Digital Camera World » How to focus

Banish Bad Pictures: 9 quick fixes for common camera complaints

jmeyer — Mon, 20 May 2013 11:57:45 +0000

Tired of taking bad pictures? Find out how to fix photos in-camera with our simple advice for curing your exposure problems and focusing headaches. We offer solutions for some of the most common photography problems photographers face. So read on to soothe your burning photo composition and colour complaints!

Whether you’re an experienced enthusiast or you’ve just bought your first digital SLR, everybody has problems with their pictures now and then. It’s nothing to be embarrassed about.

In fact, if you’re less than perfectly happy with your shots, it only goes to prove that you’re eager to improve your DSLR shooting skills. And, as the saying goes, you can always learn from your camera mistakes!

However, working out how to solve your dilemmas on your own can prove to be a real headache. Which menu option or control do you need to use to make your pictures look better? Well, you can rest easy, because our team of D-SLR doctors are here to cure all of your camera complaints.

Whether your highlights are looking blown out and over-exposed, or your photos are suffering from camera shake, we’ve got the solutions to your problems.

If you’re finding it impossible to capture photos with a sense of impact, or your images’ colours look out of whack, we’ll help you resolve your issues. Read on to learn the quick and easy way to restore your shots back to health.

Fixing Bad Pictures: Why are all my photos blown out?

Were you shooting in bright daylight?
Photographing landscapes under midday sun can prove problematic. For the best colours and problem-free exposures, try to shoot your scenes with your back to the sun. If that’s not an option, here are two other possible solutions…

YES

Did you try using Exposure Compensation?
Left to its own devices, your digital DSLR can sometimes produce pictures that look lighter or darker than you would like them to. Switch to Av (Aperture Priority) mode and use Exposure Compensation to tweak the overall brightness.

Did you use an ND Grad filter? 
In landscapes, a standard exposure will either result in overly bright skies lacking detail, colour and impact, or striking skies and excessively dark foregrounds.

Using ND Grad filters 
By using a Neutral Density (ND) Gradient filter when photographing landscapes, you make the brightness of the scene more even. You’ll be able to capture the foreground detail as well as the beautiful colour and texture of clouds in the sky.

Try using histograms
When reviewing your shots on your camera’s LCD, get into the habit of checking histograms as well to see if your shots are too bright or dark. You can also check histograms in Levels in Photoshop.

1 Under-exposed 
This shot of a stag is too dark. The majority of the tones are stacked on the left of the histogram.

2 Over-exposed 
This shot is too bright. The majority of the tones are now bunched up on the right of the histogram.

3 Correctly exposed 
This shot is bang on. There’s an even spread of shadows, midtones and highlights on the histogram.

Focus Stacking: how to extend depth of field when shooting close up

jmeyer — Sat, 18 May 2013 00:00:59 +0000

Shooting anything up close requires incredible patience and extreme precision. If your close-up photography isn’t sharp then you’re not only wasting pictures, but you’ve wasted hours of your time. In this in-depth tutorial we’ll show you how to use one of the most amazing Photoshop effects macro and close-up photographers can use: focus stacking.

Below we’ll show you step-by-step how to extend depth of field when shooting close-up by shifting your point of focus in multiple images, which you’ll later stitch together so you can produce images that are sharp throughout the frame.

One of the best things about close-up photography is the wonderful softness that results from working with such a shallow depth of field.

Even at the smallest apertures the plane of focus will stretch to a couple of centimetres at most, and anything outside this range will fall off into beautiful bokeh.

At times, however, this can be a problem –especially if you’d like a completely sharp subject. Stopping down the aperture will increase depth of field, but sometimes this simply isn’t enough to achieve sharpness across the subject from front to back.

The solution: fix the camera to a tripod and shoot several frames, each with a small shift in focus, then use Photoshop to combine the sharp areas to create a single pin-sharp image.

We’ll begin with a series of shots of a flower, captured with tiny incremental shifts in focus. We’ll make global adjustments to all the images at once in Camera Raw, then combine the sharp parts using the Auto-Blend command in Photoshop CS.

Macro subjects usually look best against clean uncluttered backgrounds, but this isn’t always easy to achieve when searching for the best angle.

We’ll neaten up our finished flower by creating a new colour co-ordinated background, then use the Clone tool to remove a few messy areas. Finally, we’ll utilise the High Pass filter for a great sharpening technique that works wonders on edges.

How to create a focus stacking effect: steps 1-2

01 Open in Camera Raw
Copy your start files into a folder on your hard drive, then open Adobe Bridge and go to the folder. Highlight the first image, then hold Shift and click the last one to select them all. Right-click over them and choose Open in Adobe Camera Raw to open the whole batch.

02 Remove the sensor mark
Click Select All at the top left. Now any changes will affect all the images. First let’s deal with the sensor mark on the left. Grab the Spot Removal tool from the Tools palette, set Type to Heal and Opacity to 100%, then drag a small circle over the mark to remove it.

10 reasons why your photos aren’t sharp (and how to fix them)

anicholson — Tue, 14 May 2013 23:01:40 +0000

Getting sharp photos is one of the fundamental goals in photography. If your images aren’t as sharp as you’d like, take a look at our ten-point guide to work out where you’re going wrong and how to get it right next time.

Reason No. 1. Your Photos Aren’t Sharp: Shutter speed too low

In the days of film photography there was a general rule that in order to get sharp images from a hand-held camera the shutter speed needed to be at least one second divided by the focal length of the lens.

So if you were shooting with a 100mm optic the shutter speed needed to be at least 1/100sec, which because of the way shutter speed is set usually translates to a setting of 1/125sec or faster.

This rule still holds today, but it is somewhat complicated by the focal length magnification factors of sub-full-frame sensors and image stabilisation systems.

For example, if a 100mm lens is mounted on a Nikon APS-C format SLR like the D5200, which has a focal length magnification factor of 1.5x, the photographer would need to set a shutter speed of at least 1/150sec.

Canon APS-C format DSLRs like the EOS 650D have a 1.6x focal length magnification factor, so the shutter speed would need to be at least 1/160sec.

The image stabilisation systems built into some lenses and cameras have a mechanism to compensate for accidental camera movement and this allows slow shutter speeds to be used when the camera is handheld.

Many lenses now claim a 4EV compensation, which means that the shutter speed can be reduced by 16x. That’s the difference between 1/125sec and /18sec.

Even with image stabilisation some people are better at handholding a camera steady than others. The amount of coffee and alcohol that you’ve drunk can make a difference as well.

Ultrasonic motor vs ring-type autofocus: how to know which is which

jmeyer — Sat, 23 Mar 2013 14:00:39 +0000

What’s the difference between ultrasonic motor and ring-type autofocus, and how can you tell which is which? The answer is surprisingly simple. Below we tell you everything you need to know.

Motor-based ultrasonic autofocus uses a small motor in the lens that drives the mechanism via gearwheels.

It’s usually not particularly fast but is generally quieter in operation than lenses that have a standard electric motor, or where autofocus is driven by a motor in the camera body.

Ring-type ultrasonic autofocus is based on two large rings that are fitted inside the lens. There’s no motor or any gears as such, and the system is generally faster as well as being practically silent in operation.

In some lenses, such as range-topping 70-200mm f/2.8 telephoto zooms, ring-type autofocus can be so quick that it’s almost instant.

Unfortunately, most companies like Canon, Nikon and Sigma apply USM, AF-S and HSM designations respectively to lenses that have either motor-based or ring-type ultrasonic autofocus.

Don’t know these acronyms? Click here to find out what your lens markings mean

It’s therefore very difficult to know which is which without thoroughly checking through all the specifications before you buy.

If you can try out the lens in a shop before you make your choice, you’ll generally find that if the focus ring doesn’t rotate during autofocus, then it’s a ring-type ultrasonic system, although this isn’t always the case.

Expert Tip
Ring-type ultrasonic ‘rear-focus’ systems don’t have to move the comparatively large front element of the lens. This helps to boost speed.

Autofocus speed will be reduced when using a teleconverter with compatible lenses, and if the widest effective aperture with the teleconverter fitted shrinks below f/5.6 autofocus usually becomes unavailable.

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.

How to calculate hyperfocal distance: free photography cheat sheet

jmeyer — Fri, 08 Feb 2013 01:00:21 +0000

What is hyperfocal distance? Before the introduction of autofocus cameras, the use of ‘hyperfocal distance’ was a popular focus technique used by photographers – and it’s still one of the really neat camera tricks for times when your camera struggles to autofocus in difficult lighting conditions.

Hyperfocal distance is basically the distance that you can focus to at any given aperture, where the resulting depth of field will retain sharpness in the scene from as far away as infinity to the closest possible point.

The depth of field increases greatly when combining smaller apertures with wider-angle zoom settings, so using the hyperfocal distance technique is particularly useful for landscape photography, especially when you’re using a lens that has a built-in distance scale.

Download our free hyperfocal distance calculator table on page 3 of this article

Wide-angle lenses and narrower apertures both produce a greater depth of field. For example, using an 18-55mm zoom lens, you’ll get a much greater depth of field at 18mm with an aperture of f/22 than you will at 55mm using an aperture of f/5.6.

With a wide-angle zoom setting and narrow aperture, the hyperfocal distance will therefore be very much closer. In this case, it would be 77cm as opposed to 28.2m (see table). The ‘crop factor’ of APS-C sensors is a further factor when calculating hyperfocal distance – the figures given here take this into account.

When setting the hyperfocal distance for whatever focal length and aperture combination you’re using, the depth of field will stretch from roughly half the hyperfocal distance to infinity.

Let’s assume you’re shooting at a focal length of 24mm with an aperture of f/11. The hyperfocal distance works out to 2.7m, so everything from foreground objects just 1.35m away, right through to the distant horizon, should look acceptably sharp.

Upmarket lenses usually have a focus distance scale either printed externally on the lens barrel or displayed beneath a viewing window.

This makes life easy, as you can simply switch to manual focus (MF) and rotate the focus ring as necessary. However, many relatively inexpensive lenses don’t feature a distance scale, so setting the hyperfocal distance is more of a challenge.

A neat solution is to use a digital measuring device. Cheap ultrasonic models tend to lack accuracy and give poor performance outdoors, but laser measuring devices, like the Bosch PLR 25 Digital Laser Range Finder, work very well.

This has a range of 5cm to 25m, with an accuracy of within 2mm, and costs about £65. It also includes a laser sighting pointer, for accurately targeting the object you want to use for distance measurement.

Naturally, the hyperfocal distance can vary greatly if you change aperture or zoom setting, so shoot in Av mode to maintain consistent aperture setting and don’t alter the focal length setting after positioning your camera.

Once you’ve set the hyperfocal distance, you can shoot any number of different scenes using the same settings. If you’re moving around a lot, it pays to apply a couple of strips of gaffa tape to lock the zoom ring and focus ring in place.

Even so, review your photos in magnified view on your camera’s LCD, to check sharpness throughout the scene on successive shots.

PAGE 1: What is hyperfocal distance?
PAGE 2: Setting up hyperfocal distances
PAGE 3: Calculate hyperfocal distance with our free cheat sheet
PAGE 4: Tips for sharper landscapes using hyperfocal distance

Master your camera’s autofocus: which AF points to use and when to use them

jmeyer — Thu, 07 Feb 2013 16:42:37 +0000

Using autofocus correctly can solve a great number of the common photography problems you face on a daily basis. But easier said than done, right? Behold the bible on AF points!

In this tutorial we’ll show you everything you need to know to take control of your AF points and nail focus every time you shoot.

Focusing has never been so simple. Use any of the Basic Zone shooting modes – Full Auto, Portrait or Landscape – and your camera does all the work for you. It’s almost too easy.

A light press on the shutter button is all you need and, 99 times out of a 100, the camera will focus in a split-second and you’re ready to fire.

So why is it that many shots simply aren’t sharp in the places that matter, such as the eyes in a portrait or the rolling hills of a landscape? The answer lies in the way that the autofocus system actually works.

Left to its own devices, a typical mid-range DSLR uses all of its nine autofocus sensors, which are spread out in a wide array around the image frame.

There’s one AF point at the centre, one both above and below it, another two to the left and right, and a final pair positioned towards the extreme left and right sides of the frame.

More advanced cameras feature an additional six ‘AF Assist’ points, although these, unlike the first nine, can’t be selected manually.

Near and far
To achieve autofocus in your camera’s shooting modes your camera uses information from all nine  AF points.

It works out the distance of each part of the scene from the camera, chooses the closest object that coincides with an AF point and locks the autofocus at that setting.

This is fine if you want to focus on the nearest object in a scene, but often that’s not the case.  If you’re shooting a sweeping landscape, for example, you don’t want to focus on the grass in the foreground.

In these cases it’s better to select a Manual AF point. And in close-up or telephoto photography, especially with a large, wide aperture that reduces the depth of field, pinpoint accuracy becomes even more critical.

PAGE 1: What your camera’s autofocus points can do for you
PAGE 2: Making the most of your range of AF points
PAGE 3: When to use your different AF points
PAGE 4: How to choose the best AF point
PAGE 5: How to fool your autofocus – and why you should do it

DIY Photography Hacks: make an AF micro adjustment for precise focus

jmeyer — Thu, 24 Jan 2013 01:00:23 +0000

Are your lenses focusing where they should? In our latest DIY Photography Hacks post we show you how to make an AF micro adjustment to get spot-on autofocus with any camera-lens combination

When your viewfinder’s autofocus points turn red and your digital camera beeps, you know your focusing is bang on. Or is it?

Unfortunately, some camera-lens combinations don’t focus as accurately as you’d hope, and a lens that works fine on one camera body may be slightly off on another.

What we’re talking about isn’t so much a focusing issue, but the fact that autofocus may not stop at precisely the correct place.

You may have heard about ‘front-focus’ or ‘back-focus’, and the problem manifests itself with your depth of field not extending in front of and behind your subject correctly, or with ‘soft’ images when shooting wide open.

Need some space
The Datacolor SpyderLensCal will diagnose focusing issues with your camera and lens, so you can then use the AF micro adjustment custom function found on some DSLR models to correct for pin-sharp focus.

You’ll need space; it’s recommended to have 50x the focal length of the lens – that’s 15 metres for a 300mm lens! You also need a brightly lit area to place the photo target, as autofocus will have to accurately lock on.

You’ll also need two tripods: one for the camera and the other to set up the target, aligned to the same height and square-on to the lens. There’s a bubble level on the target to aid precise positioning.

The whole setting can be performed on the camera’s LCD, but it’s best to check the images on a computer.

Short sharp shot
But is it worth doing? We tested six lenses on two camera bodies and none had serious focusing issues. If you suspect focusing problems, however, as images aren’t sharp where you want them, it’s relatively easy to test your system.

On shorter focal-length lenses, especially ones without very wide maximum apertures, it’s hard to identify the exact point of focus on the scale, but it gets much easier with longer focal-length lenses.

Unfortunately, not all camera models allow you to fine-tune autofocus in this way. If your camera has focus problems but doesn’t enable you to perform AF micro adjustment, try an authorised service centre.

The DIY Photography AF calibration solution

How to make your own AF calibrator using a ruler!

It’s perfectly possible to make your own focus calibration aid – all you need is a ruler positioned at a 45º angle placed next to a chart to focus on; use the central mark on the ruler aligned with the target as the point to get in focus.

Another option is to use tethered shooting, aiming the camera at your computer monitor and shooting a specially designed on-screen target and checking the resulting moiré patterns.

PAGE 1: Set up your AF micro adjustment & a DIY solution
PAGE 2: How to test and calibrate your AF

Getting sharp images: every photo technique you need to know (Part 2)

jmeyer — Tue, 22 Jan 2013 12:08:34 +0000

Taking sharp images is the ultimate goal of any photographer, so it’s only natural then that over the past 150-odd years photographers have found a number of different ways to get their pictures pin-sharp.

Last week she covered the basics of getting sharp images, and in Part 2 of her two-part series our head of testing, Angela Nicholson, draws on her wealth of experience and explains all of her best camera tips and other methods photographers have used over the years to get their photos mind-bogglingly sharp.

Sometimes even though your subject is in focus and the camera is on a tripod, images don’t look absolutely sharp when you blow them up to make large prints. There are usually two explanations for this.

The first is that the camera is actually moving very slightly during the exposure, while the second is the pesky matter of diffraction. Fortunately, it’s possible to combat both of these common photography problems and create pin-sharp images using the following techniques.

Best Ways To Get Sharp Images: Steady the tripod

It’s not easy to select the perfect tripod. The steadiest models that keep a camera the stillest are also usually the heaviest, and while this is fine indoors when you’re shooting still life photography or a macro scene, it’s less attractive when you’re planning to stride out across the hills to find the perfect landscape.

As a result we are often forced to compromise a little to find a more convenient balance between weight and sturdiness. However, there are a couple of things that you can do to ensure that a tripod holds your camera still.

The first thing is to try to avoid setting your camera up in the full force of the wind as this can whip round the tripod legs and set them vibrating. If possible, find a little shelter or create some shelter with your body.

It’s also a good idea to hang a weight (your camera bag is ideal) on the shoulders of the tripod to anchor it more firmly onto the ground. Some tripods even have a hook at the base of their centre column precisely for this.

You need to adjust the length of the strap so that the bag pulls down on the tripod, but just rests on the ground and doesn’t not swing about. Any movement of the bag is likely to be translated into camera movement and that’s exactly what you are trying to avoid.

Some photographers also place a small mouldable weight like a beanbag over their camera or lens to held dampen down any vibrations.

This is particularly useful when using long telephoto lenses that emphasise any movement and are more prone to catching the wind than a shorter wide-angle optic.

PAGE 1: Best ways to get sharp images – steady the tripod
PAGE 2: Best ways to get sharp images – get a remote release
PAGE 3: Best ways to get sharp images – mirror lock-up
PAGE 4: Best ways to get sharp images – diffraction

Getting sharp images: every photo technique you need to know starting out

jmeyer — Tue, 15 Jan 2013 11:30:27 +0000

Taking sharp images is perhaps the ultimate goal of any photographer, and it’s only natural then that over the past 150-odd years photographers have found a number of different ways to achieve it.

Our head of testing Angela Nicholson draws on her wealth of experience and explains all of her best camera tips and other methods photographers use to get sharp images.

Apart from a few creative exceptions, one of the ground rules of photography is that the subject should be sharp. Sharp images are something we start to take for granted over time, but in some situations we need to take more control of the camera to make sure it happens.

Fortunately, it’s all pretty straightforward as there are essentially just three elements involved; focus, freezing the subject and keeping the camera still. Let’s take a look at how to do that:

Best Ways To Get Sharp Images: 01 Focus

The first step in creating sharp images is to get the subject in focus. In most situations this is easy, but if you allow the camera to choose the focus point itself there is a chance it will get it wrong, as many cameras tend to assume that the subject is the closest object and near the centre of the frame.

If there’s something between you and your subject then the camera’s AF system may pick the wrong target and the most important part of the image will be soft – especially if you are shooting with a large aperture.

This is an easily rectified situation, just set your camera to allow you to select the active AF point – the mode is usually called something like Single point AF or Select AF, or in some cases the number of available AF points maybe mentioned, for example 51-point AF.

After activating the mode use the camera’s navigation controls to select the AF point that lies over your subject in the frame. If this isn’t possible choose a point that’s near the subject or the central point (as it is the most sensitive) and move the camera so this point is over the subject.

Then half-press the shutter release to focus before recomposing the shot (still with the shutter release button pressed) before pushing the release fully home to take the shot.

This focus-and-recompose technique is incredibly useful, in fact some photographers use it all the time, and you’ll find it gets quicker and easier with a bit of practice.

When using the focus-and-recompose technique it’s important to set the camera to single AF mode rather than continuous otherwise it will continue to focus the lens as the image is recomposed.

PAGE 1: Best ways to get sharp images – Focus
PAGE 2: Best ways to get sharp images – Freeze the subject
PAGE 3: Best ways to get sharp images – Keep the camera still
PAGE 4: Best ways to get sharp images – steady the tripod
PAGE 5: Best ways to get sharp images – get a remote release
PAGE 6: Best ways to get sharp images – mirror lock-up
PAGE 7: Best ways to get sharp images – diffraction