Fast prime lenses offer a number of advantages. They are great tools in many situations – whether you need discretion, low-light performance, portability or aesthetics, there’s a lens for every taste. However, these strong advantages also come with certain issues. When used wide-open (meaning at maximum aperture), many prime lenses render extremely shallow depth of field. In normal lighting conditions modern AF systems are capable of focusing accurately. In low-light environments, our DSLRs start to suffer, which reduces our chances of capturing sharp images. Because of this, missed focus is often mistaken for lack of general lens sharpness by beginner photographers. In this article, I will introduce you to several tips on how to use fast lenses in low-light environments, which hopefully will make you feel a little more confident when using them for your photography needs.
Tips on Shooting in Low-Light Conditions
1) Calibrate Your Lenses
The first step you need to take in order to focus accurately in any light, is to make sure that your lens(es) can focus accurately in general. Front and back-focusing has become a very known issue recently. It has become especially visible with higher resolution sensors – they are most unforgiving if you miss focus even slightly.
Most modern, higher-end DSLRs offer a focus calibration function. This feature effectively saves you from having to send your lenses and cameras to a professional service or the manufacturer. It can also save you a lot of time. Fully calibrating your lenses to your camera may take you a couple of hours, while sending your gear could take up to a few weeks. If you’d prefer to automate the process as much as possible, there are a couple of software products you can use that will do that for you.
2) Use a Good Stance
Presumably, if you use a fast lens, you will have a fast enough shutter speed to counter hand shake. However, it is equally important to get into a stable, secure stance when shooting wide-open in low-light for critical focus accuracy. This is because a wide aperture results in a very thin depth of field, which, at a set focus distance, moves whenever you or your camera moves. In other words, if you sway an inch forward or backward once you’ve already focused, your subject will be out of focus by an inch. Mind you, we never really stand still – we move forward, backward and sideways all the time. The effect of such movement is very apparent with wide-aperture lenses. It is critical to remember this and learn to keep still when you focus and make an exposure.
A good way to keep still is to lean on a large stable object like a wall whenever possible. Also, keep your feet at least at shoulder width with one foot slightly in front of the other.
3) Refocus Constantly
Another tip to remember is to adjust for any body movement by constantly refocusing your lens. Whenever I shoot a moving subject in dark environments, I never really settle with my focus. I engage it almost all the time whilst I wait for that moment. In tricky, low-light environments, many AF systems will sometimes fail to acquire precise focus on the first try. Constantly refocusing allows me to make sure I get perfect focus when I finally take the photograph.
4) Use Cross-Type AF Sensors
Phase-detect autofocus systems have two kinds of focus points. The best ones are sensitive to both horizontal and vertical detail and are called cross-type sensors. The remaining ones are sensitive to just the horizontal or just the vertical detail. Cross-type sensors are much more dependable in low-light environments and for this reason it is preferable to use them. Usually, the center sensor, which is always cross-type, is the most reliable and accurate of the bunch.
5) Focus And Recompose Carefully
If you are indeed going to use the most reliable center focus sensor, remember all the issues you may be faced with. To get a good composition, you will first need to learn focus and recompose technique. And the technique comes with its own set of potential issues, such as focus plane shift (because the focus plane changes when you recompose the image). Also, it takes time to recompose.
With enough practice you may be able to learn how to use this technique with confidence in low-light. Each time you focus on your subject, imagine a thin wall in front of you, which represents depth of field. Everything in front and behind this wall is blurry / out of focus. The closer you are to the subject and the larger the aperture, the thinner the wall gets. So if you are too close to the subject and you are shooting at maximum aperture, your picture might not come out sharp when you focus and recompose. Hence, stepping back a little and not going too aggressive on the recomposing part is a good way to reduce the effect. Remember, this will take a lot of practice. But once you get a hang of it, it will come naturally when photographing in dark environments.
Lastly, always pick the brightest and the most textured area to focus on – your camera’s autofocus system needs plenty of contrast for good accuracy.
6) Experiment with Focus Settings
I have photographed a lot of low-light events during the last few years. What I’ve learned was that depending on lightning conditions and lenses used, different settings work best. In some cases, I prefer continuous AF tracking knowing I can trust it completely. Other situations demand single AF mode. I even use manual focus sometimes because AF can be so unreliable! So, definitely spend some time experimenting in low-light environments and photographing moving subjects. It will help you to know which settings work best when.
7) Turn On the Focus Assist Lamp
The focus assist lamp can be of huge help when it comes to focusing in low-light situations. Whenever you engage autofocus, AF assist will light up your subject providing more light to the scene. More light helps AF speed and accuracy greatly.
have someone point a flashlight at your face, and AF assist beam is in fact a small flashlight. Also, using your camera with AF assist beam turned on will drain your battery more quickly. The range is not that great. More importantly, it will only work with the center AF point in single autofocus mode.
If you’re a Nikon shooter, a modern Speedlight, such as the SB-910 will often be more reliable than the AF assist lamp and will not blind your subjects, because it fires a quick red beam instead. However, you will still be unable to use it in continuous AF mode.
8) Rack That Focus
Another useful tip that often works for me, is to rack the focus ring when the lens doesn’t seem to focus properly. Sometimes the lens fails to acquire good focus and yet the camera thinks otherwise. By racking the focus ring, you basically force the camera to re-engage its autofocus (since everything is too blurry), which might give you better results next time. Keep in mind that this will only work on more recent lenses that have an autofocus override. Some older lenses will not let you turn the focus ring in AF mode.
9) Shoot in Burst Mode
Shooting in low-light diminishes your chances of capturing technically adequate keepers. AF inaccuracies are one of the main reasons for this. Shooting in burst mode will help you increase the chances of taking a well-focused photograph. Naturally, you will have more images to sort through, but imagine the disappointment of having captured an amazing image with great composition and story that’s also badly out of focus. Also, in low-light environments, your timing is affected by the focus acquisition speed. Whether you choose to shoot at several frames per second or take extra images in the single servo mode, it’s a good idea to over-shoot just to make sure that you have images with correct focus and well-captured subjects.
10) Final Words
Some of these points are just as applicable in good light. Once you learn how to properly use your beloved prime lenses to achieve satisfying results, you may find them to be much better performers than you originally thought. As it is often said by photographers, it’s not the camera or lens that doesn’t deliver – it’s the person behind the camera.