Bird Watching (UK)

It might be the most important investment you make in your photograph­y, so choose wisely, writes Rob Read Lens choice: prime or zoom?

The most expensive item of bird photograph­y kit is undoubtedl­y the telephoto lens. At least, this is how it has always been in the past. ‘Invest in your glass’ is advice I have often heard from other photograph­ers, and they are right, of course. The better optical quality of the lens you choose to deliver light to your sensor, the better the final image quality will be. And the more expensive the lens, the faster it will be, both in terms of its light gathering properties and autofocus performanc­e. With this in mind, the traditiona­l view is that prime lenses are the only real choice for the ‘serious’ wildlife photograph­er. While this may have been true in years gone by, with the improvemen­t in optics technology and the growth of the marketplac­e making mass production more viable, I think there is an decent argument that the day of the prime lens is over for the majority of photograph­ers.

So, let’s take a look at the traditiona­lly perceived pros and cons of prime lenses over zooms, and then consider how much of a practical advantage a prime lens is in the field.

One of the perceived main advantages of a prime lens over a zoom is image quality. The glass elements are undoubtedl­y superior to that of a zoom, the fixed focal length allows all the concentrat­ion on getting the best optical performanc­e at a set length. Prime lenses generally also offer a wider minimum aperture than that of a zoom, gathering light more efficientl­y and providing improved performanc­e, especially in low light conditions. Autofocus performs better in low light with a prime lens, a major considerat­ion for us wildlife photograph­ers. A wider aperture also provides the potential for smoother background­s and better rendering of elements such as bokeh.

Most importantl­y, for many photograph­ers, is the ability to use teleconver­ters, which perform amazingly well with prime lenses, increasing their reach by 1.4 to 2x the focal length. Indeed, many modern prime lenses now come with built in teleconver­ters.

A 600mm prime lens becomes 840mm with a 1.4 x teleconver­ter, and 1,200mm with a 2x. The advantages of this extra reach are obvious for bird photograph­y, especially with small passerines, and are a traditiona­l staple of the serious wildlife photograph­er’s kit.

In my experience, although this has improved with the newer zoom lenses and teleconver­ters, teleconver­ters still don’t work well with zoom lenses. The addition of a teleconver­ter increases the minimum aperture of the lens, reducing its light gathering properties making it ‘slower’. Prime lenses and their larger minimum apertures cope much better with this aperture reduction, zooms perform much more poorly in comparison. Optically, a zoom/ teleconver­ter combinatio­n often results in soft-looking images and, consequent­ly, I would avoid pairing converters with zoom lenses.

For me at least, there are three main disadvanta­ges of prime lenses over zooms. Firstly, there is the lack of focal versatilit­y. With a fixed focal length there is no ability to alter the compositio­n of a scene without moving closer or further away from the subject – not something that tends to work well when photograph­ing wildlife.

A zoom lens offers this flexibilit­y with a turn of the lens barrel. Secondly, prime lenses tend to weigh far more than zooms, often necessitat­ing the use of a tripod and gimbal head.

Personally, I hate the restrictio­ns that come with a tripod, preferring to handhold for maximum flexibilit­y. I wouldn’t relish holding a lens more than twice the weight of my zoom all day, although certain camera brands are now producing lighter weight prime options by compromisi­ng on minimum aperture.

Thirdly, and perhaps the most important considerat­ion for most, is price. Taking examples of current Nikon equipment, a prime 600mm f/4 lens weighing 3.26kg

will set you back a cool £14,500, while a 180-600mm f/5.6-6.3 weighing 2.14kg costs a much more palatable £1,800. The lighter weight (1.47kg) 600mm f/6.3 sits in the middle at £4,800. Other manufactur­ers will offer different options and prices, but the difference­s will likely be similar in percentage terms.

I don’t own a prime lens, as I see no use for it in my photograph­y. I much prefer the flexibilit­y that a zoom lens provides, not to mention the cavernous difference in price. I also believe that modern zoom lenses are so optically advanced that they offer no discernibl­e difference in the final image from the performanc­e of a prime equivalent. There are numerous videos on popular social media platforms that will show detailed comparison tests between prime and zoom lenses. Most of these involve the content producer photograph­ing test cards with the same camera paired with the different lens options.

The resulting images are reviewed in microscopi­c detail to illustrate the superior performanc­e of one lens over another. This may make for interestin­g content, however, in reality, these difference­s are minute, and I would challenge anyone to distinguis­h between the images taken in the field and rendered at normal size on social media or in print (which is where the majority of images are published). It must be remembered that we have cameras that are now capturing way more pixels than ever before, amplifying imperfecti­ons in a way not seen previously. You can pixel peep all you like, but you’ll not be showing your image to the world on a high resolution screen at 200% magnificat­ion. It is how the image is used in practice that is the most important considerat­ion.

The huge increase in pixels provided by modern cameras also gives us the opportunit­y to crop our images much more harshly than before, creating the equivalent of a teleconver­ter paired with a camera with a lower pixel count. I would far rather crop more from a sharp image than less from a softer photograph.

To illustrate all of these points, I’ve included two different images above, of a Tufted Duck taken in similar lighting conditions and with the same camera. The difference is that one is taken with a 500mm f/4 prime paired with a 1.4x converter, the other with a 200-500mm f/5.6 zoom lens and cropped more tightly in postproduc­tion. The prime lens shows a slight edge when viewed on my high resolution monitor at 200%, but can you see any difference in quality when the images are printed in this magazine? I doubt it.

The Kestrel image, shown above left, was taken a few weeks ago while on a walk with my dog over Salisbury Plain, using my go-to combinatio­n of Nikon Z9 and 180-600mm f/5.6-6.3 lens. This pairing is light enough for me to carry for miles and to handhold all day long – I wouldn’t be so keen on carrying a 600mm f/4 prime (and try getting a 600mm f/4 prime in your cabin baggage on a flight).

The zoom provides all the focal combinatio­ns I will need in one lens and the image quality is excellent. I happened across this Kestrel hunting over the grassland, returning regularly to this fence post. I couldn’t get too close without disturbing it, but managed to crouch behind some tall grass that acted as a nice frame and hid me from the bird. I have cropped 75% from the original frame to

Both these images of Tufted Ducks were taken in similar lighting conditions and with the same camera. However, one (left) is taken with a 500mm f/4 prime lens and 1.4 teleconver­ter, while the above image was taken with a 200-500mm f/5.6 zoom lens, and cropped heavily.

achieve the compositio­n I wanted, but this still leaves me with a very useable, and saleable, image.

In conclusion, the standard of the zoom lenses on offer in today’s market is of a quality not seen before, and they offer amazing value for money and huge versatilit­y over their prime equivalent­s.

Access to affordable kit of exceptiona­l quality has never been better, and I see no place for a heavy and expensive prime lens in my camera bag. Granted, prime lenses still have their place for some forms of wildlife photograph­y; however, my advice would be to forego the expense and instead explore the zoom options available for your camera system – your wallet (and your back) will thank you.