What lens should you buy? There are a number of factors to consider when you choose the best lens for your camera. Here’s what you should consider when looking for a new optic.
Buying a new lens is no small purchase, so don’t go making any ill-informed choices. In this quick guide we tell you the key features to look for when buying a lens for your camera – and even the accessories you should expect to come with it.
What is lens ‘speed’?
Aside from sharpness, a lens’s speed is the key thing to consider. But what is lens speed?
‘Fast’ lenses are those that have wide maximum apertures – f/2.8, f/1.8 etc. For example, the new Nikon 105mm f/1.4E has a fast aperture at a long focal length, meaning it will let in more light and allow one to shoot at faster shutter speeds.
The downside of fast lenses? They’re heavier and more expensive. The Nikon 105mm f/1.4E price tag starts at more than $2,000!
‘Slower’ lenses are cheaper, but you lose that flexibility. Quite often you will find yourself having to increase your camera’s ISO in order to achieve fast-enough shutter speeds in low light conditions.
What’s more, the speed of a lens is also relative to its focal length – a 500mm f/4.5 lens is actually a pretty fast lens, while a 100mm f/4.5 is rather slow.
What is minimum focus?
By minimum focus we mean how close you can physically get with your lens before it cannot focus on the subject at all. When this happens your lens has reached its near focus limit.
Minimum focus becomes a really important feature to consider when choosing a telephoto lens. It’s easy to be wowed by huge focal lengths and massive magnification, but if you can’t get close enough to take advantage of it, what good is it serving you? You’ll find you’ll need to use extension tubes to get closer.
What is floating vs fixed aperture?
There’s a lot of jargon in photography. It’s one of the things that satisfies our inner geek, but it’s also one of the things that can make people feel daunted early on in their photographic journey. A fixed aperture is a zoom lens that maintains the same aperture throughout the zoom range.
A floating aperture is simply a zoom lens designed so that the aperture gets smaller as you zoom from the wide to telephoto end of the focal range.
Needless to say, fixed aperture lenses are more expensive than floating aperture lenses.
The downside of a floating aperture (such as f/4.5-5.6) is that, in order to maintain the same exposure, you must use slower shutter speeds as the aperture gets smaller. So you constantly need to be aware of possible camera shake creeping in.
Online shopping is a wonderful convenience, but it’s only by testing a lens in a physical camera shop or by reading reviews (hopefully Camera Jabber reviews!) that you’ll know if a lens’s image quality will meet your needs. We all know how important sharpness is, but don’t forget to other important lens qualities, such as its ability to handle flare, vignetting and optical aberrations.
A lot of this comes down to the type of glass used in the lens’s construction. We often see those odd abbreviations in lens names and think they’re unnecessarily complexly titled, but most of those letters such as APO, L, ED, ASP that you see after the focal length aren’t just marketing gibberish – they do actually tell you if better glass has been used.
It sounds ridiculous given that you hold your camera, not the lens. But how a lens feels in your hands shouldn’t be discounted. Again, you’ll need to visit a camera shop and ask to mount one.
Do the zoom and focus rings fall in the right place for your fingers? Can you reach the image stabilisation switch easily? These are important considerations.
Type of zoom
You’ll find there are two types of zoom lens – the common ring type, or the now less common push/pull ‘trombone’ style design. The push/pull lenses are simpler to use, however longer versions can become a bit awkward to handle when zoomed all the way to the telephoto end of the focal range.
What is a rotating filter ring?
Budget lenses often feature a front element that rotates as the lens focuses. What’s wrong with that? you may be thinking. Nothing in principle. Except when you’re using filters. If you shoot a lot of landscape photography and use a polariser or graduated neutral density filter, in particular, this is something to consider.
With a polariser mounted, a rotating filter ring will change the look of the effect as it turns. However, there is a simple workaround: focus first before making filter adjustments.
What is distance scale?
Distance scale is handy for determining depth of field. Again, this should be a concern for landscape photographers who want to maximise sharpness throughout the frame. Many modern lenses don’t have one though. And, really, we don’t know why!
A lens hood is essential for helping to reduce flare. Most new lenses come with one, however not all do. If the lens you want to buy doesn’t come with one… factor the extra cost. It’s essential. The same is true for a tripod collar for larger lenses.