Photography News 13

Technique PHOTO SCHOOL

Camera class

Everyone has to start somewhere, even top pros, and in our regular Photo School feature we look at the core skills that every beginner needs. This month we feature common focusing questions and problems, and show how to fix them. Plus, find out how to achieve selective sharpening in Lightroom

Words by Kingsley Singleton

n How do I adjust my camera’s AF points, so I can focus on a certain part of the scene? The number of AF points available when shooting, and whether you can adjust their position, is governed by your camera as well as your chosen AF-area mode. Normally, AF points can be moved via the thumb pad or a wheel on the camera body and you can cycle through all those available. If however your AF area is set to auto, 3D or similar, then the camera will choose the point of focus for you and you may only see the target appear when it locks on. The number of points depends on your camera model – DSLRs have a limited number because they’re linked to physical AF sensors, unlike compacts and many compact system cameras which aren’t and therefore can theoretically autofocus at any point. n Should I use just one AF point or several? It depends on your subject. Non-moving subjects are easy to shoot with just one AF point. Moving subjects, which you’d normally shoot in continuous or servo AF mode, can be erratic, so it’s a good idea to use more than one AF point at a time. By changing the AF-area mode you can alter the number of AF points used, expanding the coverage so you don’t miss the subject, typically through one, nine, 21 points and so

on. Your camera’s auto and 3D modes both use all the AF points available ‘invisibly’ to automatically focus on the subject or track it through the frame. n Sometimes when focusing, my camera searches and won’t lock on. Why is this and what can I do to stop it? This is called ‘hunting’ and it happens when the camera is struggling to achieve focus, usually because the part of scene you’re trying to focus on is too dark or lacking in contrast. To stop it, either turn on the camera’s focus assist beam (a light which illuminates the subject to make focusing easier) or use your chosen AF point to focus on a different part of the scene, then recompose. Or focus manually. n The camera sometimes focuses on the background rather than the subject. How can I stop the camera doing this? If focus is on the wrong part of the scene, the camera has incorrectly assumed what you want sharp – it happens with busy scenes. You need to lend a hand. Make sure the camera is in AF-S or one-shot AF and set the central AF point. Now aim that AF point at what you want sharp, focus and then keep the shutter button partially depressed or use AF-L to hold focus.

NEXTMONTH: Setting up tomake themost of your camera’s AF system. Plus the low-down on Lightroom’s very useful Clarity tool

Software skills Part 13: Adding sharpness ADOBE LIGHTROOM Last month we looked at the basic sharpening sliders within Lightroom – found within the Develop module’s Detail panel – but there are other ways to add sharpness to your shots. Firstly, sharpness can be improved using the Local Adjustment tools: the Adjustment Brush, Graduated Filter and Radial Filter. Unlike the Detail panel’s Amount, Radius, Detail and Masking sliders, which are essentially global tools affecting the entire image, the Local Adjustment tools can be used to add enhancement precisely where it’s needed. So extra sharpness can be added in brushstrokes, or in circular or linear sections.

STEP 1: SET UP THE BRUSH Pick the Adjustment Brush tool (K) from the toolbox just under the Histogram, then move to the bottom of the palette and set the brush’s size. As the point is to sharpen with great precision, it makes sense to set a low size. By contrast, keep the Feather high, so that the adjustment is added without causing a hard transition. Set Flow to 100 if you want to add the sharpness all in one go, or a lower level if you want to Brush it over in a few goes. STEP 2: PAINT IN THE SHARPNESS Using the Navigator, zoom to a 1:1 view, find the place where you want to sharpen. Now, in the Brush panel, double-click Effect to make sure the sliders are zeroed, then move the Sharpness slider to the right. Brush onto the image to add the effect and push the Sharpness slider to a higher or lower value to increase or decrease the effect. You can see the area you’ve brushed by clicking on the Show Selected Mask Overlay box. STEP 3: DO ITWITH GRADIENTS If you need to remove the effect from a part of the image, hold Alt to toggle into Erase mode (alternatively you can click Erase next to Brush) and rub out what you don’t need. The Gradient (M) and Radial (Shift+M) Filter tools also have a Sharpness slider, which is used in the same way. When using the latter you’ll again have a Feather slider to control the transition of the effect and an Invert Mask box which keeps the effect within the Radius; great for sharpening just the centre of the image.

Like the other parameters, the Sharpness slider can be set to a negative as well as a positive value. A setting of -100 for instance blurs the image. This can be useful because out-of- focus parts make others seem sharper by contrast.

Photography News | Issue 13