How to choose a zoom lens
Buying a zoom lens is not an easy task. There are many factors to consider such as how long the lens needs to be, how fast it needs to be, what it is going to be used for and the amount of money you are prepared to spend, This article provides advice and tips on buying a zoom lens.
So, how do I choose a zoom lens?
When deciding on a zoom lens the first thing to consider is the minimum, and maximum, focal lengths the lens is to cover. For example, it is possible to buy wide angle zoom lenses that have a focal length of 10mm – 20mm, such as Canon’s excellent EF 10mm – 20mm f/3.5-4.5 USM, or a super tele lens with a focal length of 50mm – 500mm, such as the Sigma 50mm – 500mm f/4.5-6.3 DG OS HSM. Despite both of these lenses being zoom lenses, each one is used for a different type of photography. The Canon is most likely to be used for wide angle panoramic landscape shots, whereas the Sigma is likely to be used for shots of wild birds or motor shots, or any other type of close up shots where it is not possible to get close to the subject. Therefore, if your primary interest is in landscapes the Sigma would not be the best option, similarly if your interest lies in wildlife the Canon doesn’t have the reach needed to get close up shots of animals.
The Canon and Sigma above represent the extremes and, fortunately, there are many zoom lenses in between these focal lengths available to the photographer. Such sizes include the 70mm – 200mm, which is available from most lens manufacturers all of whom claim it to cover the most ‘useful’ focal lengths, 75mm – 300mm, 100mm – 400mm and 50mm – 150mm to name but a few. All buyers should identify the most suitable focal lengths for their interest and start from that base.
Once the zoom length has been identified, the next thing to consider is the speed of the lens or the ‘F’ number. The lens speed required will once again depend on the type of photography. Landscape shots are often done using a small F number, i.e. a slow lens, in order to get everything in focus, whereas indoor sports photography often need a fast lens to get a useable shutter speed in restricted light. If most of your shots are done outside in natural daylight it is possible to buy a higher ‘f’ number, i.e. slower lens, and an F4 is a good choice. If most of your shots are done indoors or in poor light then a lower ‘f’ number, i.e. faster lens, is needed such as an F1.4 or F1.8. In addition to the light you also need to consider whether most of your shots are done handheld or with the assistance of a tripod or monopod. When taking handholding shots a faster shutter speed is required, to minimize blurring caused by camera shake, and a fast lens is needed. However, when using a tripod or monopod slower shutter speeds can be used, therefore there is no need to have a fast lens, even if shooting indoors or in poorer light.
Now the required zoom and speed has been selected it is a matter of looking for a lens that contains everything you require, although this is easier said than done. Fast long lenses are very expenses and compromises often have to be made, unless there is an endless supply of cash that is.
Arguably, the most expensive lenses are made by Canon, Nikon however these lenses often contain professional grade optics that are capable of producing stunning images. Before parting with the money for these lenses you really have to ask yourself the question “Do I need professional looking shots?”
Obviously it would be nice to have a bag full of professional lenses, but given the expense few amateur photographers are likely to achieve this. Besides, most amateurs don’t really need such extravagant lenses. Fortunately, there are cheaper alternatives out there and third party manufacturers such as Sigma, Tamron and Tokina produce some very good lenses that are capable of some very, very good images, most of which will be more than good enough for all but the pickiest of amateur photographers.
Before deciding what zoom lens to buy, scour the internet for reviews from owners and see what the advantages and disadvantages of each are. In addition, join a photography forum (there are many out there) and post a thread. Most photographers will be only too pleased to offer advice and assistance. When reading reviews and posting threads you need to keep an open mind and look at them objectively. It is likely you will find both good and bad reviews for each lens so these need to be weighed up.
If possible, borrow a copy of each of the lenses you are interested in and take some shots. If it is not possible to borrow the lenses rent them, whilst this is obviously more expensive renting could save you a fortune in the end. When using the lens don’t just look at the images but think about the weight, how easy it is to use, what it feels like on the camera etc. etc. All things need to be considered in order to make an informed choice. Never go with a lens because that is the ‘fashionable’ one to have.
Buying a zoom lens can be a painstaking task and you are well advised to spend some time researching and testing before making the final decision.