Digital Camera World » lenses

Extension tubes: how to shoot extreme close-ups without spending a fortune

jmeyer — Sat, 27 Apr 2013 23:01:51 +0000

Discover how to use extension tubes to shoot great close-up and macro photography without all the hefty costs.

If the warmer spring weather has got you itching to shoot macro photography but you don’t fancy forking out for a dedicated macro lens, using extension tubes may be the answer.

These hollow tubes fit between your existing lens and camera to enable it to focus much closer than before. And even if you get a macro lens later, you can still use the tubes. Combine them with macro lenses and you’ll get greater than life-size reproduction of tiny subjects.

Most independent manufacturers of extension tubes supply them as a set of three, each of a different size, but original camera manufacturers tend to sell them individually.

There are two main types of extension tube; those with the electronic connections to work fully automatically, and those without.

The latter are slower, because you have to set the exposure and focus manually, and only offer limited metering on most SLRs. But for less than £20 they offer a cheap route into macro photography.

Fully automatic tubes are much more convenient because they enable features such as metering and autofocus. They start at around £90, though.

How to use extension tubes

Attach the extension tube
The tube fits between the lens and camera, so you need to remove the lens. Attach the tube to the rear of the lens, then fit this combination onto the camera. The more tubes you attach, the closer you’ll focus.

Adjust your settings
Some tubes work automatically, but set the lens to manual focus – the camera will struggle to focus accurately at such close distances. Also, shoot in aperture priority mode for control over the depth of field.

Position the camera
With the camera set up, you can position it close to the subject. While you can handhold the camera in bright conditions, it’s good practice to use a tripod, to avoid shake and to enable you to frame and focus your shot more accurately.

Fine-tune the focus
Accurate focusing is critical with extension tubes. With the camera in position, fine-tune the focus by using the focus ring on the lens. Because the focusing range is reduced with the tube, you may need to move the camera backwards or forwards.

A layman’s luide to close-up lenses: common questions and answers

jmeyer — Sun, 21 Apr 2013 01:00:46 +0000

What are close-up lenses? In our latest Layman’s Guide we answer the common questions about these budget alternatives to macro lenses and show the effects they can produce.

What are close-up lenses?
A relatively cheap alternative to proper macro lenses, close-up lenses mount onto the front of a regular lens. They shorten the effective focus distance and give a magnifying effect.

How do they work?
Close-up lenses are often supplied in kits with, for example, +1, +2 and +4 dioptre lenses. The higher the dioptre value of a lens, the greater the resulting magnifying effect will be. It’s like putting varying strengths of reading glasses in front of your camera’s lens.

Without a close-up lens, the minimum focus distance won’t usually enable you to fill the frame with small objects.

Who makes them?
Popular makes include Cokin, Hoya, Kood, SRB Griturn and Tiffen. Prices range from around £20 for individual lenses and inexpensive kits of lenses, up to about £100 for top-quality kits. Reasonably inexpensive yet high-magnification +10 dioptre lenses are available from Hoya and SRB Griturn.

When should I use them?
They’re useful when you want to take close-up shots of objects, so you can fill most of the frame with something that’s quite small. However, only close-range focusing will be available.

Giving greater magnifying power, either stacked or used individually, close-up lenses offer a macro-like view.

How do I attach them to my DSLR?
The Cokin close-up lens is square and fits into a holder. Most other close-up lenses are circular and screw into the attachment thread of the host lens, like regular screw-in filters. You can stack them for greater magnification, but image quality may suffer.

Lens Distortion: 3 ways to fine tune your lens’ performance

jmeyer — Sun, 03 Mar 2013 02:00:10 +0000

Improve focusing and remove distracting lens distortion from your images with these three tips for getting more precise focus and professional-looking photos.

Improve autofocus
Many cameras allow you to make micro-adjustments to the autofocus of specific lenses, to improve AF accuracy.

You can  also apply corrections to remove vignetting (darkening in the corners of the frame)  and control lens distortion automatically, although these can only be used with in-camera JPEGs and TIFFs, not raw files.

Remove raw distortion
For more control, shoot in raw and correct problems in software, such as Adobe Camera Raw.

This shot has dark corners and seems to bow outwards, which is a typical effect of using wide-angles close up, called barrel distortion.

It’s also not straight.  Each of these problems can be dealt with automatically, or manually.

Apply Lens Correction
These problems can also be fixed using Photoshop’s Lens Correction filter. Again, you can use a database of lenses to apply automatic adjustments, and these are very effective at removing vignetting and reducing distortion.

However, in manual mode, you can also correct skewed images and remove colour fringing.

DSLR Lenses: 7 questions photographers must ask about their next piece of glass

jmeyer — Fri, 15 Feb 2013 11:30:32 +0000

Choosing new DSLR lenses can be a bit of a minefield. To help you with your choice we’ve (asked and) answered 7 of the most important questions you need to know about your next optic.

I’m using the zoom lens that came with my camera, but I’d like to add one or two more. Where do I start?

Lenses can be split into three basic types: wide-angle, standard and telephoto. The zoom lens that came with your camera offers a focal length in the region of 18-55mm, giving a wide view at the 18mm end and a standard-ish view at the other – depending on the camera it’s attached to.

A good tip for choosing which new lens(es) to go for is to avoid duplicating your existing focal length range where possible. Take a look at lenses that offer either a wider or longer focal length, depending on the type of things you mainly take pictures of.

But do upgrade your kit lens as soon as you can afford to. It’s been built down to a price so that it can be bundled with cameras, and doesn’t feature the sharpest or brightest glass around.

You’ve mentioned focal length three times. That’s how long a lens is, isn’t it?

Not exactly, but without getting caught up in the magic of physics, think of it this way: focal length has an effect on how much of a scene you can see through the lens. Wide-angle lenses have short focal lengths (such as 10mm) and a wide-angle of view – hence the name.

Some of the widest lenses available can take in almost a 180° view of the scene, and with a lens this extreme you need to make sure you don’t accidentally include your own shoes in the frame.

As the focal length of the lens increases, this viewing angle decreases, to the point where long telephoto lenses of 400mm and above only take in a very narrow view of a few degrees.

OK, so how does a standard lens fit in?

A standard lens for a full-frame digital SLR is 50mm, and it captures roughly the same view as the human eye. However, the smaller ‘APS-C’-sized sensor inside the majority of DSLRs is around 1.5x or 1.6x smaller than a full-frame one.

Subjects appear bigger in the picture, a bit like if you’d cropped a shot in Photoshop, and to get a similar result with a full-frame DSLR you’d need to use a longer lens.

So, a 50mm lens fitted to a regular SLR actually gives you a ‘full-frame equivalent’ focal length of 75mm (50mm x 1.5).

To get the standard angle of view that a 50mm lens gives you on a full-frame DSLR, you need to use a 35mm lens on most other cameras (35mm x 1.5 = 52.5mm).

Nice maths. So, what’s the point of a standard lens?

Pictures produced by standard lenses have a natural quality that lets a viewer concentrate on the subject of the photo. A 50mm prime – the ‘nifty fifty’ – is a great value all-round lens, ideal for portraits, street photography, still lifes and more.

What do you mean by ‘prime’ lens?

Primes are lenses with a single, fixed focal length – such as 24mm, 80mm and 100mm – and the only way to make the subject bigger or smaller in the frame is by using your feet.

Zoom lenses are more convenient as they cover a range of focal lengths. However, you often pay for that convenience with increased weight and compromised optics – primes generally produce sharper pictures and have faster maximum apertures.

Some of the more extreme focal lengths – such as thumping great 800mm telephoto lenses – are only available in prime lenses, too.

So when should I use a telephoto?

Long telephoto lenses are the mainstay of sports and wildlife photographers, as they can’t get close enough to their subject, yet still need to fill the frame, and telephotos enable them to do just that.

Short ones start with a focal length of around 85mm, with long ones stretching to 800mm and beyond.

These big guns are able to produce an effect called ‘compression’, where objects look closer together in the frame than they actually are.

This effect can be put to great use when composing a scene with ‘stacked’ elements – such as a line of colourful boats in a harbour. Telephotos are also fantastic for picking out details in a wider scene.

Do I need a wide-angle lens if my kit lens starts at 18mm?

On most DSLRs, that 18-55mm kit lenses actually give you the equivalent view of a 27mm-82.55mm lens on a full-frame camera. To get a true ultra-wide view, you’ll have to look at lenses in the region of 10mm.

These lenses show heavy distortion at the edges of the frame, and subjects closer to the lens will seem much larger than distant ones. Compose your shot to embrace (or avoid) these effects.

PAGE 1: Common questions about choosing DSLR lenses
PAGE 2: How to buy a second-hand DSLR lens – free cheat sheet
PAGE 3: Getting the best from your DSLR lenses

Tamron 14-150mm Micro Four Thirds lens (28-300mm equivalent) revealed

jmeyer — Tue, 29 Jan 2013 11:56:19 +0000

Tamron has announced the company’s first Micro Four Thirds high-power zoom lens, the Tamron 14-150mm f/3.5-5.8 Di III VC.

The new Tamron Micro Four Thirds zoom lens offers a focal length equivalent to 28-300mm in 35mm / full-frame format.

The Tamron 14-150mm Micro Four Thirds lens also features one Low Dispersion (LD) glass element, two molded-glass aspherical elements and one hybrid aspherical element, which Tamron says thoroughly compensates for aberrations.

Compact and lightweight at 350g, the Tamron 14-150mm comes equipped with the company’s own Vibration Compensation mechanism, which helps reduce blur caused by camera shake and allowing photographers to shoot handheld or film video.

The new Tamron Micro Four Thirds lens’ metal barrel exterior is available i black and silver, and the optic offers a filter diameter of just 52mm.

The Tamron 14-150mm Micro Four Thirds lens’ price and release date were not available at the time of writing.

Tamron 14-150mm f/3.5-5.8 Specifications

Focal length: 14-150mm
(equivalent to 28-300mm in the 35mm/full-frame format)
Maximum aperture: F/3.5-5.8
Angle of view (diagonal): 75˚-8˚ 02´
Lens construction: 17 elements in 13 groups
Minimum focus distance: 0.5m (19.7 in.)
Maximum magnification ratio: 1:3.8 (at f=150mm: MFD 0.5m)
Filter size: 52mm
Length*1: 80.4mm (3.2 in.)
Entire Length*2: 85.24mm (3.4 in.)
Diameter: 63mm
Weight: 350 g (12.3 oz.)
No. of diaphragm blades: 7 (Circular diaphragm)
Minimum aperture: F/22
Standard accessory: Flower-shaped lens hood
Compatible mount: Micro Four Thirds

Nikon 800mm lens gets official release date and price… are you sitting down?

jmeyer — Tue, 29 Jan 2013 10:31:20 +0000

Nikon has announced a new super-telephoto, fixed-focal length optic. Officially unveiling the Nikon 800mm lens at the CP+ show in Japan, the AF-S NIKKOR 800mm f/5.6E FL ED VR lens’ price tag comes at a hefty £15,599.99 / €19,000.00.

But the Nikon 800mm lens offers a number of professional specifications, using high-end components and advanced technologies to lower weight, improve handling, and enhance image quality, Nikon says.

The new Nikon 800mm lens is also the first NIKKOR optic to use technologies and materials such as electromagnetic diaphragm control and fluorite lens elements, alongside more standard features like Vibration Reduction and Nano Crystal Coat.

The Nikon 800mm lens becomes the longest focal length in the NIKKOR range, and is aimed at professional sports and press photographers. However, government departments, the military and other such organisations could also be tempted by the Nikon 800mm lens.

The new Nikon lens’ optical system contains a total of 20 elements in 13 groups, including two fluorite and two ED elements. Using fluorite for the front two elements makes the Nikon 800mm lens’ front portion lighter, the company says, and shifts its centre of gravity to the rear, ensuring comfortable handling and stable operation.

The fluorite elements also deliver superior optical performance, achieving high transmission rates with minimal chromatic aberration and lower dispersion properties than even super ED glass, according to Nikon.

The new Nikon lens also employs the manufacturer’s antireflective Nano Crystal Coat to help keep flare and ghosting to a minimum.

The Nikon 800mm lens is supplied with a 52mm NC filter, with a slip-in filter holder on the back of the lens.

Prototypes of the new Nikon super-telephoto lens were shown at Photokina and Nikon’s Olympic events in London last year, but press were not allowed to handle the optic.

Some of the Nikon 800mm lens’ specs were made available last year, but the addition of a 1.25x teleconverter supplied with the optic is a new detail – extending the super-telephoto lens’ focal length to a staggering 1000mm.

The AF-S Teleconverter TC800-1.25E ED is the first teleconverter to use an ED glass element to correct chromatic aberration, Nikon says, and was developed exclusively for use with the new Nikon 800mm lens – meaning it won’t be sold separately.

The Nikon 800mm lens also incorporates a Silent Wave Motor, and employs three focus modes: A/M (autofocus with manual override, AF priority mode), M/A (switch from autofocus to manual operation in any AF mode instantly), and M (manual).

The Nikon 800mm f/5.6 official spec sheet:

·         Focal length: 800 mm
·         Max. aperture: f/5.6
·         Min. aperture: f/32
·         Lens construction: 20 elements in 13 groups (plus one protective glass)
·         No. diaphragm blades: 9 (rounded)
·         Closest focusing distance: 5.9 m (19.4 ft) in AF mode; 5.8 m (19.0 ft) in MF mode
·         Filter/attachment size: 52 mm
·         Diameter x length: Approximately 160 x 461 mm (6.3 x 18.1 in.)
·         Weight: Approximately 4,590 g (161.9 oz) or 4,725 g (166.7 oz) with the teleconverter attached

The new Nikon 800mm lens release date is expected t be 4 April 2013.

Buying new lenses: 7 questions to ask yourself and key features explained

jmeyer — Thu, 20 Dec 2012 02:00:55 +0000

In this post we answer the 7 key questions you should ask yourself before buying new lenses. We also include our new photography cheat sheet, which breaks down some of the key features to look for in new lenses.

Lenses may look like simple tubes with glass at each end, but a lens can house up to 20 or so individual lenses in a dozen or more groups.

Other parts include the aperture blades and an autofocus motor. Then there are all the electronics needed for communicating settings with your camera. Clearly, lenses are anything but simple, but fortunately you don’t need a PhD in optical engineering to understand how to use them.

The lens you choose to fit on your SLR will determine how your end results will look. The main consideration is focal length. Focal length is the distance between the optical centre of a lens and the sensor, but it’s easier to think in terms of how this affects subject size when compared with a standard lens (see below).

For a camera with a full-frame sensor, a standard lens is 50mm. Lenses with focal lengths shorter than 50mm are known as wide-angle lenses, while lenses with focal lengths longer than 50mm are referred to as telephoto lenses.

Which type you need to use will depend on the subject you’re shooting, and the distance you’re shooting from, but most focal lengths offer creative potential with all subjects.

7 questions to ask yourself about buying new lenses

01 What focal length should I choose?
Think about the type of photography you do and consider lenses with focal length ranges that will enable you to cover every eventuality. Broaden your lens collection so it covers the complete range for your chosen subject before splashing out on ‘faster’ lenses.

Upgrading your kit lens to a better quality lens with a similar range is also worth considering, however, as this will ensure better results at the most commonly used focal lengths (see page 90 for a full group test of standard lenses).

02 What lens ‘speed’ should I choose? 
A lens with a maximum aperture in the range of f/1.2 to f/4 is often referred to as a ‘fast’ lens. Lenses with these wider maximum apertures let in lots of light, allowing you to set fast shutter speeds. They’re therefore useful for action photography and for shooting in low light.

Fast lenses are usually of a high quality, but they’re often bulky and expensive, so they should really only be bought (or hired) for specific subjects or occasions.

Slower lenses, meanwhile, tend to be much cheaper and lighter, although you may need to boost the ISO setting (potentially reducing the image quality because of an increase in image noise) to get the same fast shutter speeds.

As an example, if a lens with a maximum aperture of f/2.8 enables you to set a shutter speed of 1/125 sec at ISO100 for a given exposure, a lens with a maximum aperture of f/5.6 will only enable you to set the same shutter speed if you increase the ISO to 400.

Wider apertures also create smaller depths of field, which is especially useful in portraiture.

03 What is the optical quality like?
It’s only by testing a lens you’ve hired, by reading reviews and by speaking to photographers already using the lens that you’ll know if a lens’s quality will meet your expectations.

Sharpness is key, not just in the middle of the frame, but also at the edges, but things like vignetting and other optical aberrations are important too.

04 What is the minimum focusing distance?  
How close can you get to your subject before the lens reaches its focusing limit? This is an important consideration when choosing a telephoto lens.

It’s all very well getting a lens that offers a huge magnification, but if you can’t get close enough to make the most of it (shooting portraits, for example), then you’ll have to add extension tubes to get closer.

05 Does the filter ring rotate?  
Cheaper lenses often have a front element that rotates as the lens focuses. This causes problems when you’ve got a filter attached – particularly a polariser, the effect of which changes as it turns. The only solution here is to focus first, then turn the autofocus off by switching to manual focus, before rotating the polariser.

06 How much should I spend, and will it make a difference?
Considering that many kit lenses supplied with DSLR bodies cost little more than £100, what kind of benefits can you expect by spending £1,000 or more on new lenses?

For starters, buying a luxury lens will give you a fast constant aperture throughout the zoom range, whereas entry-level lenses tend to be much slower – f/3.5 at their widest angle and f/5.6 or slower at the telephoto end.

This makes them less useful in low light photography, and all but useless if you want to achieve a shallow depth of field. High-end lenses should also be more resistant to chromatic aberration, lens distortion and flare. But remember, there’s no such thing as the perfect lens.

07 How does it handle? 
How a lens feels shouldn’t be overlooked. How heavy is it, for instance? Is the focusing ring smooth or jerky? What’s the zoom action like? Cheap zoom lenses can be a bit wobbly, with too much sideways movement in the front element of the lens when you zoom in.

How to focus your camera for any subject or scene: free photography cheat sheet

jmeyer — Fri, 16 Nov 2012 02:00:04 +0000

Are you tired of soft photos? Few things are as deflating as coming home from what you thought was a great shoot, only to find your images aren’t sharp under closer scrutiny. After all, knowing how to focus is one of the fundamental skills of being a photographer – yet it’s one of the most common photography problems there is.

Thankfully, our latest photography cheat sheet is here to help. We’ve come up with a new set of flowcharts to take you step by step through how to focus your camera for some of the most challenging shooting situations. Master these camera focus techniques and you’ll be well on your way to improving your output.

Our cheat sheet starts with showing you how to focus for portrait photography, then takes you through how to stay sharp for action photography, how to focus for close-up shots and, finally, how to focus for landscape photography so you capture all of the detail in your scene.

To view the larger version of our cheat sheet, simply click on the infographic below to expand the file. Or you can drag and drop it to your desktop to save for later.

Work these techniques into your routine and you should quickly improve your hit rate and find yourself more adaptable to learning how to focus in even more challenging situations!

Superzoom lenses: how much extra reach will a few more mm give you?

jmeyer — Sat, 13 Oct 2012 03:00:59 +0000

One of the common questions we often hear from readers here at Digital Camera World involves lenses – specifically superzoom lenses. And it always comes down to this: when looking to buy superzoom lenses, it can be tempting to pay a little bit more for a longer focal length. But how much extra reach do you really get by shelling out more money for a superzoom with 20 or more extra millimetres?

Our original scene. See below how far into it each superzoom can reach.

In short, the greater the zoom range, the more you’ll compromise on image quality, so it’s best to stick to a standard zoom lens and complement this with a telephoto zoom.

There’s still a lot to be said for the versatility of a superzoom. A few millimetres in focal length makes a big difference at the wide-angle end.

At the telephoto end of a superzoom, an extra 50mm won’t make such a noticeable difference, but can still be worth having.

The main options are the Sigma 18-250mm OS and Tamron 18-270mm VC, both of which feature 4-stop stabilisation.

This is worth having, as the largest aperture at the longest zoom settings is f/6.3. This means that with ‘effective’ focal lengths of 375mm or 405mm, you’ll often be limited to slow shutter speeds (unless you increase your ISO), making camera shake a problem.

Below we’ve provided three examples of the scene shown at the top of this page. In each one we’ve zoomed into 200mm, 250mm and 270mm, respectively, to show what each superzoom lens actually captures at these focal lengths.

Superzoom lens reach: 200mm

Superzoom lens reach: 250mm

Superzoom lens reach: 270mm

Lens distortion: everything every photographer must know

jmeyer — Fri, 12 Oct 2012 10:30:30 +0000

However good your lens may be, you need to know how to spot (and correct) lens distortion. In this post we will explain everything photographers need to know to get the best results from their lenses. We’ll start by answering some of the most common questions about lens distortion, then look at several examples of lens distortion and, finally, try to cut through some of the technical jargon and put some of these concepts into layman’s terms.

Are you suggesting my pricey lens isn’t perfect?

All lenses have optical defects, and create images that aren’t perfect copies of the subjects they’re pointed at. However hard manufacturers try to create flawless optics, there’s simply no way to manufacture a lens that doesn’t suffer from distortions and aberrations to some degree.

So if I pay more money for my lens, I will get a less distorted picture from it?

Cost isn’t necessarily a quality indicator. The amount of distortion your lens suffers is largely dependent on the type of lens and its construction. Price plays a role, but factors such as the focal length are just as important.

The wider angled the lens, the harder it is for straight lines not to appear curved, for instance. Zooms are more prone to distortion than primes – simply because it’s impossible to correct for aberrations at every focal length.

This is no guarantee that a prime lens is perfect – but it’s true that the greater the zoom range (such as with superzooms) the more noticeable these distortions become.

I’ve never noticed any problems with my lens…

That may well be true for many of us. The thing is that lens design has improved tremendously in recent years, and the unforgiving precision of the latest digital sensors has forced the progress in lens design to accelerate. With a good digital SLR and a reputable lens, these distortions are subtle – but they are there.

We’ve never had it so good, then?

Definitely! But something as basic as darkening at the corner of the image is still a problem with modern pictures, just as it was for the Victorian photography pioneers. It’s just that this vignetting effect is not quite so marked these days. In fact, we tend to accept that pictures will be slightly darker at the edges – so we don’t even notice it (and some make their corners darker in Photoshop to exaggerate the effect). Take a picture of an evenly lit white surface, look at it carefully on your computer, and you’ll soon see if it’s brighter in the middle. This darkening effect can be eliminated using custom settings on certain cameras, or by using standard image-editing software.

How many different types of optical distortion are there?

There are dozens of these defects, from astigmatism right the way through to coma, but there are two or three that are particularly worth paying attention to.

Start me off with the easiest to understand, then…

We’ll kick off with curvilinear distortion. This comes in several different types, but the one you’ll see most commonly is barrel distortion. This is really easy to spot when you use an ultra-wide lens, and causes straight lines at the edge of the frame to bow outwards. The effect is even more obvious on a fisheye lens, where these distortions are left uncorrected by the designers in order to get the widest possible field of view.

What other curvilinear distortions are there?

Pincushion distortion is often seen on long telephoto lenses – and causes lines to bend inwards. The effect is usually subtle, and isn’t normally noticeable unless you’re photographing rectangular subjects straight on. Some zooms can show signs of moustache distortion – where one image can show both pincushion and barrel distortion. It’s most commonly seen with wide-angle zooms, and causes straight lines to appear wavy.

What else should I watch out for?

Chromatic aberration is probably the biggest bugbear of the modern SLR photographer. As we zoom in to our pictures, the tell-tale colour fringing that this causes is far more noticeable than back in the days of film (when it would only be seen in big blow-ups).

Where am I most likely to see chromatic aberration?

It affects lenses of all focal lengths, but will be more pronounced on extreme focal lengths, and with less expensive lenses. It’s also worth looking at lens tests for this phenomenon because it affects some models more than others. You’ll see it at the edges of subjects, and towards the edges of the image. It’s easiest to see where you have a white line crossing a darker area – window frames in your picture are a good place to look.

Can I do anything about it?

Yes, it can be fixed during editing. Your camera may even come with a program that will help you correct the problem. Photoshop CS has some good tools for minimising its effect on your pictures. Elements 8 users are not so fortunate, but separate distortion-correcting utilities are available. PTLens is well-regarded, can be tried for free and costs just $25.

PAGE 1: Common questions about lens distortion
PAGE 2: Types of lens distortion
PAGE 3: Why does chromatic aberration occur?
PAGE 4: Learning the lingo