Photography News 06

Technique PHOTO SCHOOL

Camera class

Everyone has to start somewhere, even top pros, and in our regular Photo School feature we’re taking a close look at core techniques that every beginner needs to know. This month, in Camera Class we look at how ISO affects exposure, while Software skills teaches you to save precious time by copying settings across images

ISO 50, 13SECS

ISO 100, 6SECS

ISO 200, 3SECS

ISO 400, 1.6SECS

ISO 800, 1SEC

Words by Ian Fyfe

Aperture and shutter speed affect exposure, but there’s a third vital spoke to the exposure wheel: ISO sensitivity. Which can be an image-saver… n What is the ISO sensitivity? The ISO sensitivity defines the sensitivity of the sensor to light, in line with a standard scale defined by the International Organization for Standardization. The concept has been carried over from film days, when different films had different sensitivities. n How does ISO sensitivity affect exposure? While aperture and shutter speed physically change the amount of light that reaches the sensor, ISO sensitivity determines how much light is needed for a good exposure. Increasing the ISO means less light is needed: doubling it, for example from 100 to 200, halves the amount of light needed for the same exposure. That means you can close the aperture by one f/stop or halve the shutter speed to achieve the same exposure. n When would I use a high ISO sensitivity? The most common reason for increasing ISO is shooting in low light. If you’re trying to hand-hold in this situation, a low ISO will mean a slow shutter speed that causes blurred images. Increasing the ISO allows a faster shutter speed in low light. However, you may also need to increase ISO sensitivity in good light. If you’re shooting a very Software skills Workflow software saves time. Part 6: Syncing and output ADOBE LIGHTROOM Whether you make just a few or many changes to your images, Lightroom lets you apply them across any number of your pictures. Often on a shoot, you end up with a number of similar shots and then this feature of workflow software comes in very handy. With your corrected image showing in the Develop interface, go to Settings in the top bar and select Copy Settings to bring up the Copy Settings dialogue box. Here you can tick the parameters you Words by Will Cheung

ISO 1600, 0.4SEC

ISO 3200, 1/5SEC

ISO 6400, 1/8SEC

ISO 12,800, 1/15SEC

ISO 25,600, 1/40SEC

fast-moving subject you need a fast shutter speed to stop the action. At low ISOs, you may not be able to achieve this, so increasing ISO sensitivity will help. Similarly, if you want a small aperture for a large depth-of-field, you might need to increase the ISO to compensate. n What are the advantages of using a low ISO sensitivity? Using the lowest ISO possible ensures maximum image quality. The higher the ISO setting, the more digital noise there is in an image, as you can see want to copy and apply to similar images. There is a Check All or Check None option bottom left that can speed things up. Once done, hit Copy. Now you can paste these settings (Settings>Paste Settings) on any image in your catalogue. If you want to apply the settings to a consecutive series of images, go to the Library module and then View in the top bar and select Grid (quick key G). The size of the thumbnails can be varied by using the Thumbnail slider at the bottom right just outside the preview area. Make sure your corrected image is highlighted, then hold down the Shift key and click on others that you want to apply the settings to. In this example, the same settings were applied to the following four consecutive images so I clicked on the last image in the sequence while holding down Shift. At the bottom right of the interface you will see Sync Settings. Click on that and the Synchronize Settings box appears; click on Synchronize and all settings will be applied to your selected images. If you wish to apply the same settings to several images but they are not consecutive in your catalogue, you have several options. If it’s only a few images use the copy and paste technique described

in the images above. This appears as luminance noise, a general overall graininess, and colour noise, speckles of false colour. This impacts on image quality, degrading fine details and compromising colour accuracy. To avoid this, when photographing a static subject in low light, it’s better to set a low ISO sensitivity and put your camera on a tripod than increasing the ISO sensitivity for a faster shutter speed. That said, for moving subjects it’s better to increase ISO sensitivity to ensure a fast enough shutter speed, because digital noise is more easily corrected in software than blurring.

NEXTMONTH: Techniques for controlling digital noise. Plus using NR in Lightroom

LEFT Copy settings by going to Settings>Copy Settings to bring up this dialogue box. You can now pick the corrections you want to paste onto other individual images in your catalogue.

RIGHT If you have a series of similar images you want to paste settings to, use Lightroom’s syncing skills. It’s quick, easy and saves time.

previously, or in the Library module click and drag images so they are in the right place, ie. immediately in front or behind the image whose settings you wish to copy.

Photography News | Issue 6