Problem No. 59: If my photos are coming out too light or too dark, how do I fix them?
This is where the exposure compensation function of your DSLR comes in. By pressing the button marked '+/-' and rotating your camera's control dial, you can correct the meter's interpretation of the scene.
Your camera's exposure level scale, measured in stops, is visible in the viewfinder and LCD screen(s), and this is your visual guide to getting it right. The marker in the middle of the scale represents the 'correct' exposure, according to the exposure meter. As you rotate the dial, you'll see an indicator mark move up and down the scale.
When it moves towards the '+' end of the scale, you're making the image brighter; turn the dial in the other direction and the marker moves towards the '-' end of the scale, making the picture darker.
If you're using an optical viewfinder, you won't see this change happening to the image as you do this, but the effects of exposure compensation are simulated in live view and electronic viewfinders (EVFs).
Of course, the amount of compensation you may need to apply depends on various factors, such as the tone of the subject, the lighting and the type of metering being used.
Problem No. 60: The multi-zone metering mode on my DSLR seems to have a habit of giving me over-exposed pictures. Is it better to use one of the alternative options?
The multi-zone metering mode, whether it's Evaluative (Canon), Matrix (Nikon) or similar, should work fairly well in most situations. But if you're consistently getting pictures that are too bright, it's worth dialling in a little negative exposure compensation.
Some cameras enable you to set this as a default value. For high-contrast scenes where you want to set the correct exposure for shadowy areas and let the highlights wash out, or retain highlights and submerge shadows into darkness, it pays to be more selective with metering, using the partial, spot or centre-weighted options.
Spot metering is the most accurate mode, disregarding everything except for a small circle around the centre of the frame or the active focus point (depending on camera model). But it can be the trickiest to use. Green grass is usually good as an outdoor target for taking a reading and locking the exposure setting in.
Canon's partial metering is similar, but uses a larger area. It's particularly useful in backlit situations. Centre-weighted metering uses the whole scene, but the exposure is weighted around 75% towards the centre of the frame.
Problem No. 61: I've heard photographers talk about 'clipping' before - why is this such a bad thing?
The histogram is simply a visual guide to the range of brightness in a scene - from shadows on the left through to highlights on the right. It can be viewed alongside an image once you've taken it, or displayed in realtime during Live View shooting, but it still shows the same thing: an organic shape on a small graph.
If the brightness histogram runs off the left or right of the scale, it means that part of that picture information is being lost, or clipped. There will be no detail captured in the parts of the picture that contain these 'missing' brightness levels, because they exceed the dynamic range of the sensor.
If the histogram is clipped on the left, the darkest shadows are said to be 'crushed', as they will be pure black and hold no detail (to see this illustrated, check out our infographic How to read a histogram).
But the results are nowhere near as ugly as when the histogram is clipped on the right. If this happens, highlights will be 'blown', rendered pure white and detail free. In a digital photo, the transition between bright areas and blown highlights is frequently very harsh, which is why it's more preferable to 'expose for the highlights' in order to retain detail in them (by slightly underexposing the picture) and allow the shadows to block up a little instead.
Problem No. 62: I've read that it's a good idea to take a meter reading with your camera in tricky lighting conditions, but how do I do this?
Digital cameras use a multi-zone metering pattern by default. This analyses the scene and tries to come up with an exposure setting where detail is retained in bright and dark areas alike. In many cases, however, the results can be poor. Switch to centre-weighted, partial or spot metering, which concentrate metering or bases it exclusively on progressively smaller areas of the frame, and you can use your camera as a light meter.
If you're using a zoom lens, zoom in to fill as much of the frame as possible with the area you want to take a meter reading from. For example, green grass works well in a landscape shot, or you can take a meter reading directly from a portrait sitter's face (although consider adding between half a stop and a full stop of positive exposure compensation to lighten pale skin tones).
To capture and lock the exposure setting, press the camera's auto exposure lock button, then adjust the zoom and recompose the frame as required before shooting.
Problem No. 63: When I focus on a particular object in a scene, then tilt the camera to recompose the frame before shooting, I often end up with metering errors. Why does this happen?
This is most common if you're using a relatively dark foreground object to focus on, then repositioning the camera to take in a large expanse of sky. The result is likely to be that the shot is over-exposed and the picture will be too bright.
Canon DSLRs lock the exposure setting completely at the time of focusing, while Nikon cameras bias the exposure when AF is captured, and only allow a fairly limited change in metering. The problem is easily fixed. First position the camera for taking the light reading.
Now press the auto exposure lock button to capture and lock in the exposure value. Next, swivel the camera, apply a light press and hold down the shutter button to lock the focus on your chosen object.
Finally, swivel the camera to compose the frame and fully press home the shutter button to take your shot. You should get accurate metering every time, but review each shot on the LCD screen and if it's too light or dark, dial in some exposure compensation.
Problem No. 64: Why does my camera give different light metering results when I switch between single- and multi-point autofocus modes, even when I'm using multi-zone metering in both cases?
It's only natural to think that your camera's multi-zone metering mode bases the exposure value on the whole scene, so it shouldn't matter how many autofocus points you're using.
In reality, though, many current DSLRs use focus information in addition to the overall brightness in the scene. The reason is that 'intelligent' metering modes think that you'll be focusing on the main point of interest, and aim to ensure that this is exposed correctly. Linking the exposure value to focus points can be a big advantage when you're shooting things like backlit portraits.
In this situation, you're only really interested in exposing the face correctly, regardless of how bright the background is. The catch is that if you're using single-point autofocus in general shooting, and the focus point falls on a particularly light or dark part of the scene, you're likely to get under- or over- exposed results respectively. For this reason it's often better to use multi-point autofocus for landscape photography.
Alternatively, you could switch to the centre-weighted or spot metering options and use the camera's light meter to set the exposure using a part of the scene that's of average brightness. In any case, it's always a good idea to check the histogram on the camera's LCD display and re-shoot using exposure compensation if necessary.
Problem No. 65: In many of my landscape shots, either the ground is too dark or the sky is too bright. Pale skies in particular seem to fade to white and lose all their detail. Is there any way around the problem?
Pale skies are usually much brighter than the land, so if the ground is correctly exposed the sky will wash out. You can use an ND grad filter, but they're quite fiddly. Another workaround is your DSLR's facility for compressing tonal range, such as Nikon's Active D-Lighting or Canon's Auto Lighting Optimizer.
A better solution, though, is to use a tripod and take two shots; one exposed for the sky, the other for the ground. You can then merge them together using an image-editing program such as Photoshop Elements. Even then, branches and leaves that move between shots can cause problems.
The answer is to take a single shot in RAW and ensure the exposure is sufficiently dark. You can then process this RAW file twice to create two images to merge together.
Find out step-by-step how to fix bleached skies in Photoshop.
Problem No. 66: Why do exposures look correct on my camera's LCD and computer screen, but too dark when I print them at home or send them to an online printing service?
We've often wondered if camera manufacturers make their LCDs artificially bright so that reviewed images look really zingy when people try out cameras in photographic shops. Similarly, computer monitors are often set up by default to look good in brightly lit showrooms and shop windows, and are actually too bright for viewing in normal home or office surroundings.
If you're using a good quality photo printer at home (Canon and Epson lead the way), it's better to trust the results of the printed photo and to reduce the brightness of your computer monitor to match. If you want to be high-tech, a ColorVision Spyder 3 Pro is a good gadget for calibrating your monitor, and costs about £100.
Once your computer monitor is set up properly, download some photos from your camera to your computer, but don't delete them from the memory card. Look at the images on the camera's LCD and your computer screen simultaneously, then reduce the camera's LCD brightness until the images look the same.
One thing to bear in mind is that looking at your camera's LCD in bright sunlight may make images look darker than they really are, so it's best to shade the screen in these conditions. For the greatest accuracy when checking exposures, use the camera's histogram function.
Problem No. 67: Why are some of the ISO ratings on my camera unavailable as standard settings, forcing me to switch to an extended range?
One of the greatest advances in recent DSLRs is noise reduction at high ISOs. That said, many cameras split their total sensitivity range into standard and 'extended' ISO sections.
For example, the Canon EOS 600D and Nikon D5100 both have standard ranges of ISO 100-6400, and enhanced limits of ISO 12800 and 25600 respectively. Digital cameras deliver optimum quality in their standard ISO range, with maximum detail and the least amount of digital image noise at their base ISO settings. For DSLRs, this is usually either ISO 100 or ISO 200.
As you increase the ISO rating, more gain is applied, like turning the volume up on a hi-fi, so system noise becomes more apparent. In this case, it takes the form of digital grain rather than the hiss of a hi-fi.
In-camera noise reduction or smoothing reduces the appearance of noise at higher ISO settings, but this usually results in a loss of detail and image sharpness.
To enable reasonably fast shutter speeds in poor lighting conditions, when you can't use a tripod or you need to freeze motion, then you may need to switch to your camera's extended range of extra-high ISO settings.
Even greater gain is applied, which is likely to result in very noticeable image noise that photographers would normally find unacceptable, so these settings are often only enabled by custom functions.
At the other end of the scale, low ISO settings that are one stop below the base sensitivity of the camera are sometimes available. These are handy if you want to use a large aperture to minimise depth of field, or create motion blur with a slow shutter speed.
The trade-off is that you'll typically lose about one stop of dynamic range in the highlights, so they'll wash out to white more readily.
Problem No. 68: My long exposures look grainy. I've seen a Long Exposure Noise Reduction setting on my camera, but it's switched off by default. Why is this?
Despite what you would expect from a noise reduction system, this one serves a different purpose that's specifically for long exposures, and won't reduce the grainy appearance of regular noise. The problem with long exposures of several seconds or more is that so-called hot pixels can randomly generate bright dots throughout the frame.
Recent DSLRs tend to suffer from the effect much less than older designs do, but it can still be a problem. Long Exposure Noise Reduction works by taking a second exposure straight after the main exposure, but with the shutter closed. Often referred to as a dark frame, the whole picture should be black, so any hot pixels are immediately obvious and the camera's processing system can subtract them from the final image.
The drawback is that the time required to take each shot is doubled. For example, if you take a 5 minute exposure, you'll have to wait 10 minutes before you can take another. The camera's battery life, always at a premium for long-exposure shooting, is also halved.
Many photographers therefore prefer to leave Long Exposure Noise Reduction switched off and remove any hot pixels at the editing stage.
Problem No. 69: I've been told it's best to use exposure bracketing for important shots, but I can't find a mode for this on my camera. How does it work?
Exposure bracketing allows you to take a sequence of images while varying the exposure from one shot to the next. For example, if your camera's light meter thinks the correct exposure should be f/8 at 1/125 sec, you could hedge your bets by shooting three images all at f/8, but with shutter speeds of 1/80, 1/125 and 1/200 sec.
This would give you one shot at the recommended exposure, plus one two-thirds of a stop darker and one two-thirds of a stop brighter. You can then be more confident of getting a shot with exactly the right exposure.
For step-by-step instruction on how to use this DSLR feature, see Auto-exposure bracketing: how to conquer high contrast.
Some entry-level DSLRs don't have an exposure bracketing feature, in which case use the exposure compensation control in increments.
Problem No. 70: Because I can alter the aperture/shutter speed combination in Program mode, does that mean that the Aperture Priority and Shutter Priority modes are redundant?
Program shooting mode is great when you need to react to unexpected opportunities without much time to think about exposure settings. The camera takes into account the lighting conditions, as well as the focal length of the lens (or the zoom setting) and sets a sensible combination of aperture and shutter speed to deliver great results, while minimising the risk of camera shake.
This is especially true if you're also using the Auto ISO function. Most modern cameras go further still, with what's often called a 'Program Shift' mode that replaces the conventional Program mode.
For example, if the Program mode automatically sets an exposure of f/8 at 1/250 sec, you can simply turn the camera's main dial to shift the exposure to, say, f/5.6 at 1/500 sec or f/11 at 1/125 sec.
The overall exposure value remains the same, but you're able to enlarge or reduce the aperture, while correspondingly increasing or decreasing the shutter speed. However, Aperture Priority and Shutter Priority shooting modes are still useful.
If you want to maintain a large or small aperture for minimising or maximising depth of field, or simply to keep the aperture at the sweet spot of the lens for maximum image quality, switch to Aperture Priority.
When you want to select a slow or fast shutter speed for creating motion blur or freezing the action, use Shutter Priority
PAGE 1: General Photography Problems
PAGE 2: Using lenses
PAGE 3: Digital camera accessories
PAGE 4: Digital camera settings and controls
PAGE 5: Camera exposure
PAGE 6: Using flash
PAGE 7: Photography technique
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