20 ISO tips to boost your camera skills
November 6, 2017
Whether you want to boost your camera’s light sensitivity or shutter speeds, James Abbott reveals how to get more with his ISO tips.
1. ISO tips: Light sensitivity and noise
ISO is the control that allows you to set the sensitivity of the camera sensor to light. Lower settings make the sensor less sensitive to light, while increasing the ISO makes the sensor more sensitive to light. So as a rough guide, this means that lower settings can be used in bright conditions or when you have a tripod to support the camera.
Higher settings are almost always used to achieve a shutter speed that’s fast enough to allow the photographer to handhold the camera in low light, or to freeze a moving subject with a fast shutter speed. However, the downside is that as you increase ISO, more noise is introduced to the image, which ultimately diminishes image quality.
2. ISO tips: Types of noise
The two main types of noise: chroma or colour, which look like small coloured blotches and flecks and luminance noise, which is the grainy appearance you can see. Both of these increase as the ISO level is raised, and at the highest levels images can become practically unusable. It’s difficult to pinpoint when image quality drops because all cameras handle noise differently, although generally the more expensive professional cameras produce less noise at higher ISO levels.
3. ISO tips: Auto ISO
Auto ISO is a great setting that will change the ISO within a set range to ensure that the shutter speed of the camera is fast enough to avoid camera shake. So you basically set the ideal (low) ISO and the maximum ISO the camera can switch to, and the camera will automatically select the lowest ISO setting it can.
4. ISO tips: Raw vs JPEG
Whether you shoot raw or JPEG files will come down to a number of factors. If you shoot raw you’ll have to remove noise manually during post-production. Whereas JPEGs are processed in-camera, so you don’t have to do any yourself, but you have the option to set the amount of high SO noise reduction, and turn long-exposure NR on or off.
5. ISO tips: Native ISO vs extended
Native and extended ISO refer to actual ISO settings and simulated ISO settings. Let’s say a camera has these ISO settings: L (low), 100-25,600 and H (High). Low would equate to ISO 50 while High would equate to ISO 51,200. If you set High the camera would set ISO 25,600 and then overexpose by 1 stop. As a result, image quality is comparatively lower than a shot taken within the native ISO range.
6. ISO tips: Shooting in low-light conditions with a high ISO
If you’re shooting handheld and don’t have a tripod, you may be forced to shoot at a high ISO. On dull days in dark streets it can be common to shoot at ISO 1600 or more. For a subject like portraiture this isn’t ideal, but it’s preferable to get the shot with noise rather than no shot at all. Sometimes it’s worth cranking up the ISO.
7. How ISO affects shutter speed
As previously mentioned, an increase in ISO makes the camera sensor more sensitive to light. And as well as an increase in noise, another side effect is that the shutter speed becomes faster. The result is that you can freeze movement if the shutter speed is fast enough for the speed of the subject. Another benefit with fast shutter speeds is being able to shoot handheld without a tripod in low light conditions.
Every time the ISO is increased or decreased by a stop (doubled or halved), for example 200 to 400, the shutter speed will increase or decrease each time by 1 stop, such as 1/125sec becoming 1/250sec. If, on the other hand, you intend to shoot a moving subject such as a waterfall and wanted the water to blur, attach the camera to a tripod and shoot at a low ISO such as 100 or 200 in order to keep the shutter speed as slow as possible in the given light conditions.
8. ISO tips: Use ND filters to extend exposure
Keeping the idea shooting moving subjects in mind, if you want to completely blur movement there’s only so far you can go with ISO alone. At ISO 100 the shutter speed for this scene was 0.8sec. It was slow enough to blur the moving water but in other scenarios you may need to extend the exposure time – by using 10-stop ND (Neutral density) filter, it was possible to increase exposure time to 60secs.
9. ISO tips: Auto off for long exposures
When shooting long exposures with or without an ND filter, or simply shooting with the camera on a tripod, it’s best to turn off Auto ISO and set the lowest native setting available. On some cameras this will be ISO 50, 100 or 200. Auto ISO will raise ISO for a faster shutter speed, with the side effect of increasing the noise.
10. ISO tips: Use the AF assist lamp in low light
Some cameras have an AF assist lamp that illuminates when the shutter button is depressed halfway to autofocus. If you’re shooting in low light and using AF, make sure the AF assist lamp is turned on if your camera has one, because it will make focusing much quicker and easier.
11. ISO tips: Keep ISO low for flash
Generally speaking, when shooting with flash it’s often best to shoot with the ISO set low, ideally between 100 and 400 to ensure the best image quality. Flashguns adjust power output when set to TTL mode, so when shooting portraits the subject will most often be perfectly lit. If you’re shooting in trickier situations where you would like the background to expose correctly, you can force the flash to emit a lower light level that’s balanced with ambient light by shooting at a higher ISO such as 800 or 1600.
12. ISO tips: High ISO for shooting starry skies
Astrophotography is hugely popular and requires just a few techniques for success. You’re definitely going to need a tripod and ideally a fast wideangle lens of f/2.8 or more. An f/4 lens would still work, but you’d need to use a higher ISO.
Manually set the lens to focus on infinity, and shoot in manual mode with the shutter speed around 25secs and the aperture on the widest setting. The ISO should initially be set to 3200 and then take test shots to refine the exact setting. You have to use a high ISO to avoid the shutter speed being so long that stars begin to streak.
13. Shoot low-light sport with a high ISO
A combination of low light and high-speed action calls for high ISO. Not only do you need a high enough ISO for faster shutter speeds to ensure you can handhold the camera without images suffering from camera shake, but one fast enough to freeze fast action.
Many sports are played in the evening under floodlights or indoors, which makes an ISO of 3200-12,800 a common requirement to achieve shutter speeds around and in excess of 1/500sec. This high ISO is often combined with a fast telephoto lens with a maximum aperture of f/2.8, and a camera that has excellent high ISO performance.
14. ISO tips: Reducing noise in software
When shooting in raw, and at high ISO settings, you’ll need to remove or reduce noise manually during post processing. The controls available for noise reduction are exactly the same in Adobe Camera Raw (ACR) and Lightroom, with other raw-processing software offering similar controls. In ACR and Lightroom, the Detail panel has two adjustments for noise reduction – Luminance (light and dark) and Color.
Color Noise reduction has the amount set to 25 by default, and even for high ISO images this can be reduced to 15 or 20 to remove coloured specks and flecks. Luminance Noise Reduction is turned off, so you have to apply it only when required. This control is extremely useful for reducing graininess, but if you push it too far image detail begins to look ‘waxy’. Keeping Luminance below 40 is often a safe bet.
15. ISO tips: When to use noise creatively
So far we’ve been concentrating on keeping ISO to a minimum to maintain optimal image quality or to combat exposures in tricky situations, but high ISO can be used creatively to add texture and grittiness to your shots. Documentary photography in particular has a high ISO grainy aesthetic that comes from shooting at high ISO to capture natural light and atmosphere rather than using a flash.
This grainy style works best with black & white images and extends to portraits, street photography and more. Sometimes shooting at a high ISO is a necessity, but when it’s not you can shoot at a lower setting and add grain in post- processing, which means you have the best of both worlds.
16. ISO tips: Mimic noise in Photoshop’s Adobe Camera Raw Filter
Adding noise to your images is easier than ever in Photoshop, Adobe Camera Raw and Lightroom thanks to the Grain controls available in the Effects tab. In Photoshop you can use the Camera Raw Filter to open up the full set of ACR controls including Grain. If you do this, copy the Background Layer and Convert for Smart Filters, which means that you can save the image as a TIFF and then access the ACR filter later if you need to make any further adjustments. To add grain there are three sliders: Amount, Size and Roughness, and they’re all pretty much self-explanatory and quite effective.
17. ISO tips: Recovering underexposure in raw
There may be times when you don’t have a tripod and would prefer to keep ISO lower than, say, 1600. In these situations you’re going to end up with an underexposed image where exposure and detail will need to be recovered during post production.
If you take this route make sure you don’t push the exposure too far because it will introduce noise, and what you’re doing here is essentially the same as using expanded ISO. This is counterproductive unless underexposing to save highlight detail at the expense of darker tones, so it’s better to raise ISO within the native range than to underexpose and then recover.
18. ISO tips: Image stabilisation
When shooting in low light there are several options available to help keep ISO as low as possible. Sure, it will be higher than normal, but lower than it would otherwise be. The first is image stabilisation, sometimes called vibration reduction (VR), which is a technology found in some lenses or in the camera sensor. It basically counteracts small camera movements, and can allow you to shoot at slower shutter speeds than usual, which also means a lower ISO.
19. ISO tips: Shooting wide open (f/1.8, for example)
Fast prime lenses such as a 50mm f/1.8 are an excellent choice for low-light shooting because you can shoot with the aperture wide open to let more light in, which helps to keep ISO lower. Generally, these fast primes don’t have image stabilisation – this is more common with zoom lenses – although Tamron produces a number of fast primes that have this feature, resulting in the best of both worlds.
20. ISO tips: Using a tripod
When it comes to shooting at the lowest ISO possible in low light, there’s no beating a tripod. The advantage is that you can go as low as you like, but this comes at the expense of long exposure where you obviously can’t handhold the camera, and moving subjects will be captured as a blur. The thing is, this is often the point because you might be shooting a landscape or cityscape where you want to capture movement, such as the sea or a crowd of people.