Saturday, 25 August 2012

Depth of Field: Choosing the Right Focus Point

Most of the time, when we want to get everything in our shot in focus from our feet out to infinity, the tendency is to dial in as high an aperture number, or f/stop, as possible. In doing so, we hope to increase the depth of field in the image, or the range from our near in-focus point to our distant in-focus point.

But there are two other parameters that have a dramatic effect on depth of field: focus point and focal length of the lens. Two rules of thumb for increasing depth of field are

·         Manually focus as far away as you can from your subject while still keeping them in focus at the aperture you are using, and

·         Use as short a focal length as you can to compose the shot.

Take the second point. We’ve all seen wildlife and sports shots that are taken with a very long focal length lens. The subject is very sharp while the background and foreground are very much out of focus (shallow depth of field). So, conversely, using a short focal length (or wide angle setting) results in a deeper depth of field.

Choosing the focus point, however, is probably the most critical parameter in achieving the shot you want. The first point above implies that the further away from the camera that you focus, eventually you will have everything in focus from a point close to the camera out to the horizon (infinity). To put a label on it, when this happens, you are focused at the hyperfocal distance. This term is mostly of interest to landscape photographers but the point is that, counter-intuitively, we need to focus beyond our subject to get it and the background appearing sharp.

The best graphical demonstration of this is the Online Depth of Field Calculator at Choose your camera model, focal length, aperture and subject distance. Assuming you focus on your subject, the calculator tells you the near focus and distant focus points. The difference between these is the depth of field.

Hyperfocal distance is also illustrated. If you focused at this distance, everything would be in focus from the distance shown in the illustration out to the horizon. Note that sometimes hyperfocal distance won’t get your subject in focus because the near focus limit is further out than your subject. In this case, you would have to use a higher f/number, shorten your focal length or resign yourself to not having the horizon in perfect focus.

The following images were shot using highly sophisticated dollar store markers at 5 foot intervals. The closest was 5 feet from the camera’s sensor. The camera was a Canon Digital Rebel using a fixed focal length of 35mm in all examples. Each image has been cropped from the originals.

In the first image, aperture was set to f/22 and focus was manually set to the calculated hyperfocal distance of 9.5 feet (just in front of the second marker).  Notice that the 5 foot marker is still in focus, as well as the tree top a couple of  hundred feet away (See insert). This is because the near focus limit is calculated to be 4.7 feet. (Note that the insert looks a little soft because the sensor resolution is starting to come into play.)

The second image was also at f/22, but the camera was now focused at our subject, the 5 foot marker. The calculator tells us that if we focus at 5 feet rather than the hyperfocal distance, our focus range now covers 3.3 feet to 7.2 feet. So our depth of field has now decreased from infinite to 3.9 feet just by focusing at 5 feet rather than 9.5 feet from the camera. Note that the markers at 10 feet and beyond are a little softer, and the tree top is no longer in focus (slightly softer).


At f/10, our next image was focused at the calculated hyperfocal distance of 21.1 feet (just past the lowest 'lollipop'). The near focus limit is calculated at 10.5 feet, and indeed the second marker at 10 feet is very slightly soft. The tree top, while not perfectly sharp, is close to being in focus. I chalk this discrepancy up to difficulty in getting the focus exactly at 21.1 feet. Note that our subject at 5 feet is badly out of focus, so f/10 is clearly not a good choice if we want focus from 5 feet to the horizon.

Still at f/10 in the last image, the subject at 5 feet was once again our focus point. Calculated near and far focus limits are 4.1 feet and 6.5 feet, giving a depth of field of only 2.4 feet.


The conclusion? Decide whether you want to shoot like a landscape photographer or whether a little bit of in-focus background will suffice for your shot. Even if you don’t use hyperfocal distance, the calculator will help you choose a manual focus point beyond your subject that will keep it in focus but still give you a decent background focus.

Wednesday, 22 August 2012

Extending Summer, Photographically

At this time of year, most of us are in denial that the long days, warm evenings and cricket sounds at night are soon going to fade into the cool of autumn.  While the change is inevitable, it’s nice to capture that summer feeling in our art and keep it in our walls year 'round. 
For me, the image shown here (Far and Away) brings on the warmth and color of the midsummer evening. This was shot with a long lens trained on a small island in Lake Erie. The trees almost seem to float above the water because the surface of the lake was calm around the island's shore.  A light ripple from the evening breeze creates a cyan reflection of the sky in the water in between, while the inshore water calms again and reflects the alpenglow-like color above the horizon. 
Swallows were constantly swooping over the lake surface, seeking mosquitoes for the evening meal. Waiting for them to get out of the frame required a bit of patience, but their presence was welcome nonetheless.  
To help visitors to my web site extend their summer by putting such scenes on their walls, I am offering a 20% discount until the end of September 2012.
Please go to and simply use Discount Code PKGNDY at checkout. The discount can be used for any image on the web site.

Sunday, 5 August 2012

The Photographer’s Workflow: Organizing your Images

Unlike the 35mm film days, we don’t think twice about taking reams of shots with our digital cameras. We’re only limited by the amount of camera memory we have. But what do we do with this plethora of photos? Organizing them into genres or collections of similar photos would help us find a particular image....maybe. Wouldn’t it be nice to type a word into an application and have all of the shots that pertain to it pop up on your computer? I have two words for you: keywording and Lightroom®.

For most of us, our image files end up in a big, ugly clump on our hard drive. Now, we have the task of deleting the junk and deciding from the remainder which ones are ‘maybes’ and which are keepers. I know - it’s difficult to make those decisions, and I can’t help you with that. But, once you whittle the pile down, you can start to organize it.

So what is a photographer’s workflow? Simply, this refers to what happens to your images between the moment you download them from camera to computer and the time you prepare them for email, website posting or printing.

Let’s back up to that first step: downloading from the camera. I use the utility software supplied on CD  by the camera manufacturer because it can automatically read each image’s metadata and store that image into a folder named with the date the shot was taken. At least now, we have some semblance of organization, but it’s only the beginning!

Enter Lightroom®, a software package from Adobe. For the purposes of this blog post, I am going to assume that the reader is not a power Photoshop® user, and that the image adjustment tools in Lightroom® are more than sufficient for tweaking the camera images. The workflow might go something like this:

1.       Import the ‘keeper’ image files into Lightroom®. These can be in a number of different formats, including RAW files. You may wish to import them into the default Catalog or create your own before importing. The Catalog stores all information about the images you import into it, including all changes you make, so they can be recalled later and undone step-by-step if you wish. The important thing to understand is that Lightroom® does not actually create a copy of the image when importing it, but rather stores only the location of the original file plus all changes you’ve made to it without changing the original.  In other words, it temporarily pulls in a virtual copy of your image and saves the changes you’ve made to it in the Catalog. The resultant Catalog file is much, much smaller than the total of all the original image sizes.

2.       Create keywords in the Library module for each image. There are two compelling reasons for  doing this:

a.       You can use Lightroom®’s search function to find all images that contain those keywords.

b.      If you sell prints or stock photos online, nobody will find your images unless you keyword profusely.

Within a Catalog, Lightroom® builds a keyword list from all the keywords you add to all the images in that Catalog. As you import new images into the Catalog, it gets easier to keyword them because you now have a list of keywords you can choose from.

What words should you use? Put yourself in the place of someone searching online for a photo like yours. Think of every word you might use in a search string. Include location, objects in the scene, weather conditions, season, genre (ie. Nature, people, architecture) and even the image orientation (portrait, landscape). Cover every possibility – the more words, the better the chance of being found.

3.       Tweak the images for best quality in the Develop module. While not supplying all the capabilities of Photoshop®, Lightroom® has an impressive array of tools to correct exposure, white balance, sharpness and noise. Other tools, such as split toning, allow some impressive creative adjustments to be made. If you’re not feeling particularly daring, you can select from a wide variety of special black and white or colour presets to give your image a different look. If you want to save various versions of the same image with different visual effects, you can create as many virtual copies of the same image as you like and apply different changes to each. The good news is that the keywords also get copied over to each virtual copy. This is probably the best reason to do your keywording before starting your image tweaking.

4.       Do something with your final images. I upload images to various sites for licensing stock images or selling prints on demand, so I like to Export jpeg files from Lightroom to a separate folder on my hard drive. Now I’ve created images that take up space on the drive, which may seem to work against the concept of using Lightroom®'s space-saving virtual copies, but sometimes it’s necessary. Otherwise, if you simply want to print what you’ve created in Lightroom®, you can go straight to the Print module without exporting a file. Or, if the website you use allows it, you can use the Web module to upload keyworded and tweaked images without increasing the footprint on your hard drive.

Once you’ve done all you’re going to do to an image, you can also create Collections within a Catalog. This allows you to store a virtual copy of a photo in a group of similar photos. For example, you may create separate collections for your Nature, Family and Travel photos. Just another way for you to find a photo if a keyword search isn’t helpful.