Knowledge Base

Buying Telephoto Lenses

A beautiful golden sun was setting across an equally beautiful sea, its azure colour a reflection of the heavens. The purple tint of cirrus high in the atmosphere contributed to a scene unashamedly cliched, but irresistible to photograph. Stepping back several meters, I added an unspoilt golden beach to the composition. Good enough to release the shutter? Yes, but it could be better; walking slowly along the beach were a young couple. Arm in arm, they were lost in the moment and each other. I paused, allowing them to walk into my scene, now an exercise in sunset contre-jour and blissful romanticism. The decisive moment had arrived, and I committed to celluloid a beautiful moment that faded with the setting sun.

The above is based on some diary notes, my memory, and an image that is now more than 35 years old, taken on a Tunisian Beach during my first ever trip overseas. It was December and a bitterly cold one in the UK at that. The weather could not have been more different to what I was experiencing on my twee North African adventure. This photograph, along with many others taken during the week, proved to be the catalyst for my pursuit of photography. Of course, I did not see any of the results until a week or so after the trip ended – this was way before the digital age. But the excitement began with the composition, having the building blocks of a good photograph in front of me. All I had to do was... well, compose. The anticipation waiting for my results to return from the lab added fuel to an already excited 21-year-old. Reviewing the photo’s revealed a mix of hits and misses, but little that disappointed at that time. It provided me with a pictorial manual that I studied time and time again in an effort to improve technique.

I had just two lenses for my SLR at the time; a 50mm f2 standard and 135mm f3.5 short telephoto. Referring back to the sunset image, either would have made a respectable job of the scene, albeit with differing interpretation. I chose to use a telephoto lens for the simple reason of getting a larger sun in the frame. What I did not realise was how its use contributed to the final scene when the young couple walked into it. The compressed perspective brought the suns orb closer to them. The sea revealed a little more drama. The lovers, no longer a detail, became the focal point. Simply put, this short telephoto added drama and emotion that would have been greatly reduced had I pushed the scene away from me by using the 50mm.

It was this photograph that revealed to me some of the more intangible aspects of telephoto attributes that became something of an obsession for many years.

The telephoto lens group is as equally large as its intended subject matter and, to my chagrin, one that I spent a lot of money exploring without having an intended target. I was more interested in how a specific magnification affected an image… its strengths and weaknesses. Over the next few years I found myself with a collection of telephotos much too large to carry around and too plentiful to allow quick selection. While I gained an understanding of what was possible with them, and situations I could best use them in, my results did not improve at the pace I would have liked. Not having a specific subject i.e. wildlife or sport meant that I did not settle on a favourite focal length for many years. Instead I drifted where curiosity took me before realising that my journey had, more or less, ended where it started… at around 135mm.

So, what has my telephoto voyage of discovery taught me? Below, rather belatedly, are some of the points I would consider when dipping my toe into the realm for the first time.

  • Consider your Subject

    Consider your subject matter carefully; this will go a long way to reducing your cost and avoid building up a bunch of lenses that seldom get used or taken out on the field. If your intended subject is bird photography, you are going to need something with an extreme reach, particularly if you are wishing to capture close up images of smaller species. A focal length of less than 400mm is not likely to give the desired results unless you intend to include some of the environment. If you wish to keep cost down a little and provide some flexibility, contemplate adding a high quality teleconverter. Usually available as 2x or 1.4x variants, remember to factor in the inevitable reduction in f-stop values as this may make the lens too slow to be of any practical use.

  • Aperture

    A vitally important element of any telephoto lens purchase. Speed adds significantly to the cost, weight and size so if you really think you don’t need it, look for something with a more modest aperture. On more than one occasion I have been lured by speed only to find that, once the honeymoon period is over, I leave the lens at home due to its incumbent weight. A fast lens is important for some sport and wildlife subjects as the key to success can be partially attributed to freezing the moment. Low light photography, such as theatre or concert work will also greatly benefit.

  • Zoom or Prime

    The eternal debate that affects all lens groups is whether a zoom or prime lens will be better. Zooms rarely come in extreme telephoto lengths, so if your subject matter demands e.g, 800mm, the chances are the decision will have been made for you, and a prime is the only offering. If, however, your demands require something much less in terms of power (and like me, for much more general use), the versatility of a high-quality zoom is worth considering. Not only will it reduce weight and bulk but provide a great deal of flexibility. The key phrase in the above sentence is ‘high-quality’; speaking from experience I cannot emphasise this enough. Having made a couple of poor choices in the past, I moved away completely from zoom telephotos in favour of a bag full of primes. It is only in the last few months that I have revisited the design and sought out a model that above all attributes is of a very high-quality design and build. It comes at the expense of a fast aperture, but the results are of a calibre I have never personally experienced before in a telephoto zoom. For my requirements its 80-200mm range meets my own demands perfectly and, for the first time in decades, means that I can carry all of my telephoto options with me at all times – so goodbye to the closet queens!

  • Weatherproofing

    If you find yourself outdoors in challenging conditions, some kind of environmental sealing should probably be considered as pre-requisite, especially if your camera body is built to such specifications. After all, what use is a sealed body if the lens is not? Most manufacturers offer this technology in their lens line ups, albeit it may only be found in more expensive ‘professional’ grade models. Do not over estimate the importance of this if you do find yourself photographing outdoors in harsh conditions.  Such conditions are not limited to rain and snow; consider also the impact of wind, dust, sand and humidity – all can have disastrous consequences for gear that is not suitably protected. A high quality protective filter should also be deployed to ensure the front element is not unnecessarily exposed.

  • Image Stabilisation

    Before the days of image stabilisation, photographers had to rely on a tripod or other form of support to ensure sharp images. The magnification of telephoto lenses causes image movement to be exaggerated, resulting in the possibility of camera shake being introduced into images. In situations where a fast shutter speed is not possible, this will reveal itself as blur in the final image. As an overall rule of thumb when hand holding a telephoto lens, a shutter speed higher than the telephoto focal length should be used to mitigate the problem e.g. 200mm = 1/250th second, 400mm = 1/500th second.

    Image stabilisation whether engineered into the camera lens or body will reduce this constraint allowing sharp, hand held results at reduced shutter speeds. Its benefit to telephoto lenses should not be underestimated and it is in this lens group that the benefits are best demonstrated. If your camera body is image stabilised, any lens attached will benefit. If it is not, factor it in to a potential lens purchase.

    Bear in mind that if a tripod is used, image stabilisation should be switched off as it can detract from sharp images. I personally tested this several years ago and there was obvious degradation in the results. This is due to stabilisation being designed to look for and counteract motion. By no means are all lens/camera manufactures affected, but if in any doubt check this out with the manufacturer.

  • Short Telephotos

    By far my favourite telephotos are those with a focal length between 80 and 135mm. They are extremely versatile, can be used for general day to day shooting and lend gentle perspective compression to results. Subject matter includes portrait, candid and landscapes with fast aperture variants producing beautiful 3D effects when used wide open. Some also provide macro focussing abilities, effectively extending their use into a completely different realm. Many are also very portable, taking up little in the way of bag space while being fairly lightweight. For those times when I do not require a telephoto zoom, I opt for my 90mm f2.8 due to its higher speed and macro capability.

  • APO Glass

    One of the main aberrations exhibited by telephoto lenses (along with others) is colour fringing, caused by an optical inability to focus light wavelengths precisely at the same point on the image plane. For example, red focuses at a different wavelength to green, causing colour fringing that is more noticeable in high contrast areas. The problem is amplified as the lens’ focal length increases, requiring optical correction to reduce or illuminate the problem.

    Typically, this is addressed by combining lens elements with low dispersion properties which accurately focus primary wavelengths (red, green & blue) resulting in a sharper image with little or no colour fringing.

    The term ‘APO style’ should not be confused with true ‘APO’ technology. The former is marketing speak for a lens that has been corrected similarly (typically focussing two primary colours, not three – therefore achromatic, not apochromatic in design). Correcting two primary colours is less expensive and can, in well designed models, provide excellent results. I once owned a 300mm lens that was achromatic which produced superb results with very little colour fringing.

    I currently own two true apochromats that, after careful testing at wide apertures on high contrast scenes demonstrate perfectly what APO glass is capable of.

I am sure there are many more points to consider that seasoned telephoto users will be quick to point out. Not being a photographer dedicated to this realm, my own knowledge remains limited even after more than three decades. What my journey has taught me is;

  • I do not have much of a requirement for focal lengths beyond 200mm
  • Zooms now produce results equally as good as some of the primes I have used
  • ‘Long Toms’ are darned heavy – more than a couple caused me to start leaving gear at home
  • A well corrected example is expensive, but worth paying for
  • I love the shallow depth of field a fast short telephoto provides

Referring back to the opening paragraphs of this article, I wonder what happened to the couple that featured in my picture? Like my composition there were perhaps many possibilities. And like most of life’s journey, choosing the correct path is something of an unknown.