The lens is the eye of your camera and affects how it sees and, therefore, records the scene in front of you.

The power of a lens is measured by its focal length, designated in millimetres. There is a complicated optical definition for focal length, but you will never need to know what it is.

Suffice it to say that a lens with a focal length of around 50 mm is defined as a standard lens, as it approximates the perspective and magnification of the human eye.

A lens with a focal length of less than 50 mm is defined as a wide-angle lens, and higher than 50 mm is defined as a telephoto lens.

Each type of lens has its own characteristics of distortion, magnification and depth of field, which makes it suitable for certain photographic applications and gives it certain creative properties. 

A lens with a single focal length is called a prime lens; a lens with a variable focal length is a zoom lens.

For simplicity, throughout this book I often refer to the focal length of a prime lens, although you can get exactly the same effect by selecting the appropriate focal length with a zoom lens. A 200 mm setting on a zoom is equivalent to using a 200 mm prime lens.

Things to Consider before buying a new lens

Angle of view

A better way to think of the power of a lens is in terms of the angle of view.

In the horizontal plane, the angle of view indicates the width of the scene that can be fitted into the shot.

In the vertical plane the angle of view is an indication of the magnification.

As the lens focal length doubles, the angle of view is halved and vice versa. The horizontal angle of view of a 50 mm lens is 40° on a 35 mm frame (27° on a DSLR with a 1.5x crop factor).

The angle of view of a 100 mm lens is 20° on a 35 mm frame (18° on a DSLR with a 1.5x crop factor).

This means that if you switch from a 50 mm to a 100 mm lens, you will only be able to take in half of the scene in front of you.

Understanding the angle of view is vital when thinking about how your lenses allow you to see the world. These diagrams show you what is going on inside your lens and camera.

A better way to think of the power of a lens is in terms of the angle of view. In the horizontal plane, the angle of view indicates the width of the scene that can be fitted into the shot.

In the vertical plane the angle of view is an indication of the magnification.

As the lens focal length doubles, the angle of view is halved and vice versa. The horizontal angle of view of a 50 mm lens is 40° on a 35 mm frame (27° on a DSLR with a 1.5x crop factor).

The angle of view of a 100 mm lens is 20° on a 35 mm frame (18° on a DSLR with a 1.5x crop factor). This means that if you switch from a 50 mm to a 100 mm lens, you will only be able to take in half of the scene in front of you.

Maximum aperture

When you look through an SLR or a DSLR, you are seeing the picture with the lens opened to its maximum aperture.

When the picture is taken, the lens stops down to the selected aperture to ensure the correct exposure.

The wider the aperture, the brighter the viewfinder when you are looking through the camera.

This benefits both manual and auto focusing and also makes it more possible to shoot in lower light levels without a tripod.

A wider aperture also gives you more control over depth of field (click here).

The speed of a lens is relative to its size and focal length but, as a rule of thumb, a lens with a maximum aperture of 2.8 or wider is considered fast because it allows more light into the camera (and, presumably, because this will permit the use of a faster shutter speed);

an aperture of f4 is about medium; any aperture smaller than this can be considered slow because it delivers less light intensity into the camera, resulting in a slower shutter speed.

The maximum aperture of a lens is quoted in its title.

So a 17-35 mm, f2.8 lens is a wide-angle zoom with focal lengths that vary from 17 mm to 35 mm and has a maximum aperture of 2.8 throughout the zoom range.

An 18-200 mm, f3.5-5.6 lens has a variable aperture depending on the focal length.

It will be f3.5 at the wider end, reducing to f5.6 at the telephoto end. If you set an aperture of f5.6 or smaller, you can zoom throughout the range without it changing.

In terms of resolution, most lenses perform better around apertures of f8 or f11. At wider apertures they can be slightly softer, especially at the edges.

While smaller apertures will give more depth of field, they can suffer from an overall reduction in sharpness due to the light being diffracted by the small hole of the aperture.

This can be countered by increasing overall sharpening in post-processing.

Standard lens (usually 50 mm but sometimes 40 mm or 60 mm)

A standard lens gives roughly the same magnification as the human eye.

Some people mistakenly claim that it also has the same field of view but, in fact, the human eye has a much wider field of view than a standard lens, closer to that given by a 28 mm lens.

The standard lens is much undervalued: its similarity to the human eye encourages the viewer to concentrate on the subject of the picture, rather than on any optical characteristics given by more extreme lenses, and it tends to have a wide maximum aperture, making it useful in low light.

In fact, the maximum aperture can be as wide as f1.4, two stops faster than most professional zoom lenses and around three stops faster than an average amateur zoom lens.

Standard lenses are also compact and lightweight, making them useful lenses to have in the corner of a camera bag.


Wide-angle lenses have a lower magnification than a standard lens and a much wider field of view.

A lens with a focal length of 35 mm to 24 mm is considered a mild wide-angle lens; anything 20 mm and wider is an extreme wide-angle lens.

Typically, it is the field of view that governs the selection of a wide lens. A 28 mm lens will have almost double the field of view of a standard lens, and a 14 mm lens will have twice the field of view of a 28 mm.

It is worth having both a mild and a super-wide lens in your camera bag, especially if you are shooting with a crop sensor DSLR that, effectively, reduces the field of view of your lenses (see chart below).

Crop sensor 1.5x 


Full frame/35 mm 

Focal length and zoom range
These examples show how focal length changes throughout the zoom range and how angle of view is affected by focal length. Examples are shown for full frame and crop sensors.


Telephoto lenses have a greater magnification than a standard lens and a narrower field of view.

Usually, photographers select them for the magnification effect, which makes subjects appear closer than if you had photographed them with a standard lens. Lenses with a focal length from

  • 70 mm to around 105 mm are considered fairly mild telephoto lenses
  • 110 mm to 200 mm are strong telephoto
  • 200 mm and above are super-telephoto lens.

As the focal length doubles, the magnification doubles and the field of view halves.

So, a 100 mm lens has twice the magnification of a 50 mm lens, and a 200 mm lens has twice the magnification of a 100 mm lens or four times that of a 50 mm lens.

It is useful to have a lens in the mild and strong telephoto categories in your camera bag, as they have a lot of uses, from magnifying details to taking close-up portraits without having to intrude on the subject.

Super- telephoto lenses are a little more specialized and are typically used for sport and wildlife shots but you can also use a 400 mm lens for landscapes.

Speciality lenses


A macro lens is specifically designed for close-up work.

The definition of a macro lens is one that allows you to photograph at a ratio of 1:1 (actual size) or greater – much closer than non-macro lenses of the same focal length.

Choose a 60 mm lens as a good general lens for a camera with a crop sensor or a 100 mm lens for a 35 mm film or a full- frame DSLR.


A fish-eye lens has a very wide angle of view and imparts a characteristic circular distortion to the frame.

This distortion can either be used as a creative effect or moderated with software in post-processing to give a very wide view.

Shift lens A shift lens is designed for architectural photography, since it prevents the distortion that happens when a wide-angle lens is tilted upwards to fit a building into the frame.

A shift lens avoids this by ‘shifting’ the front of the lens upwards instead.

Zoom lenses

Zoom lenses allow you to change the focal length of the lens between two values, either by using a focus ring on the lens or buttons on a compact camera.

Moving towards a telephoto setting makes the magnification larger and is often referred to as ‘zooming in‘.

Moving towards a wider setting makes the image appear smaller and is often referred to as ‘zooming out‘.

A lot of photographers get sniffy about zoom lenses, regarding them as low quality and used only by amateurs.

However, while there are certainly some average quality zoom lenses around, there are a lot of very good ones as well.

This is partly because much of the recent development in optical technology and design has concentrated on zoom lenses.

If you are shooting with a modern zoom lens on a DSLR, then you can assume that it has been optimized for digital photography and should produce sharper results, especially at the edges of the frame.

You should also consider whether you really need the best quality lenses:

if you have an entry-level camera and are only going to view pictures on a computer or make moderate-sized prints, then the range of focal lengths provided by a good zoom is probably the most important consideration for your photography.

There are practical advantages to shooting with a zoom lens.

Since you have a range of focal lengths built into one lens, you have more chance of having the right lens on the camera at the right time, allowing you to achieve the composition and crop you require without having to swap lenses.

Cutting down the number of times that you have to change the lens will drastically reduce the amount of dust and dirt that can get on to the camera sensor.

A zoom where all the focal lengths are in the wide range (such as 17- 35 mm) is known as a wide-angle zoom; those in the telephoto range (such as 80-200 mm) are known as a telephoto zoom, and those that run from wide to telephoto (such as 18-70 mm) are know as mid-range zooms.

Many entry level DSLRs come bundled with a cheap mid-range zoom (typically 18-55 mm) that is often referred to as a kit lens.

It is possible to buy so-called super-zooms that run from super-wide to telephoto with a zoom ratio of at least 6x. (A 20 mm to 200 mm lens, for example, has a zoom ratio of 10x.)

A popular focal length range for a zoom on a digital camera is 18 to 200 mm (equivalent to approximately 24 to 300 mm on a full-frame camera).

With a lens like this on the camera, you might never need to change your lens, although, if you were only to take a lens like this away with you, then you really are putting all of your eggs in one basket in terms of mechanical breakdown or damage.

There are also some downsides to the super-zoom. The maximum aperture will be relatively small and will get smaller as you zoom towards the telephoto end.

There will also be some quality issues inherent in any lens that covers such a wide range, although, depending on the resolution of your camera and the size you intend to reproduce your images, these might never become apparent.

That being said, with the improvements in high ISO performance outweighing the smaller aperture, a super-zoom is worth careful consideration by the travel photographer.

You could buy one merely to serve as a one-piece back-up to existing

Prime lenses

All of the main camera manufacturers and also some of the third-party lens manufacturers produce a range of professional zoom lenses.

These will be much better quality than their amateur counterparts and have a wider maximum aperture, giving a brighter viewfinder and better functionality in lower light levels.

A professional lens is also more likely to have a constant aperture, so that your exposure won’t change as you zoom – vital if you are shooting with manual exposure.

Professional lenses tend to have both a built-in focusing motor, which makes focusing quicker, and internal focusing, which prevents the lens element from rotating when the lens is focused; this is a massive advantage when using polarizing and graduated filters.

The downside to professional zoom lenses is that they tend to be larger, heavier and considerably more expensive than the equivalent amateur lens.

They also tend to cover a smaller focal length range. Inquisitive giant tortoise, Cousine Island, Seychelles

Added extras

Teleconverter A teleconverter fits between a telephoto lens and the camera to magnify the focal length. The most powerful is a 2x teleconverter which will make a 200 mm lens behave like a 400 mm lens.

Unfortunately, if the lens starts off with a maximum aperture of f4, it will, in effect, end up with an aperture of f8, losing two stops of light.

To limit the loss of light to just one stop, use a 1.4x or 1.5x teleconverter, which will make a 200 mm lens behave like a 280 mm or 300 mm lens respectively.

Using a teleconverter will result in a slight loss in quality but this is easily outweighed by their compactness and portability.

Before you buy, check that the teleconverter will fit the lens you want to use it with and that the autofocus will still work.

Some teleconverters are optimized for use with particular lenses.

Vibration reduction Some lenses have a vibration reduction or image stabilization gyroscope built in to avoid camera shake.

This may enable you to use a shutter speed up to three stops slower than normal, which can be very useful in low light levels.

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Suggested kits

When you are travelling with photographic equipment there is always a trade-off: you have to balance an item’s usefulness with its weight, bulk and cost.

This is a key issue when you’re getting gear onto planes and while you’re on the road, as you don’t want to be so loaded down that you don’t enjoy your trip.

The amount that you carry will depend as much on your style of travel as your style of photography.

You can take more if you are picking up a hire car at the airport than if you are backpacking around on local buses. You should also consider how important photography is for you.

If not being able to take pictures wouldn’t spoil your holiday too much, then you won’t have to take as much spare kit: one DSLR and lens, with a compact as back-up, might be sufficient.

But if you travel to photograph, then you want to cover yourself for as many eventualities as you can.

If you take just one camera with one lens, one memory card, one battery and one charger, then there will be nothing you can do if something goes wrong, or if you have an equipment failure.

The key characteristics of a successful travel photography kit are inter- changeability and compatibility. You obviously want to make sure that lenses and accessories can be used on any camera you take.

I always carry two identical camera bodies, but, if you choose to take different bodies, try to make sure that they at least take the same batteries and charger.

It might sound paranoid but, if one camera gets stolen, you don’t want to be left with a camera body and charger that are incompatible.

It is not just cameras that you need to think about; you should anticipate other things going wrong and work out how you would cope.

If my laptop breaks, I have a back-up drive with a card reader, so I can still back up my pictures.

You also have to asses what level of quality you need for your pictures.

Although you can take creative photographs with any camera, you will need a better quality sensor and lenses if you want to blow up your pictures to very large print sizes, publish some of your work or enter a reputable photography competition.

What equipment you choose depends on your budget but also on what you want from your photographic trip.

If you don’t need the attendant weight and hassles of looking after larger and heavier equipment, then leave the better quality kit at home and take something smaller.

Below are some suggestions as to the sort of kits that you could take away with you and how you might think of upgrading them.

Minimal kit

Compact camera with nothing else.


This kit will be cheap and easy to carry around. There is no excuse for not having your camera with you at all times. You will be able to concentrate on taking pictures rather than worrying about technicalities.


Your photographic options will be limited: you won’t be able to shoot very wide-angle pictures or have a particularly strong telephoto. Also, you will struggle to have control over the shutter speed and aperture that your camera selects and will probably have to rely on picture scene and automatic modes. With just one camera at your disposal, you will have no back-up should you have any technical failures.

Consider adding

An underwater camera housing, not only to allow you to shoot underwater but also to protect your camera from dust and rainfall; a back-up device and a few more memory cards, so that you can back up your own pictures and not have to rely on internet cafés on the road, and a table-top tripod for night photography.

Minimal DSLR or mirrorless camera kit

Entry-level DSLR or mirrorless camera with bundled kit lens: usually a fairly cheap mid-range zoom.


Any of the current crop of DSLRs/mirrorless cameras will give good-quality results, if they are used correctly. This kit will be fairly portable and will give you a larger sensor and lens than you would get with a compact, with the inherent increase in quality.

Cameras will probably have a number of picture scene modes but also easily accessible auto and manual exposure modes, giving you complete control over the technical aspects of your photography.

These systems are also modular, allowing you to add compatible lenses, flashes and even spare camera bodies as your experience and budget grows.

Disadvantages You will have no spare kit in case of equipment failure and no way of backing-up your pictures without using internet cafés on

the road. Kit lenses are good value but aren’t always the best quality and

will suffer from a limited zoom range.

Consider adding

A wider-range zoom or even a super-zoom that might typically run from 18 mm to 200 mm.

If possible, buy this instead of a kit lens when you purchase the camera. A number of retailers have special deals for kits that they put together with better lenses.

You should also consider adding a compact camera as a spare and, maybe, a back-up device, so that you don’t have to rely on internet cafés.

Extended DSLR kit

DSLR or mirrorless camera with two or three lenses, plus a compact camera and a back-up drive.


Two or three lenses will give you a good choice of focal lengths from wide to telephoto, and some overlap for security. Having a compact camera means that you can still take pictures if you have equipment failure and at times when you don’t want to carry the DSLR kit.

Disadvantages This kit is starting to get quite expensive and heavy; make sure that you have good insurance for your equipment.

Consider adding A second compatible DSLR or mirrorless body and a back-up lens, perhaps an 18-200 mm super-zoom that will back-up all of your lenses in one hit. You could also add a speciality lens, such as an extreme wide or fish-eye, or a powerful telephoto lens for wildlife photography. Other useful items would include a portable flash, a back- up device and a tripod.

Comprehensive DSLR kit

Two compatible DSLR bodies with overlapping zoom lenses (wide-angle, mid-range and telephoto), 18-200 mm super-zoom lens, back-up device, tripod, portable flash.

This is the sort of kit for a serious amateur or aspiring semi-professional photographer.


A wide range of lenses gives you a lot of creative options in terms of lens choice. Use the good-quality, wider aperture zoom lenses for most of your pictures, backed up by the 18-200 mm super-zoom.

Two compatible camera bodies gives you good security in terms of equipment failure and loss.

You don’t have to spend a fortune on the second camera body, a cheaper body would do the trick. You could use this kit to photograph just about everything and even start to sell your images.

Disadvantages This kit is a large investment and weighs a lot. You would need to be quite committed to your photography to carry this around with you.

Consider adding Photographers always covet a wider or more powerful telephoto lens. A small laptop is a good investment, so that you can work on your pictures as you go.

Professional kit

This sort of kit encompasses most eventualities and includes a vast range of lens types. My standard photographic gear is:

  • Two identical Nikon professional DSLR bodies Spare charger
  • A range of overlapping pro zoom lenses:
  • 14-24 mm f2.8 super-wide-angle zoom
  • 17-35 mm f2.8 wide-angle zoom
  • 28-70 mm f2.8 mid-range zoom 
  • 70-210 mm f2.8 telephoto zoom 

Back-up prime lenses:

  • 20 mm
  • 50 mm f1.8 for low light levels 
  • 180 mm f2.8

Speciality lenses:

  • 300 mm f4 super-telephoto lens
  • 60 mm f2.8 macro lens for close-ups
  • 10.5 mm fish-eye
  • 1.4x and 2x teleconverters

A range of filters and accessories Flashgun, softbox and ringflash adapter Sirui carbon-fibre tripod

Laptop, portable drive, Colorspace back-up device as well as a lot of 16 GB and 32 GB memory cards.


By having at least two lenses in each of the wide, mid and telephoto ranges, as well as two camera bodies, I am covered in case disaster strikes. I also have access to whatever lens I need for every creative and practical situation.


This level of equipment costs a lot; it is also very heavy. Most professional photographers resign themselves to backache and the hassle of trying to get their gear onto planes.

Even if you can afford it, carrying this amount of gear with you will dramatically change your travelling experience.

Consider adding

There is always a new lens or accessory to be bought…

Now Your Turn

Now I would like to know, do you have any question ?

Or maybe do you have some information to add ?

Either way, let me know in the comments below

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