small. For that reason zoom lenses are a good choice in order to shoot a good blurry photo that is practically focused only on the object.

After understanding the theory it is best to go to the field an experiment. You will get a sense of how your photo will look like and how blurry the background will be after playing with different lenses, different apertures and different distances from your object. If you own zoom lenses start with taking photos of a relatively close object while using your zoom lenses. You will find out that it is extremely easy to get a blurry background photo using this method even without setting the aperture. Once you feel comfortable with that setup start changing the aperture and also change to your normal 18mm-55mm or similar lenses.

Most cameras allow to manually change the aperture by putting the camera in “A” mode – while you are changing the aperture the camera will automatically set the shutter speed accordingly. Some cameras allow you to manually set both aperture and shutter speed.

In conclusion shooting dramatic blurry background photos is easy with some minimal understanding of depth of field and some experimenting.

Understanding Red-Eye in photos and how it can be prevented

Why are eyes red in photos?

Red-eye is a phenomenon that happens only when taking photos using a flash. When taking photos in day light or when in high ambient light scenarios people’s eyes look normal. When taking pictures in low ambient light scenarios using a flash the result many times is redness in the people’s eyes.

The reason for the color red is simple – when flash light from the camera hits the eyes it penetrates and is reflected back from the retina. The color of the reflected light is red because the light is actually reflected from the red blood in the retina.

In some scenarios the red-eye is evident while in others it is mild or doesn’t seem to appear at all. One of the main factors for that is the state of the pupils. If the pupils are dilated (for example the pupils dilate in darkness or when drinking alcohol) more light is reflected back from the retina and the eyes in the photo appear redder.

Common way to reduce red-eye

The most commonly used method to reduce red-eye is activating the camera’s built-in red-eye reduction feature. The red-eye reduction feature is very simple yet effective. When turned on the camera shoots a series of pre-flash strobes followed by one more strobe when actually taking the photo. The pre-flash strobes cause the pupils to reduce in size and by the time the photo is taken the pupils are small enough for the eye redness to substantially reduce.

The red-eye reduction feature does what it is supposed to do: reduce the red-eye effect but almost never is it completely prevented. There are many limitations to this feature for example pupils reaction time to light can vary. In addition this feature can have a side-effect that results in photos having people’s eyes closed. The reason is that the pre-flash strobes blind the people and cause them to close their eyes.

Other ways to prevent red-eye

Understanding what causes red-eye helps being more creative in preventing it. Following are some ways to prevent red-eye other than using the built-in camera red-eye reduction feature:

Increasing the light where photos are taken (for example by turning on the lights in a room before taking photos of people) causes people’s pupils to reduce in size and eye redness to reduce.

Point the flash away from the eyes. Since red-eye is caused by flash light reflected from the retina the best way to prevent red-eye would be to eliminate such reflection as much as possible. In most cameras the angle between the flash and the lenses is narrow (this is especially true for built-in flash and pocket cameras) causing most of the flash to bounce back from the retina to the lenses. Increasing the angle (for example by using an external flash) reduces the reflected light. You can also use a bounce flash – by having the flash light bounce off a bright surface (a white wall or a professional reflector) most of the direct reflection from the retina can be eliminated.

Red-eye can also be removed after photos were already taken by using photo processing software on your PC. Most digital cameras include a CD with PC software that embeds this feature. Although this method doesn’t eliminate the red-eye from the source it can result in a practically red-eye free photo. Some software are better than others some are manual while others automatically identify the red-eyes and process that area to revert to normal eye colors.

Understanding Shutter Delay in Digital Cameras

When using a digital camera to take action photos you will notice that there is a delay between the time you press the shutter button to the time the camera actually takes the photo. In most cases this delay is small enough and not noticeable but when taking action photos, when trying to capture an event that just happened or when trying to capture a moving object this delay can result in a photo that just missed the action. In this article you will better understand what causes the shutter delay and how you can overcome it.

A shutter delay is defined as the time gap between pressing the shutter button to the camera actually capturing the photo. There is no shutter delay in film cameras as in these cameras the shutter button is virtually connected to the shutter itself and holding down the button results in the camera taking a photo immediately. In digital cameras the shutter button is connected to a built-in micro computer and holding down the shutter button initiates a series of events that result in capturing a photo.

When you press the shutter button the camera goes through a series of setup events in order to get all its electronics ready. Only when these events are finished can the camera capture the photo. The time it takes for the camera to complete these events can vary but is usually around one second or so. When taking subsequent photos there is an addition delay as a result of the camera compressing the photo and writing it to the slow flash memory.

Although a circa one second delay does not seem long it can make the difference between capturing an action photo to missing it. Some cameras will also initiate a focus process when the shutter button is held down and will only take the photo when the focus is completed. This can add even more delay.

Although it is impossible to remove the shutter delay in your camera there are few practices that can help avoiding its results. For example many cameras include a burst mode. In burst mode the camera shoots a fast series of photos for as long as the shutter button is held down or until the camera’s memory is full. In this mode the camera writes the photos to a temporary memory which is very fast but small. When the shutter button is released or the memory is full the camera starts the slow process of writing the photos to the flash memory.

Using the burst mode you can shoot fast photos of an action event and then choose the one that best captured the events. The speed and the amount of photos that the burst mode supports vary between cameras. Some high end cameras can take as much as ten photos over the course of one second.

Another delay that is a result of the digital camera technology is the Initial Delay. Most cameras will enter into a standby mode if not used for a certain amount of time. This time can vary but it’s usually in the few minutes range. When the camera goes into standby mode it turns off most of its electronics in order to save power. Usually pressing the shutter button will restart the camera but such a restart process is long and can take a few seconds. The result is a longer delay when taking a photo after the camera was idle for some time. In order to avoid this you would have to make sure that your camera is turned on and does not go into standby mode when taking action photos. Some cameras allow you to disable the automatic standby feature through a menu option. If your camera does not allow that you can keep it on by pressing the shutter button half way down every now and then. The downside of leaving the camera on all the time is wasting battery power. In order to maximize battery life in such scenarios you can disable the camera’s LCD screen which consumes a lot of energy and use the view finder instead.

Another way to minimize the shutter delay is to avoid the automatic focus process which usually starts when the shutter button is held down. One way to do that is to hold the shutter button half way down. In most cameras the result will be a one time focus process and then a focus lock. The camera will stay in focus and when the shutter is fully pressed it will take a photo without re-focusing. Another option is to put the camera in manual focus.

It takes practice to get to know your camera and to get a feeling of the delays it introduces. Although there is no way to completely get rid of the delays you can master overcoming them by practicing taking action photos. New high end professional cameras have a very short delay and as the electronics improve cameras will eliminate the shutter delay altogether.

Understanding Photo Printing Paper Sizes or What is 4XD?

What is an aspect ratio?

Every photo or movie has an attribute called an Aspect Ratio. The aspect ratio is the relation between the horizontal and vertical sizes of the photo. To calculate the aspect ratio simple divide the width or a photo by its height. For example TV in normal mode has an aspect ratio of 4:3 or in other words if we were to divide the width of the screen by its height the result would be 4/3. TV in widescreen format on the other hand has an aspect ratio of 16:9.

When we take a photo with a camera light that travels through the lenses hits a sensor (a film in traditional cameras or a CCD in digital ones). The sensor in turn translates the light into a two dimensional photo. The sensor itself has physical attributes such as width, height, granularity (in films) and number of pixels (in digital CCD sensors).

The connection between an aspect ratio and photo printing

When photos are printed on paper the aspect ratio of the paper must be the same as the aspect ratio of the sensor that was used to take the photo. If the aspect ratios are different the result will be a blank area left on the paper or a stretched photo that fits the paper but distorts the objects in it.

Why does it happen? The answer is pretty simple. For the sake of explanation lets assume a photo sensor that is 6 inches wide and 4 inches high (real sensors are much smaller). Lets assume that we are trying to print the a photo taken with that sensor on a paper that is 4 inches high. If the paper width would be less than 6 inches we will have to crop part of the photo since there won’t be enough space available on the paper. If the paper width is more than 6 inches we will have to leave a blank area on the paper since we do not have “enough photo” to print on more than 6 inches. If we want our photo to exactly fit the page we can stretch or shrink the photo horizontally to whatever the paper size is – but then the objects in the print will be distorted and look more fat or thin as they were in real life.

Printing on a 4X6 paper

One of the most common paper sizes is 4X6. This size was used for many years for printing photos taken with traditional film cameras. The traditional film had an aspect ratio of 3:2 and thus the photos taken with a traditional film camera would fit perfectly on a 4X6 papers.

For reasons beyond the scope of this article digital cameras use sensors with a different aspect ratio than tradition film cameras. The following table summarizes popular image sizes in pixels and the respective aspect ratio (sensor pixels, width X height and aspect ratio):


2 MP – 1600 X 1200 – aspect ratio 4:3

3 MP – 2048 X 1536 – aspect ratio 4:3

4 MP – 2272 X 1704 – aspect ratio 4:3

5 MP – 2592 X 1944 – aspect ratio 4:3

6 MP – 2816 X 2112 – aspect ratio 4:3

8 MP – 3200 X 2400 – aspect ratio 4:3

As can be seen digital sensors, regardless of the number of pixels they support have a 4:3 aspect ratio.

So what happens when we try to fit a digital photo on a 4X6 paper? The photo just doesn’t fit! it is either too wide or too high. For example if we want to print on the full 4 inches height we will only fill 51/3 inches (4X51/3 is a 4:3 aspect ratio) and 2/3 inches will be left blank.

To solve this problem and use the full paper size many printing services allow the user to crop a part of the photo. The assumption is that instead of leaving a blank area on the print the user would prefer to cut a part of the photo that is not important and use the whole paper for the rest. Some services allow the users to choose a preference for either cropping the photo or leaving a blank area on the print and this preference is automatically applied to all his prints.

What is a 4XD paper?

In light of the popularity of digital cameras and digital prints many printing services are introducing paper sizes that are designed for digital prints. This means that the aspect ratio of the paper they offer is 4:3 and thus photos taken with digital cameras perfectly fit the paper.

The new digital compatible paper sizes have an aspect ratio of 4:3 (the digital sensor aspect ratio) and are as close as possible to their traditional film paper sizes. So – in the digital world a 4X6 paper size will actually become a 4X5 1/3 (a 4:3 aspect ratio paper size that is as close as possible to a 4X6 size).

As a marketing gimmick and instead of writing exact paper sizes many use the “digital” abbreviation of 4XD – which means 4XDigital or in other words “as close as we could make it to 4X6 that is digital camera aspect ratio compatible”.

As digital cameras become more and more popular it is expected that more papers sizes which are digital camera compatible will be introduced. In a few years from now most printing services will support the digital paper size by default and the film compatible one will be the exception.