Troubleshooting your photography – Portrait focus
Today I start a new weekly series called Troubleshooting your Photography. This series is geared towards beginning and intermediate photographers, but old grizzled photographers (yours truly included) may also find useful tidbits in these musings. Watch for new articles each Tuesday. Are you new to photography and finding that people on social media are not liking your images as much as you expected them to? I view many online forums geared towards photography and see many common mistakes that can be easily resolved. Each week I will cover a specific topic in the hopes that these articles can help budding photographers today and in the future.
We all want nice blurry backgrounds for our portrait shots, but there are a couple errors that can cause those portraits to be out of focus. The most common portrait error is not getting the eye of the model in focus. We instinctually look at the eyes first when looking at another person, therefore in a portrait, this is the first thing a critique will ding you on if the eye is not in focus. First, to ensure the eye(s) are in focus, choose a smaller number of autofocus points (check your camera manual for instructions on doing this.). I generally use a single or close clustered focus area when shooting a portrait. Many cameras will also allow you to turn on the focus points when reviewing an image. This is especially helpful to me, as I have a hard time seeing the focus points when looking through the viewfinder. Once you have your focus points nailed down, consider the aperture you are shooting at and the distance to your subject as the next likely culprit to a poorly focused shot. When shooting at a wide-open aperture like f2.8, and using a smaller number of focal points, many photographers will focus on the eye, then recompose or reframe the image. During this moment, the thin focal plane of a f2.8 or smaller aperture can easily throw most of the face out of focus if the photographer or model move forward or back even slightly. Practice getting the eye focus and then quickly moving to recompose your shot to minimize this issue.
Another consideration when shooting portraits is: do you need to have your background blurred? If you are shooting a model close to a background like bricks on the side of a building or a flat white wall, there is likely not enough room for the aperture to blur the background sufficiently, therefore a middle of the road aperture might work well and have more of the model’s face in focus. An aperture of f8 will be more forgiving for a learning photographer than a larger one like f2.8. Basically, just because you have a lens that will go to f2.8 or f1.4, doesn’t mean you have to shoot at that aperture all the time (shooting at the larger apertures can also result in softer images as we will see later.). Many beginning photographers think they need to start with a wide-open aperture, consider your shooting situation before choosing a setting. You can also try shooting in aperture priority mode (AV) and easily switch to a few different apertures during your shoot.
Focus or fail
The majority of images posted from new photographers have one thing in common, – lack of proper focus. Most of the DSLRs (and mirrorless cameras) on the market have well over 30 autofocus points. When you look through the viewfinder and see all those little dots on your subject, it looks like your image will be in focus. The frustration comes when you post that image online and the first comment you see is “the image is soft” or “you missed focus on the eye”. So, what went wrong? Why isn’t your image in focus? Let’s break it down piece by piece for a closer look.
Aperture is one factor
Many problems arise from those shooting with a lens that has a very large aperture like f2.8 or f1.4. Images shot with a larger aperture will have a nicely blurred background (called Bokeh) while this is a very pleasing look, be aware that a larger aperture value decreases the focal plane – the focal plane is the area forward and back from the location you focused on. The smaller the aperture (the larger aperture number you use), the larger the focal plane will be, and as a result, more of your subject and background will be in focus. Considering a portrait of my mannequin Megan as our example here, if you focused on the model’s eye and took a photo, you could expect just the eye to be in focus if you used a larger aperture like f2.8, and more of the model and background in focus using f8. For my sample images I used a Canon 5dmkiv camera and a single Profoto D2 strobe in TTL mode. I shot in aperture priority with my ISO set at 100, which left the camera and strobe to sort out what shutter speed to use for proper exposure. I didn’t spend any time post-processing the images, since I thought it would be interesting for you all to see how the images changed when limited variables were involved (camera setting shutter and strobe setting power). The lens I used was the Canon 70-200mm f2.8 IS II L. I didn’t move the model or the strobe, only the camera location from minimum focusing distance to the middle of the room and the farthest side of the room. Note: I don’t consider these final portraits by any means, since I didn’t take time to brush the mannequin’s hair and do any post-processing.
In example one, at minimum focusing distance for the lens, using f2.8, you can see that the forward eye is in focus, and the back eye is not. Also notice that her earring is not in focus, illustrating that the focal plane is very thin.
In the second example, using f8 still at minimum focusing distance, you could expect to have the model’s eye as well as his/her hair and chin in focus. Notice that the earring is more in focus, but not completely. Also notice the difference in the texture in the background material between the two images.
Example three brings the camera to the middle of the room. Look at the earring in this shot, it is much more in focus than in example one at the same aperture. The focal plane is getting larger and encompassing more of the model’s face.
Example four, also from the middle of the room and using f8 shows the earring and the eye in fair focus.
Example five, moves the camera to about 15 feet from the subject. Notice how much more the earring is in focus compared to examples one and three.
Example six is where most glamour and portrait photography is done, about 15 feet with a telephoto lens.
Thickness of the focal plane is a subject many don’t discuss. When you are learning about aperture and its effect on your images, the generalization is that larger apertures like f2.8 give blurry backgrounds and smaller apertures like f11 makes everything in focus. As you can see from our examples here, that is not really the case, as focal distance as well as aperture play a significant part in the amount of your image that is in focus. This was a point of confusion for me for quite some time, and I am surprised there are few articles on the subject. Anyone who has gone out to the garden to shoot spring flowers will know this very well. A flower shot at f4 from minimum focal distance will have less of the flower in focus than one shot at f4, but from a few feet away.
The sweet spot
There is another factor which can cause an image to be soft, and that is not using the sweet spot for your lens. There are several calculations to determine which aperture will give you the sharpest image, but there is none that are as precise as your eyes. There can be variations in sharpness from camera body and lens to lens. You need to do some test shots to determine which aperture is best for your setup (be aware that you can of course send in your camera body and lens to the manufacturer for calibration.). As a rule, the sharpest images you will get should be at a couple stop above wide open. This means that a lens that has f4 as the wide-open aperture, a setting of f8 will give you the sharpest results overall. Set up your camera on a tripod, focus on a subject at wide open, say f2.8 and then try some test shots at a few stops up – f4, 5.6 and 8. Review these images at 1:1 to determine which aperture yields the sharpest image for your setup. Remember that this is a generality, especially applicable to lower cost lenses. There are certainly lenses available which have excellent sharpness through its focal range like the Canon 70-200mm f2.8 IS L II lens.
For those looking for more scientific data for lens sharpness, check out the fine folks at DXO, they have an amazing database of almost every lens available. This link will get you to the review page, from there click the explore database link in the upper right of the page. It is possible to compare many attributes for lenses in general or even mounted on a specific camera body.
Is it all lost?
We all have images that are soft, or where we missed focus. Are these shots just trash? Well it depends. Depending on the nature of your blur, whether it is camera shake or movement blur there are some new features in Photoshop that could potentially bring a until now useless image back from the grave so to speak. I will direct you to YouTube for tutorials on shake and blur reduction, if your image falls into the category that Photoshop can solve then it’s a pretty miraculous tool. Note: this is only available on the newer versions of Photoshop.
Now that we have the basics of shooting at wide-open apertures under our belt, we will cover smaller apertures and some techniques for getting better focus in landscape and macro images next week.