We explain how fast lenses can benefit your photography and point out some great models in the X Series range
So, you’re thinking about investing in a fast lens for your X Series camera. That’s great. You’ll definitely notice big differences in the types of pictures you can make. If you’re still wavering, then you’ve come to the right place.
What is a fast lens?
Firstly, let’s recap on what ‘fast lenses’ are. The name is somewhat subjective and unspecific, but they can generally achieve a wide maximum aperture in relation to focal length. In that way, ‘fast’ lenses can let in more light than ‘slow’ ones.
What do we mean by a wide aperture? That’s where things get a little less clear, as what is considered wide varies between models. For example, fast lenses can be primes or zooms, but the widest aperture on a zoom will almost always be smaller than on a prime. So, while a 35mm F1.4 lens is seen as fast, so is a 16-55mm F2.8, even though the maximum aperture is smaller. Conversely, despite having the same maximum aperture, a 35mm F2.8 lens might not be considered fast, particularly as there are options that let in more light.
For zooms, being considered ‘fast’ is often more about offering the same maximum aperture setting throughout the focal range. But there are still grey areas. A 16-80mm F4 lens fits that bill, but wouldn’t necessarily be considered ‘fast’, as the previously mentioned 16-55mm F2.8 offers a stop more light. Zooms that see the maximum aperture fall as the focal length increases – dropping from F3.5 to F5.6, for instance – are definitely not considered ‘fast’.
Why use fast lenses?
What’s much more clearly defined are the benefits of fast lenses – and they’re exceptionally useful. Below, we’ve outlined each of them in turn and how they apply across all sorts of different photographic disciplines, from portraiture and landscaping, to sports and documentary.
More light means easier exposures
The larger the aperture, the more light can be recorded during an exposure. Therefore, fast lenses – whether zooms or primes – allow comparatively higher shutter speeds. Say you’re shooting with a 35mm F1.4 lens, and at the same focal length on a ‘slow’ zoom with a setting of F4. The fast prime will record three stops more light, so the shutter speed could be 1/250 sec instead of 1/30 sec. Or you could use an ISO of 200 instead of 1600.
What that allows is the ability to freeze subject movement and offset camera shake, both of which can lead to sharper images. Combine a fast lens with higher ISO settings and it also means you can continue to work handheld in low-light conditions, where you might otherwise need a tripod. Add the tripod, and you can even shoot very low-light scenes, such as starry skies.
Although the primary concern of a lens’s aperture is to let more or less light into the camera, maybe the most obvious draw of fast lenses is their ability to give a shallow depth-of-field. Using settings like F1.0, F1.2 or F1.4 on prime lenses can allow superb subject separation. So, models that can open up that much are regularly used by pro portrait and wedding photographers, as well as documentary and still life. It’s the same with apertures like F2.8 on a zoom lens, where users can pick out sports, action, and wildlife subjects with greater clarity, against often confusing or cluttered backgrounds.
As we’ve already mentioned, fast lenses allow more light into the camera, which is also a benefit when focusing. When locking on to the subject, a lens uses its widest setting, even if the exposure is set to a smaller aperture than that. The greater amount of light this gives means focusing is faster and, in some cases, more accurate, so the camera is less likely to hunt, especially in low-light conditions.
Adding lenses with wider apertures to your kit also means they’re easier to use with teleconverters. For instance, fit the XF1.4X TC WR to an XF50-140mmF2.8 R LM OIS WR lens, and as well as extending the focal range, you’ll lose a stop of light as usual. This makes it an effective 70-196mm F4 lens – but that’s still OK for sports and action, as well as fast focusing.
There are drawbacks to fast lenses, but ultimately, they’re minor and manageable. For starters, even though FUJIFILM X Series lenses are designed to be as portable as possible, the larger the maximum aperture, the bigger and heavier a lens is likely to be, compared to a similar focal length with a smaller maximum aperture. Also, very fast lenses won’t tend to close down as much as slower models – for instance, an F1.4 lens’s minimum aperture is likely to be F16, rather than F22 or F32, so you’ll have less control at that end of the scale.
If you’re going to use your new fast lens wide open, you’ll also need to choose your focus mode and point more carefully, as depth-of-field will be reduced compared to smaller apertures. To make the most of the widest settings in very bright light, a neutral density filter is a good idea, or use your camera’s electronic shutter – to push beyond the maximum mechanical speed. This is because the aperture lets in so much light, the shutter speed and ISO can’t shift far enough to compensate.
Pick your fast lens
There are plenty of great fast lenses in the X Series range, covering all focal lengths – from ultra wide-angle to long telephoto. And with zooms and primes, you can pick what best suits your style and subjects. Here are some to consider.
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