All about Camera Lenses

Will Goodlet

All about Camera Lenses

This is not meant to be an exhaustive review of the available lenses for nature photography, more of an introduction to what can be a very complicated subject!

So what are lenses actually for and why do we use different ones?

There is a short answer to that and it has to do with creating different aesthetic effects in our photographs. Of course, there is also the even simpler reason that some lenses are just better performers than others, being brighter or sharper or more durable, easier to use or just more appropriate.

In my experience, there is a standard trajectory to lens buying. We often start out wanting to try every lens there is believing that an armoury of lenses will solve most of our needs.

Over time we acquire or try lots of different lenses. As we mature as photographers we start to find that we don’t want to carry around all the different lens combinations and also that we start to gravitate towards a core set of favourites which suit our own personalities and styles.

How often have I seen a lonely set of Tilt-shift or fisheye lenses on the local second-hand shelf. A testament to some bright-eyed photographer who eventually realised that he or she didn’t really use them as much as they believed they would.

The important thing to do when starting out is to try to resist the temptation to buy all the lenses you can. Instead, try to isolate the ones that will really allow your photography to speak and develop.

Easier said than done!

Find lenses on 500px & Flickr

A good way to start is by identifying what lenses produced photographs you admire. Browsing Flickr or 500px is a great way to narrow down the choices. If you see a look you enjoy delivered by a lens then note it down for future reference.

Obviously, the broad subject matter in nature photography means that we may well require a lot of different lenses. If you shoot both macro and wildlife, for example, then you are going to need different lenses!

So part of the decision-making around lenses should always involve narrowing down what you want to shoot.

Decide what your output will be

Lens choice is also going to be affected by your output. So, are you going to post mainly on social media? Will you sell stock? Will you print your images and if so, at what size? This will all be important in deciding what lens and camera system you will use.

The most demanding of your equipment will be large prints. If you never see yourself producing these then you may not need the same lenses.

Quality and Price

Lens manufacturers compete in various market segments and will typically offer a range of lenses that can do the same job. The idea is to have an offering for every pocket.

Sometimes there is a gem buried in the cheaper lens offering and sometimes a dog in the expensive line-up. Your research will need to identify these - but that will come with experience.

The key thing is not to get confused when you see lenses with seemingly identical specifications and vastly different prices. It may be an older and less advanced model or simply an offering to a different market segment.

In most cases, it is cheaper to buy the right lens for the job over the cheaper lens. I say this because normally what happens is that you upgrade later and consequently had to buy two lenses instead of one.

Do your research, if possible try-out the lens using a rental company. Buy wisely and conservatively.

Second-hand value

Lenses are a lot like used cars. In other words, there is a vibrant second-hand market for well looked after examples. Lenses typically devalue far less rapidly than camera bodies and consequently, it is generally better to put more money into lenses and less into your camera. I say this because almost everyone does the opposite - buying an amazing camera and ordinary lens. You are much better off doing things the other way around.

You should also note that some lens brands hold their value better than others. It will be different in each country so you should look at your local second-hand market and do some research on which lenses seem to sell and hold value.

Normally it will be the major brands that sell. This is important because when the time comes to upgrade you will need to be able to sell on your current lenses.

Here are a couple of South African websites to try:

OutdoorPhoto - Ormsdirect - SA Vintage Camera Trader

Lenses Have Different Mounts

Starting at the very basic level, lenses are paired with specific types of cameras. It is not usually possible to fit a lens from one camera system or manufacturer onto a camera made by another manufacturer.

Even within one brand or camera manufacturer, they will often produce lenses for two or three different camera systems or formats. You cannot assume that the lens will fit because it is the same brand.

More than this, there was a sea change in the market when digital cameras were invented and also when autofocus and light-metering came along. Some manufacturers were able to provide these features without changing their lens mounts and some were not.

I don’t wish to overcomplicate things but please do not just assume that a particular lens will fit a camera just because it is the same brand!

Modern Camera Systems and lens Formats

Modern cameras, which are the only kind on sale new, have some quirks. If you haven’t read the post on camera types I suggest you do so first before continuing here.

Camera manufacturers make several different types of camera (let’s call these ‘formats’). One format, for example, is Mirrorless and another is the DSLR. Within DSLR there are further formats: Medium Format DSLR, 35mm DSLR, Crop DSLR and Micro 4/3 DSLR and 4/3 Mirrorless. All of these different formats take different types of lens. So when you buy a camera and lens, you are buying into a system, not just one product.

The current leading formats for nature and wildlife photography are 35mm DSLR and Crop DSLR. These two formats are almost the same, sharing mounts and bodies. They key difference is the size of the sensor.

Having a much smaller sensor allows Crop DSLR cameras to use the same lenses as the larger 35mm DSLR. However, lenses made specifically for Crop DSLR’s will NOT WORK on 35mm DSLR’s. This is because the image made by the lens is too small to cover the whole area of the much larger 35mm DSLR’s sensor.

Conversely, the larger image projected by the 35mm type lens, is more than big enough to cover the much smaller Crop DSLR sensor.

This differentiation in lenses, where larger formats work on smaller formats is fairly common and has existed since the days of film (e.g. the Pentax 67 Lenses work on the Smaller Pentax 645 bodies).

Two leading manufacturers of 35mm and Crop sensor bodies are Nikon and Canon. Both of these brands differentiate their lens lineup by format. Commonly the lenses have designations like ‘EF-M’ (Canon Mirrorless Lens), ’EF-S’ (Canon 1.6 Crop Lens) and ‘EF’ (Canon 35mm Lens). You can find out more about Canon lens nomenclature here

‘Nikon 1’ or ‘CX’ is a Mirrorless format lens, ‘DX’ is for 1.5 Crop DSLR’s while ‘FX’ is for 35mm DSLR’s. You can find out more about Nikon lens nomenclature here.

Third Party manufacturers

It is also possible to buy lenses made by 3rd Party manufacturers which work on various brands of camera body. These days the quality of these lenses is getting extremely good, many are better (and cheaper) than the original manufacturers lenses.

It is important to understand that 3rd Party manufacturers have to reverse engineer their connections and signals because the branded manufacturers do not share this information with them. So always bear in mind that a 3rd Party lens might have trouble if you update the firmware on your camera or buy a new body.

It usually doesn’t take long for the lens manufacturer to release firmware updates etc.. for the lens but just be aware that this can sometimes be an issue.

Some superb lenses are made by SIGMA, TAMRON and SAMYANG/ROKINON/BOWER (same lens company with different branding).

Sigma can change the lens mount on their newer lenses to fit different camera brands. This is a key consideration because you may wish to switch camera brands later while keeping your lenses. For example, the new Sigma 500mm F4 lens is touted to be half the price of the Nikon equivalent and 2/3rds Canon. So we are talking $4,000 cheaper than the equivalent Nikon lens!! It is also said to be of better quality and more durable than the Nikon.

Dissecting the Lens

Focal length

Focal length is a key measurement and is often used to describe a lens. Focal length is not the size of the lens. It is the distance from the lens element to the sensor when a subject is in focus.

Longer focal lengths, for example 500mm in 35mm DSLR photography, indicate that a distant object will be magnified. While shorter focal lengths, like 16mm, will indicate that the foreground will be magnified and distant objects will appear smaller.
Lenses with a focal length of between 35mm and 50mm are called ‘normal lenses’ and present a view similar to the one we see though our eyes.

So, in a 35mm DSLR, a 500mm lens would usually be employed to photograph a distant animal in wildlife photography. It eliminates much of the foreground and magnifies the view of the wildlife.

A 16mm would be used to present a wide view with a greater emphasis on foreground objects and tiny background details and a 50mm might be used for undistorted portraits of people.


Aperture is used to control light entering the lens amongst other things. We can change the diameter of the aperture and choose to let more light into the lens or to restrict it.
Aperture is denoted by an F-number or F-stop and confusingly, the larger the number the smaller the hole the light has to squeeze through. So, a 500mm F4 lens has a focal length of 500mm and a maximum aperture of F4 (the largest hole it can make for light to come through).

A 500mm F4 lens can let a lot of light in and is a good professional choice for bird and wildlife photography. A 500mm F5.6 (one stop up in aperture) on the other hand, will only let in one half of the light.

Depth of Field

Depth of Field is largely an aesthetic quality of a lens and the reason I bring it up here is that it is a function of Focal Length and Aperture together.

Depth of field refers to the area of an image with acceptable focus.

When photographing a large object, like a landscape, one generally tries to increase depth of field so that both the foreground and the background are acceptably in focus. Conversely, when photographing a bird or a person's face the preference is often for a shallow depth of field so that distracting elements or the foreground or background are gently blurred out.

A long focal length with a wide aperture will produce a very shallow depth of field and a short focal length with a narrow aperture will produce a large depth of field.

Types of Lens

Prime Lenses

Prime lenses are some of the simplest lenses to make. They are of fixed focal length and typically have fewer and less complicated internal elements. Primes are optimized to perform at one focal length and therefore, generally, they produce the best quality of image.

Primes are a little inconvenient in that instead of zooming in or out on you subject you have to move yourself and the camera either closer or further away to achieve the same framing. Normally photographers that shoot primes will carry more lenses in their bags as well because one prime is not suitable for every circumstance.

Prime lenses are prized because they are often of exceptional quality and in the right hands can produce fantastic images. They are, however, inconvenient to use.

Some example prime lenses for 35mm DSLR's are:

  • Canon 85mm F1.2 L mark ii usm

  • Sigma 35mm F1.4 Art

  • Samyang 24mm F1.4

  • Nikon 600mm F4

Zoom Lenses

Zoom lenses are very convenient because they can operate at a range of focal lengths. This means that you don't need to move closer or further away from your subject to re-frame it. If you think about it, this is super useful, especially in situations where you can't move, for example, in a game vehicle at a lion sighting.

Zoom lenses usually list two focal lengths in their description, for instance, the Canon 70-300mm F4-F5.6 L IS.

The first focal length is the widest the lens can go and the second is the longest. In the example I gave above there are also two apertures listed. This is a variable aperture zoom lens. Variable aperture zoom lenses have maximum apertures that change depending on the focal length you are using.

The advantage of a variable aperture is that it keeps the lens smaller, lighter and less expensive to make. The disadvantage, is that it becomes difficult to expose correctly in manual mode because the aperture unexpectedly changes depending on your degree of zoom.

There are more expensive zoom lenses out there that have constant aperture. Lenses like the Canon 70-200 F2.8 L IS mark ii.

Macro Lenses

Macro lenses can be zooms or primes and they are designed to reproduce a subject at 1:1 (or better) on the image sensor. Most lenses do not do this, so macros have a huge advantage when photographing very small things.

Macros can be zooms or primes but beware the marketing around lenses, some 'macro' lenses are not in fact macros.

Macro lenses need to be exceptional quality to perform well at their task, for this reason, macros can be an excellent choice for more general photography as well. For example, I use my Canon 100mm F2.8 USM, not just for macro work but also for landscapes and portraits. It is a very sharp lens and relatively cheap to buy, especially second hand.

With second hand macro lenses, be aware of dust in the lens. Normally, especially with telephoto lenses, a certain amount of internal dust doesn't matter too much. This is because these lenses are rarely used at narrow apertures and dust remains invisible in the photograph.

Conversely, macro lenses are often used at extremely narrow apertures, dust will definitely be visible in the shot!

Telephoto Lenses

Tele's are often used as wildlife and portrait lenses. The reason for this is that they are capable of producing a shallow depth of field due to their long focal lengths as well as magnifying the subject in the frame.

In 35mm formats, telephotos are lenses of around 200mm or longer. The longest lens one can typically buy is an 800mm and anything over around 400mm is termed a super-telephoto. There are longer lenses out there but they are rare and expensive and usually one-offs.

Wide-angle Lenses

Wide angles have short focal lengths and much wider fields of view. For example a 24mm wide angle has a field of view of about 84 degrees - if you take a picture with it the arc of the horizon is roughly 1/4 of the compass or 360 degree view.

Compare this to the 3 degree view through a telephoto lens.

Wide angles typically emphasize nearby objects in the foreground, distorting them so that they look much larger against the background. This characteristic is known as decompression (while in telephotos we see compression of the view).

It is a prized feature of many landscape styles and consequently wide angles are often favored by landscape photographers.

Normal Lenses

Normal lenses are around the 35-50mm mark and represent a view that is neither compressed nor decompressed. It mirrors the field of view we have through our eyes. These lenses are great walk around lenses and useful for portraits because they do not distort facial features like a wide angle does when photographed close to the subject.

Many kit lenses and cheap primes utilize a normal focal length and these are often some of the cheapest lenses and also some of the best value and best quality lenses out there. For example the Canon 'nifty fifty' 50mm is a famous little lens made of plastic and very cheap but also excellent value - delivering superb image quality and a wide maximum aperture.

A normal lens is effectively always one where the focal length is approximately equal to the diagonal distance across the image sensor. In a 35mm DSLR this distance is 43mm.

In a 6x7 medium format film camera with a negative of 60mm x 70mm a normal lens would be 92mm

Focal Lengths are different on different size cameras

That was a nice segue into something that it is important to understand. Focal lengths are often expressed in terms of the 35mm DSLR format. One gets the hang of what different focal lengths mean for images based on how those focal lengths look and work on 35mm cameras.

However, if the image sensor is bigger or smaller then those focal lengths behave differently. We've seen above that on 6x7 medium format it takes a 90mm lens to look the same as a 40mm lens on a 35mm DSLR.

Exactly the same thing happens at other focal lengths, on a 35mm camera system a 500mm lens is a super telephoto, quite an extreme lens. On a 6x7 a 500mm image has roughly the same look as a 250mm image shot on 35mm cameras.

Now, you are unlikely to run into many medium format cameras when starting out but you will most certainly run into Crop DSLRs.

Crop DSLRs are smaller format sensors at roughly 24mm x 15mm and because of this images shot on them will not look the same as 35mm DSLRs when using the same focal length.

On a Crop DSLR a 24mm wide angle behaves more like a 35mm normal lens because the Crop DSLR has a much smaller sensor.