Friday, November 8th, 2013

Depth of Field – how to use it in your photography

Once you  know how to achieve  different depths of field, the question then becomes when would you use this in your photography?

Once you understand how you can achieve different depths of field in your photography – the question then becomes when would you use this knowledge to craft better photos?

Portraits and a shallow depth of field

There are a number of situations where it is a good idea to have a shallow depth of field and one of these is for portrait and pet photography. In this case you will want to remove any distracting background from around your subject. When the background is cluttered or distracting, a shallow depth of field helps you to isolate the subject from the background.

To achieve this effect, you would do one of these things or a combination of them:

1    Use a zoom lens and zoom in to your subject,

2    Get closer to the subject, and

3    Set your camera to use a large aperture, such as f/2.8 – f/3.8.

When you do this, take care to focus carefully on the subject. One disadvantage of working with a very shallow depths of field is that the amount of the area in the image that is in focus is very small so if you don’t get your focus right, your subject will be out of focus. You need to make sure that what you want to see in focus is the area you are focusing on.

Photographing flowers and products

Another situation in which you may want to use a shallow depth of field is when photographing flowers. The closer you get to the flower the more likelihood the background will be attractively blurred.

In product photography, you may also want to get a shallow depth of field and you’ll find that in many cases, the shallower the depth of field, the more attractive the image is. The difference between a shallow depth of field and a deep depth of field can often be the difference between an attractive photograph and one that looks more like a snapshot.

Landscapes benefit from a deep depth of field

While a shallow depth of field is extremely attractive for portraits and many other types of photographs, when you’re shooting landscapes and cityscapes you will typically want the opposite to be the case and you will want a deep depth of field. For landscape photography, you’ll typically want everything in the image to be in focus.

When photographing landscapes photographers often talk about hyper-focal distance. The hyper-focal distance is the point at which you point your camera at to focus the shot so that everything from that point to infinity is in focus and, in addition, an area halfway from the hyper-focal distance to your camera is also in focus. The image shows you how this hyper-focal distance affects the depth of field.

For landscape photography, you’ll typically want to use a small aperture such as f/9 – f/11, a short focal length such as 17mm and be a good distance away from your subject. Calculating the hyper-focal distance then becomes the issue. In many cases, people simply opt to focus the camera at infinity as this typically gives good results without needing technical calculations.

Too much of a good thing

If you’re tempted to increase the depth of field by simply dialing down your aperture to the smallest possible size such as f/35 or so, think again. While it may seem that this will give you a very deep depth of field it can be counterproductive. At very small apertures an effect called diffraction kicks in and this can cause a decrease in quality in your images. Instead you need to find the sweet point at which the smaller aperture gives you a good depth of field but stop short of where it gets so small that light is diffracted decreasing the image quality.

DSLR vs Point and Shoot for controlling Depth of Field

When you’re looking to achieve different effects with different depths of field, you’ll find that a digital SLR will give you much better results than a point and shoot camera. The reason for this has to do with the relative sensor size of the cameras – the larger the sensor size – the more control you’ll have over the depth of field.

Understanding depth of field and how it impacts the images that you take is a key way that you can impact the quality of your images. Choosing the right option for each shooting situation and knowing how to set your camera to achieve the desired result will enhance your photos.

 

Helen Bradley

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posted by Helen Bradley @ 3:29 pm1 Comment links to this post

Tuesday, October 29th, 2013

Controlling Depth of Field in your Photographs

Learn what depth of field is and how your camera settings affect it

Some subjects need to be fully in focus to be shown at their best and others need dreamy out of focus backgrounds to create the right setting. The feature that is key in both situations is called depth of field – it gives you both that ‘everything in focus’ look and it also gives you soft out of focus look. Depending on what you are photographing getting the depth of field right is often the difference between a snapshot and great image.

I’ll explain what depth of field is and how to control it with your camera settings.

What is depth of field?

At its simplest, depth of field is the zone of sharp focus in front of, around and behind the subject in your photo when you are focused on that subject. When you have a shallow depth of field, only a small area around the subject will be in focus and quite often only a small part of the subject will be in focus. Everything else in the image will be out of focus with things further away from the subject, either in front of or behind the subject, being more out of focus the further away they are. This image has a shallow depth of field – it’s a great way to shoot flowers:

When the depth of field is deep, nearly everything in the shot is in focus. You control the depth of field in your images by adjusting the camera’s settings for aperture, adjusting the focal length of the lens and the distance you are from the subject. This image has a deep depth of field – that’s important as we want to see everything in this scene from the grass in front of us to the horizon miles and miles away.

Let’s look at each of these in turn.

Control depth of field with aperture

One way that you can control the depth of field in an image is to change the aperture that you are using. For this, you will need to have your camera set to Aperture Priority or Manual mode. Selecting an aperture that is very large, such as f/1.4 to f/2.8 will give you a shallower depth of field around your subject. The aperture used for this image was a huge f1.4 so only a small portion of it is in focus:

 

If you shoot with a small aperture, such as f/9 to f/11 or more you will find that more of the image will be in focus, which gives you a deeper depth of field. If everything else stays the same, the difference in the aperture setting you use can result in a very different image. The aperture used here was a small f11:

One benefit of shooting with a large aperture, such as f/1.4 to f/2.8, is that a lot of light is getting into the camera so you can use a fast shutter speed. Conversely, a down side of shooting with a small aperture such as f/9 to f/11 or more is that less light gets into the camera so you will need to use a slower shutter speed  or a higher ISO value. In some cases you will be shooting with such a slow shutter speed that you will need to use a tripod.

Control depth of field with focal length

The focal length of your lens can also have an impact on the depth of field when you use this to make a subject bigger. So, if you are shooting with a 50 mm lens, you will get a much deeper apparent depth of field than you would if you were capturing an image with a 200 mm lens at the same aperture and if, in both situations the subject size is the same. The depth of field is actually not significantly different but it looks different because there is more background in an image when you capture it with a 50mm lens than you will get when you capture it with a 200 mm lens. So a rough rule of thumb is that the more zoomed into the subject that you are, the shallower the depth of field will appear to be. This giraffe was shot at f5.6 which isn’t a particularly large aperture but it was shot at 300mm zoom so the giraffe is quite sharp and the background is nicely out of focus:

 

If you are shooting landscapes you will get best results when you use a short lens such as a 28 mm lens as the image will appear to have a much deeper depth of field. On the other hand, a zoom lens can be a good lens to use when shooting portraits because the further you’re zoomed in to the subject the less background will be in the image and the shallower depth of field you will appear to have. This image was shot at f11 with a 28mm lens so everything from the lamp post to the building is in focus:

Control depth of field by varying the distance from your subject

The distance between the subject and the camera is another way that you can impact depth of field. So, for example, if you photograph a subject close up, such as in the region of up to 10 feet away, then the depth of field will be much shallower and more of the image behind the subject and a little in front of the subject will be out of focus. On the other hand, if you move the subject further away from you so that the subject is 20 feet away then the depth of field will be much deeper and there will be a lot more of the image in front and behind the subject in focus. This image was shot with a 200mm lens – the singer was relatively close to the camera  and the background was some distance behind him so the musician is in focus and the background nicely out of focus:

Whenever you’re considering depth of field, you should also note that, when the subject is in focus, the amount of the image that is in focus behind the subject will be greater than the amount of the image that is in focus in front of the subject. The ratio is approximately one-third to two-thirds, so the depth of field will extend roughly one-third in front of the subject and two-thirds behind the subject.

Helen Bradley

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Tuesday, October 30th, 2012

7 Camera Settings for Capturing Better Photos

Whether you are using a Point and Shoot or a DSLR camera here are seven camera settings that will help you capture better photos:

Tip 1 – Adjust for light

Most digital cameras, in particular SLRs, let you select ISO film equivalencies. Choose 100 – 200 sensitivity for photographing in bright light conditions and use 400 – 800 when there is less light.  In very poor light you can capture at 3200 – 6400 or higher but you will find that, as a result, there will be more film grain visible in the final image a a result.

To capture an image like this at night you should have an ISO setting of at least 800 -1600 or higher and a tripod to steady the camera.

Tip 2 – Choose your mode

Most cameras, in particular point and shoot cameras have settings for portrait, landscape, night shooting, sports, etc. Choose the correct mode for the type of conditions and the camera will automatically configure the ideal settings to ensure the best shots in the available light conditions.

For an image like this choose Landscape mode so it is all in focus.

Tip 3 – Depth of field

Use your camera’s Aperture Priority setting and set the aperture to a small f stop such as 2.8 to capture photographs with an interesting depth of field. Focus the camera on the object to appear in focus and, when you do, objects in front and behind this object will appear pleasingly out of focus.

Here I focused on the girl in front with a very small f stop and she is in focus – the girl facing us is not.

Tip 4 – Axe the digital zoom

Of the two types of digital camera zoom, which you will find in both point and shoot cameras and camera phones only Optical Zoom is a true zoom . If your camera offers digital zoom it is best to disable it or avoid using it. Digital zoom merely increases the size of the image captured and crops away the area not required. Optical zoom actually zooms into the scene to capture it at full size.

 

Tip 5 – Adjust exposure

Avoid over or under exposed photos using your camera’s exposure compensation settings. These can usually be adjusted to somewhere between -2 to +2EV. To lighten a shot use + values and to darken one, use – values.

Here is the same Boston building captured at -2, 0 and +2 exposure – the one on the right is the better exposed shot.

Tip 6 – Set the correct White balance

Different light sources throw different color casts onto your photos. For instance, inside lighting such as florescent and tungsten globes will throw blue/green or orange tints onto your image. When shooting indoors without a flash, set the white balance mode to match the light source, to remove any undesirable color cast.

This camera is set to an ISO of 80 (suitable for a very bright day) and AWB – Auto White Balance – this  means the camera will adjust the white balance – not good for indoor shooting but should be fine out of doors in full sun.

 

The image on the left was shot in tungsten light with no white balance adjustment. The one on the right was shot in the same position but with white balance set to tungsten light – the color is much improved.

 

 

Tip 7 – Set the Flash

Use your flash when capturing portraits on a very bright day. While it may seem counter productive, the flash will light your subject’s face and avoid the deep shadows that the overhead sun will cast on their face.

On the left the little girl is captured with no flash and over head sun. On the right I fired the flash and her face and clothes are more evenly lit.

 

Helen Bradley

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posted by Helen Bradley @ 10:37 amNo Comments links to this post

Monday, February 20th, 2012

Shoot right at night – Tip #1 – Get the light

When the sun goes down, a world of different lights opens up and it’s a great time to pull out your camera for some stunning photos. However, before you go out to shoot at night, there are some things to think about that will help you take great shots even when the lighting isn’t ideal.

Today we’re starting a new tip series – shooting right at night and here’s the first tip:

Make light or capture what little there is

At night, there’s obviously less light than there is during the day. So, to get good shots you either have to replace the missing light with a flash, or open up the aperture so more light gets in and slow the shutter speed so the camera gets enough light to register the image. You can also up the ISO – in the next few tips we’ll look at each of these options in more detail and find some great topics for shooting at night.

 

 

Helen Bradley

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Tuesday, February 8th, 2011

Understand your camera’s settings – Part 3 – ISO

Image: ISO3200, f5.6, 1/80s – the high ISO gives good sensitivity to light allowing this image to be captured quite fast in a relatively dark NY subway station.

In part 3 of this series on understanding your camera’s manual settings I’ll explain how to combine a choice of ISO settings when varying Aperture and Shutter speed.

In addition to Aperture and Shutter speed you can also configure your camera’s ISO setting. You would do this to adjust for the situation where there is not enough light for a shot or where there is too much light.

ISO is the camera’s sensitivity to light and small ISO values such as 80 and 100 indicate low sensitivity so the camera needs more light to take the photo. High values like 400 and 800 (and even up to 6400 and beyond) increase the camera’s sensitivity to light and can be used when you need more light, for example, where the shutter speed or aperture you want to use can’t give the light you want.

Take care when using very large ISO values as these are susceptible to noise so, using a value of 1600 or more might give you a good exposure but the image may have a lot of digital noise as a result.

Small values like 100 and 200 should show little noise at all.

Image: ISO100 f/4.5 1/500s – in bright summer sunlight, the ISO 100 value reduces sensitivity to light still allowing for a fast shot.

Of course, even excessive amounts of noise are preferable to getting a blurred image because you couldn’t hold the camera steady long enough to take it.

While the Auto setting on your camera will ensure that you get a good photograph most of the time, for creative purposes being able to configure your camera to adjust either the aperture or the shutter speed will give you more and varied options for getting even better images.

Image: ISO 1600, f/5.6, 1/15s – At dusk in a NY street, the high ISO gives good light sensitivity and the slow shutter speed allows the cars in the background to be blurred nicely.

Helen Bradley

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posted by Helen Bradley @ 10:51 amNo Comments links to this post

Thursday, January 27th, 2011

Understand your cameras settings – Part 1 – Aperture

All digital SLRs and many point and shoots can operate in manual or semi-manual modes. If you capture most of your photos using Auto mode it’s time to look at some of the benefits you can get by switching to semi-manual operation.

With these modes you control the aperture or shutter speed and you get a chance to capture more creative photos. So how do you do this and what settings do you use? In this series, I’ll explain your camera’s Aperture Priority and Shutter Priority (Av and Tv) modes and also explain why your ISO setting  is important to understand too.

If your camera can operate in manual mode you’ll have settings such as M, Av, Tv and P on your camera’s dial. The two settings we’ll focus on are Av and Tv where you set the aperture or shutter speed yourself.

What is Aperture?

This begs the question, what is aperture and what is shutter speed? Aperture is, very simply, the size of the hole through which light enters your camera. The larger the hole, the more light gets in.

Aperture is described using an f number which is calculated using a complex formula. A rough rule of thumb is to think of aperture being a fraction so an f number (often called a f-stop) of f/2.8 is bigger than f/22 for example.

Understanding aperture

Aperture not only has a direct relationship to the amount of light let in to the camera, it also affects depth of field. When you use a large aperture such as f/2.8 you will get a small depth of field so only a small distance in front and behind the point of focus in the photograph will be in sharp focus and the remainder of the image will be out of focus.

Depth of field is a creative tool that many photographers use to their advantage. For example, when photographing a beautiful flower, you’ll want the focus to be on the flower and not the things behind it. Using a large aperture such as f/2.8 throws the background out of focus. The photograph at the top of this post is an example of a large aperture and a small depth of field.

On the other hand, using a small aperture such as f/8 or f/11 gives you a large depth of field so everything in the photograph will be in focus – useful when photographing landscapes for example.

The relationship between Aperture and Shutter speed

When you set the aperture using the Av setting on the camera, the camera sets the shutter speed to an appropriate value. This is because there is a direct correlation between aperture and shutter speed.

When you use a small aperture, only a small amount of light comes into the camera so you need to compensate for this by using a slow shutter speed to ensure you capture enough light.

On the flip side, when you use a large aperture such as f/2.8, you get lots of light so the camera will set a fast shutter speed.

When you use Av mode, you’re effectively saying, I’ll set the aperture I want and you – the camera – are to adjust the other settings to give me a good picture. When you are in Av mode, there will be a dial or other option you’ll use to set the desired aperture value.

Helen Bradley

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Wednesday, November 10th, 2010

Hyper-focal distance and DOF

I’ve been playing around this week with my new Pentax K-7 shooting a range of images to use to illustrate Depth of Field for an article I’m writing. I’ve also been drawing pictures to illustrate Hyper-focal distance – I love my job!

As I was trawling the web I found the DOF Master website which calculates all things hyper-focal and DOF.

There you can calculate the depth of field required for various situations – simply select your camera and the focal length of the lens that you are using. So, for example, if you have a 28 – 200 lens and are planning to shoot at 100 mm, then select 100 mm for the focal length. Select the f stop that you intend to shoot at at for that focal distance. Then select the distance between you and the subject and click Calculate.

So, for example, for my Pentax K7, shooting at 100 mm with f/5.6 at a subject 10 feet away, the depth of field is approximately .67 feet and the hyper-focal distance would be 290 feet.

If you’re using a fixed focal length lens, then there is also an online depth of field table available on that site. Select the focal length of your lens and the camera that you are using and click Calculate – you’ll get a printable table showing the near and far range of the depth of field at a given distance and aperture, as well as the hyper-focal distance. How cool is that?

Helen Bradley

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posted by Helen Bradley @ 1:02 pmNo Comments links to this post