Improving your home’s thermal efficiency is a great way to reduce your household energy bills. A thermal camera like the Flir C3-X can show very clearly where the heat losses and gains are happening around your home, such as gaps in your ceiling insulation, air leaks around window frames or heat loss through your windows that could be fixed with more effective blinds or curtains. 

But it takes a bit of practice to use a thermal camera effectively and to understand what the images are revealing. Not to mention thermal cameras can be expensive. We take you through the basics of using this type of camera and point out some options for borrowing one rather than buying it outright.

How does it work?

The Flir C3-X has an infrared lens as well as a regular digital camera lens and can take photos in the infrared spectrum. Heat radiation is in the infrared range, and the camera detects this heat and converts it to a digital image, just as a regular digital camera converts visual light. The result is a thermal, or thermographic, image.

Below are two example photos, taken on a hot day in Sydney (when it was well over 30°C outside). The images are colour scaled, with dark colours representing the coolest parts of the room, and bright colours the hotter parts. At the left of the image you can see the range of temperatures detected, and in the top left are two specific temperatures: at top, the dead centre of the photo, and below it, the temperature of the area marked by the circle on the rectangular zone.

There’s a choice of several colour palettes for the heat photos and we used the default (as in the photos above)

Using the Flir C3-X

The C3-X is a simple point-and-shoot digital camera with a large 640×480 pixel rear touchscreen for framing and displaying your photos and navigating and using the options menus. There are on/off and save buttons on the top edge and a USB-C port on the side for charging and connecting to a computer.

If you create a FLIR Ignite online account, you can upload your photos to the Ignite website for easy viewing and sharing online (this requires the camera to be connected to a Wi-Fi network). You can also connect the camera via the supplied USB cable or via Bluetooth to your computer and copy the images across.

You can download comprehensive instructions from the on the Flir website.

It’s recommended to have the camera professionally calibrated once a year, which can be an expensive process.

Tips for taking thermal photos

• Be careful of any highly reflective surfaces in the image area, as they can cause inaccurate readings. It’s best to aim the camera at a dull (matte) surface.
• Avoid focusing on any area that’s in direct sunlight.
• Pay attention to the range of temperatures displayed for the image; the colour mapping can give an impression that there are very cold areas and very hot areas in the photo, but they may actually be only a few degrees different.
• In summer, areas inside your home with air leaks or poor insulation will show as hot spots, as heat is leaking in from the exterior. In winter, these same areas will tend to show as cold spots, as the indoor warmth is leaking out.
• For best results, take the time to read the camera’s instructions – you may need to adjust some of the settings in different circumstances. For example, in its default automatic model the Flir C3-X constantly adjusts the level and span (temperature scale) of the image, which will give a good result in most cases. However, in manual mode you can adjust the temperature scale to be close to the temperature of a target object in the image, which can help detect any anomalies or small temperature differences in that part of the image.
• When using the camera in potentially unsafe areas such as roof spaces or construction zones, be aware of your surroundings and personal safety.

Borrowing a thermal camera

If you just want to perform a one-off assessment of your home, then paying $1000 or more for a professional-level thermal camera like the Flir C3-X is probably a step too far. There are cheaper thermal cameras on the market, including thermal camera attachments for your smartphone, but you’ll still be looking at a few hundred dollars. 

That’s why many local councils and sustainability organisations offer cameras like the Flir C3-X on loan to their local residents or members. Councils often offer this service via the local library. Contact your council or search online to see whether there are any offers near you.

Here are some examples of organisations offering thermal cameras for loan:

• .

Thermal cameras can also be hired from tool hire companies.

If you’re a skilled tinkerer, you could even try !

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On this page:

• How a camera takes a photo
• What does aperture do?
• Using shutter speed
• What is ISO?
• Understanding white balance
• Tips for using these camera settings

But this doesn’t give you much creative control or allow you to capture a good shot in less than ideal lighting conditions. Understanding the manual settings on your camera will give you more artistic flexibility and the ability to shoot in different environments. Plus, it’s a lot of fun.

Rather than explain what every single button, dial and mechanism is doing, this guide covers three key settings in photography: aperture, shutter speed and ISO. When you understand the principles, you can put them into practice and truly unlock what photography has to offer.

How a camera takes a photo

The key point you need to remember is that photography is all about light. Every setting will play a part in determining how much light is entering the camera, even if they do other things as well. When photographers talk about adjusting the exposure, they’re referring to adjustments made to various settings to determine how much light is coming in.

That said, the basic mechanics inside a camera are pretty simple. Up until digital photography came along, film cameras would capture an image by letting light fall onto film which created a negative. This technology remains unchanged in modern cameras except film has been replaced by a digital image sensor.

Inside the camera is a shutter. This protects the sensor from being exposed to light until you’re ready to take a picture. When you press the shutter button on top of the camera, the shutter briefly opens to let light in, then closes within an appropriate time to capture that moment.

The shutter is made up of two key components – the mirror and the shutter curtain. When light enters the camera through the lens, it bounces off the mirror upwards towards a prism which directs it into the viewfinder. This is so you can line up or compose your shot.

When you press the button to take a photo, the mirror flicks upwards, the shutter curtain opens and the sensor is exposed. Here, the sensor records whatever it “sees” until the shutter snaps shut. Then the camera software processes the image and it appears on the screen.

What about mirrorless cameras?

There’s an entire category of cameras that have done away with the mirror to save space and weight. This is also the case with compact models and smartphones. Instead, the shutter curtain is the only thing protecting the sensor from light entering the lens and the image you see through the viewfinder is a digital feed.

What does aperture do?

Aperture is a function of the lens that you can set with camera controls. It’s basically the camera’s pupil and is used to adjust two things: the amount of light that comes in and depth of field.

Aperture is displayed as a number called the f-stop, displayed as ‘f/’ followed by a numerical value. The aperture opens up as you lower the f-stop and vice versa. This typically ranges from a maximum aperture of around f/1.8 to a minimum aperture of f/22 in consumer-grade lenses, including cameras with a fixed lens.

Controlling light and depth of field

As you open up the aperture you let more light into the camera and less as you close it. It’s a useful way to naturally adjust the exposure levels without having to rely on boosting the brightness using software later on. But this also affects depth of field.

Depth of field basically determines how much of the image is in focus. Wider apertures create a shallow depth of field, which means that the subject will be in focus but the background will be blurry or soft. A smaller aperture does the opposite and ultimately flattens the photo at the higher end.

You know those photos of people ‘holding up’ the Leaning Tower of Pisa? That’s achieved using a small aperture. A portrait photographer, however, typically uses a wider aperture to highlight the subject against a softer background.

So, remember: a wider aperture lets in more light but leads to a shallower depth of field. A smaller aperture lets in less light but brings more of the image into focus. If you have a preferred aperture you want to use but don’t have the right amount of light, then you can also control the shutter speed to get the right mix.

Using shutter speed

Most cameras let you adjust the length of time that the shutter curtain stays open. This affects the exposure as well, but it also determines image sharpness especially when shooting moving subjects

Shutter speed is displayed in seconds or fractions of a second depending on the settings. For example, a shutter speed of 1/1000 means the camera is set to take a photo in one one-thousandth of a second. Consumer cameras usually operate within a range of 5–10 seconds down to 1/6400 of a second.

Controlling light and motion blur

As you slow down the shutter speed you let more light into the camera and less as you speed it up. This is because the sensor is exposed for longer (or shorter) periods of time. But this also affects motion blur.

Why does this happen? The camera’s sensor is programmed to record and interpret whatever it sees. So if the shutter stays open for longer, the sensor is going to pick up all the movement that happens in that time frame.

This is why night-time or indoor photos are often blurry when you’re using a camera or your phone in automatic mode. The camera is trying to compensate for the low light by leaving the shutter open for longer, but that in turn captures all the movement and creates a blurry picture.

On the one hand, increasing the shutter speed is a handy way to increase exposure, but you need to keep motion blur in mind. Things like sports, moving vehicles or even photos of your kids running around at a picnic require a faster shutter speed whereas you can lower it if the subjects aren’t moving.

In some cases, motion blur is actually a desirable artistic effect. The most common example of this is waterfall photography. Snap a shot of cascading falls at a higher shutter speed and the water will look kind of jagged and hard. Bump that down and the running water will blur into a nice soft, flowing mist that looks quite calming.

Night-time urban photography is another good example. A low shutter speed will bring out the buildings with street lights and windows punctuating the image, whereas a high one will lead to an overall dark shot. Some cameras also have a Bulb setting where you can leave the shutter open for as long as you like, which is a handy feature for very low light and astronomy photography.

If you want to try slow shutter speed photography then either get a tripod or find somewhere to rest your camera. Humans can’t stand perfectly still, no matter how hard they try, and any tiny movements will add motion blur to the photo.

What is ISO?

ISO is another setting that affects image brightness, but understanding it requires a little bit of history. Back when film was the predominate medium, ISO indicated the film’s sensitivity to light. A higher number meant increased sensitivity which essentially boosted the exposure based on available light sources. A reel of ISO 100 film had low sensitivity to light while an ISO 3200 reel had high sensitivity.

When digital cameras came along they retained the basic principle but converted it to a digital process that you can adjust. Now, most consumer cameras have an ISO range of 100–6400. It’s primarily used to give image brightness a bit of a boost when shooting in darker environments.

So, what’s the catch? Grain, or ‘noise’ to be more specific. As you increase the ISO, the amount of visible grain also goes up. An ISO 100 image will have no noise, whereas an ISO 6400 image will be bright, but very noisy. Modern cameras have built-in noise reduction tools that can compensate for this to a degree, but it affects image clarity at the more extreme end.

Understanding white balance

You know how certain environments can look different depending on the weather, time of day or artificial lighting? Like how a park will look all lush and green on a bright sunny day, but the same spot can appear sort of blue when it’s overcast? This is to do with colour temperature and that’s where your camera’s white balance setting comes into play.

White balance adjusts image colour to make the final picture look natural. These days most cameras handle this automatically, but you can manually tweak white balance as well. This involves picking a pre-set such as daytime, night, or cloudy, or entering a specific value (measured in Kelvins).

You may also want to play with white balance for artistic reasons or to capture a particular mood. The blue hue brought on by a grey, overcast day may not look nice, but you can tell the camera to retain it if you want to capture a realistic scene.

Tips for using these camera settings

Now that you know the basics it’s time to start experimenting. Keep in mind that every adjustment has benefits and compromises so it’s up to you to figure out the optimal combination for the environment, and also the style of photo you’re aiming for.

Say you want to take a photo of your friends at dinner indoors. It’s dim outside but the ceiling lights are pretty bright and you don’t want people to look blurry. Here is where you could try a wider aperture to let more light in with a higher shutter speed to reduce motion blur, and a slightly elevated ISO.

Or maybe it’s daytime and you want to photograph some sport with just a little motion blur to convey movement. This would call for a lower shutter speed, with a higher aperture and the lowest possible ISO to keep the exposure in check.

The best part about living in the digital age is you can learn by taking as many photos as you want without having to worry about buying more film. Theory is good but it only goes so far. It won’t take long to put these concepts into practice and you’ll be shooting exclusively in manual mode before you know it.

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On this page:

• How do we choose which cameras we test?
• How do we score cameras?
• How do we assess camera video quality?
• How do we test camera functions?
• How do we assess ease of use?
• Who are our expert testers?

How do we choose which cameras we test?

Cameras don’t vary in any meaningful way from country to country, which makes an international test possible. However, we only test products that are purchased from retail outlets. Then all cameras are put through the basic tests, but the more sophisticated cameras, such as SLRs go through extra testing.

How do we score cameras?

The overall score is made up of

• Image quality 50%
• Ease of use 30%
• Movie quality 10%
• Monitor/viewfinder 10%
• Flash 0% (we test for flash quality and show you the results but it doesn’t contribute to the overall score as some cameras do not have a flash)

Getting started

Before we begin testing a camera, we make an exhaustive list of its features and specifications. Manufacturers’ specifications often leave out protruding parts or batteries, so we measure most things to try to give you information that relates to actual use.

All computer-related tests are performed on an up-to-date PC with the latest version of its operating system. Five high-quality professional monitors are profiled and calibrated and both the monitors and video cards are adjusted to sRGB colour space. To compare the test results to previous batches, samples from the last batch are re-tested and used as an anchor for scoring.

Subjective tests are evaluated by five people each with their own calibrated monitor to provide the best possible viewing conditions. At no time do they know which camera has produced the image they are judging.

How do we assess picture quality?

Picture quality is evaluated after the photos are transferred to the PC. For all basic tests the cameras are set to full automatic function, including exposure, white balance and focus function, with the maximum resolution and image quality setting in JPEG, unless otherwise stated. Test charts are adjusted to fill the monitor display of the camera. If not stated otherwise, we use a tripod.

Normal pictures/viewing tests

Normal pictures are assessed using the following scenarios:

Portrait in a living room without flash:the light level is at 140 lux and the scene photographed is two metres from the camera. We score overall picture quality, skin tone, colour accuracy, exposure accuracy, sharpness and image noise.

Portrait in a living room with flash: the light level is at 140 lux and the scene photographed is two metres from the camera. We score overall picture quality, skin tone, colour accuracy, exposure accuracy, sharpness and image noise.

Pictures in bright light (with trees, lawn, buildings and sky): lots of contrast, natural colours and a light level of 8000 lux. We score overall picture quality, gradation of colours, colour accuracy, exposure accuracy, sharpness and image noise.

Indoor image of various objects in low light: the light level is set to 30 lux and objects include skin tones, objects with high contrast as well as artificial and saturated colours. We score overall picture quality, skin tones, gradation of colours, colour accuracy, exposure accuracy, sharpness and image noise.

Face detection: an image is taken of two people left and right of the image centre, in front of a bright white screen with some high contrast objects. The image is taken as close as possible to normal viewing angle (47°). The two people are at a distance of one and three metres and the rear screen is at a distance of five metres. We score sharpness and the exposure of the two faces, with preference for the person closest to the camera.

Very low light performance: the light level is set to 11 lux with a similar scene to the pictures in bright light. We score overall picture quality, sharpness, blur, and image noise. In addition, sophisticated cameras are also set to manual and ISO 3200. Exposure, focus and white balance are done manually and images are taken in both JPEG and RAW.

Image stabilisation: we mount the camera on an electro-dynamic shaker and apply recorded human movement in different directions and at different strengths while taking a number of images. This is done with a light level of 11 lux and with the cameras flash turned off. Where possible, the test is repeated with the lens set to a viewing angle of 12°, which puts the target at around four metres from the camera and the light level is adjusted to 1000 lux.

Macro image: we measure the smallest sharp area which the camera can take in macro mode. We also measure the distance between test chart and lens front. The test is performed using automatic focus.

Technical measurements with manual settings

The following tests are measured using manual settings where possible. Sophisticated cameras are appraised using both their JPEG and RAW output.

Resolution: measured at maximum and minimum optical zoom setting at ISO 100 (sophisticated cameras take pictures at ISO 800, ISO 1600 and ISO 3200 and in both JPEG and RAW formats where possible). The test chart is evenly illuminated by two light sources with D65 light characteristic (daylight).

¶Ù¾±²õ³Ù´Ç°ù³Ù¾±´Ç²Ô:Ìýfor both vertical and horizontal planes with the lens set to minimum and maximum focal length.

³Õ¾±²µ²Ô±ð³Ù³Ù¾±²Ô²µ:Ìýmeasured at maximum aperture (smallest F-number) and at an aperture of 5.6 (in both JPEG and RAW format where possible) at ISO 200. The lens is set to minimum and maximum focal length.

Veiling glare: measured at maximum and minimum aperture and at normal focal length with ISO 200 setting and using manual white balance. This measures the amount of stray light in a lens caused by reflections of light between the surface of the lens element and the inside of the barrel of the lens (ISO 9358:1994).

A lens that performs poorly will often show up as producing images with a washed-out look over most of the photo. This is often not as noticeable as other types of glare which may leave a distinctive light spot on an image. Veiling glare can result in a reduction in the contrast of the image as well as the colour saturation.

Reflections: a series of images are taken at maximum aperture (minimum F-number) and minimum and maximum focal length of a dark screen with a bright light source right and left of the maximum horizontal image angle. We do not use a lens hood, even if one is delivered.

How do we assess camera video quality?

Monitors, projectors and video cards are adjusted to sRGB colour space. All measurements and recordings are made using automatic exposure and automatic white balance settings. 

Two one-minute video recordings are made of a scene featuring people with colourful clothes, other objects with fine details and realistic artificial plants at different distances, both at rest and in motion. The automatic focus system and white balance is switched on, if possible. The camera is mounted on a tripod, and about a third of the take is recorded while panning and another third while zooming. Lighting for the tests is under the following lighting conditions at the targets:

• Daylight conditions, 3500 lux (D65)
• Low light, 11 lux.

These recordings are replayed on profiled and calibrated, high-quality monitors or projectors with high resolution (FullHD with 1920 x 1080 pixels and at least 25 (24) frames per second). The test panel evaluates colour fidelity, observing the actual objects (colourful objects and the like) used in making the recordings with appropriate illumination. The recorded images are rated according to the following criteria:

• Sharpness (how faithfully structures are reproduced)
• Colour fidelity (colour neutrality and colour noise)
• Exposure and contrast gradation (also in highlights and in dark areas)
• Overall image quality
• Image and focusing irregularities.

Audio quality

All measurements and recordings are made using the camera’s automatic gain control settings. An audio stereo sample from CD (classical music with high dynamic range and both male and female voices), is played over two high-quality loudspeakers in a room.

First, a reference recording from these samples is produced on a digital recorder with a high-quality stereo microphone at a distance of two metres. The sound pressure level at the location of the microphone is at an average of 65 dB. Two audio recordings are made with each camera tested under the same conditions. Recording is done using the built-in microphone in automatic mode and we create possible noise by using the zoom.

We then listen to the recordings using high-quality headphones and rate the overall audio quality of the sample recordings, at the original volume. Problems with motor, zoom and button noises are noted.

How do we test camera functions?

Flash

We check to see if the flash is ‘intelligent’, that is, the power of the flash automatically adapts to the distance from the subject. We also check flash quality by taking a picture of a test chart in a dark room. The camera is adjusted to fit to the full test chart in the viewfinder/monitor of the camera using the zoom lens. Pictures are taken at one, three and five metres.

The resulting images are appraised for the amount of light put out by the flash, evenness of its illumination and its ability to cope with varying distances. If necessary, we also note reflections/shadows from the camera’s body.

To test flash quality over a long distance we take pictures in a dark room at the camera’s widest angle setting. There are distance marks (small grey cards) at different positions within the room. Their brightness is evaluated for the flatness of the distribution of the flash light across the scene.

Monitor and viewfinder

A panel evaluates the quality of the monitor and viewfinder for readability under different light conditions (sunshine, low light indoor). Adjustments for users wearing glasses (diopter correction) is evaluated as well. In both cases we look for picture quality in terms of colour performance, brightness, contrast, resolution and the speed of the refresh rate (important for precise pictures when zooming or taking photos in panning situations).

Viewfinder: we score usability in bright sunlight conditions and in poor light conditions, the quality of resolution and refresh rate at panning scenes and the size of the image in the viewfinder. For sophisticated cameras, we measure the difference of the size of the image in the viewfinder related to the width stored in the image.

Monitor: we evaluate the monitor’s loss of readability (contrast, brightness and colour) when viewed from +/-30° to left and right and +/-20° to above and below directly in front of the monitor. This test is performed indoors in good light with no light from behind, and in poor light conditions where there is bright diffused light behind the viewer.

We also evaluate the quality of the monitor in playback mode using a test image in JPEG format with fine details and high contrast. Each monitor’s performance is evaluated for resolution, sharpness, contrast and brightness of the display as well as some other errors such as a visible cell structure of the LCD panel.

Focusing

Manual focusing is assessed in low light conditions (11 lux) using objects with high and low contrast. If possible we use assistive technologies such as live view or software magnification.

Autofocus sensitivity involves taking an image in automatic mode and at normal focal length (image angle ≈ 47°) of a test chart at a distance of one metre illuminated by photo lamps. There’s a pattern in the centre of the screen to allow the camera to focus automatically. The power of the photo lamps is reduced, which in turn reduces the contrast of the pattern on the test chart. We measure the luminance of the test chart in cd/m² when the auto focus doesn’t reliably find the focus point any more.

How do we assess ease of use?

Shutter delay

All the camera’s functions are set to automatic and the lens is focused at infinity. The camera is then aimed at a timing display at eight metres and triggered with a sensor attached to the shutter release button of the camera. The test is then repeated at one metre. It’s carried out in both modes for cameras with a choice of phase-detection or contrast-detection autofocus.

Device ready for operation

The device is switched off for at least a minute then switched on and we measure the time it takes before the first still frame is taken. The process is repeated in video mode.

Speed in use

We record the time (in seconds) it takes to carry out five cycles of the following, with the camera set to maximum image quality:

1. Take image.
2. Switch to replay mode.
3. Zoom to certain magnification.
4. Delete image.

There’s a subjective score for how difficult it is to manage the controls while carrying out this test.

Picture taking speed (single shooting mode)

We measure the time it takes to take a picture, from pressing the shutter release until the camera indicates it’s ready to take the next picture. The camera is at its highest quality setting with the flash off.

Picture sequence speed (continuous shooting mode)

Using a consistent illumination (1000 lux) with the camera set at medium focal length, a subject at three metres and with the flash off, we measure the number of pictures/sec or the shortest possible time interval between two pictures and the number of pictures till the buffer is full.

Speed at low luminance level (sophisticated cameras only)

We measure autofocus speed at a luminance of approximately 10 cd/m². All functions are set to automatic and single lens reflex (SLR) cameras use phase detection mode. The test is repeated for single lens reflex cameras in live view mode (contrast detection).

Manuals

The printed documentation and the manuals on CD-ROM or in-camera supplied are evaluated for the completeness of documentation with detailed explanations and examples for using the camera as well as appearance, paper quality, readability of text and sketches

We also consider how easy the structure and content are to understand, and if technical expressions are explained for ‘non experts,’ extra content such as safety hints for electrical danger or damage by static discharge, helpful hints in case of malfunction and tips on how to care for rechargeable batteries.

The quality of explanations for the use of digital cameras in general and the use of the camera itself also factor in. The quality of the description for connecting to a PC and file transfer do too. We also make sure the table of contents is clear and that the correct manual is supplied.

Inserting and removing memory card

The insertion and the removal of the memory cards is evaluated for how easy it is to grip when inserted, accessibility and ease of use of the eject button, clear indication of which way/side the memory card should be inserted and how easy it is to open the cover of the card compartment.

Release button

Is the release button easy to handle? Does it need much force to depress? (If it’s too stiff there’s a danger of moving the camera while releasing.) Is there a clear indication when the shutter releases?

Autofocus

We give a rating for the quality of the feedback of the toggle point when using the focus lock by half-pressing the shutter release.

Manual focusing

How easy is it to use the focus adjustment in manual mode? Are there easily readable scales or other information aids for determining the object distance?

Zooming

We give a rating for the adjustment of the optical zoom control, speed, responsiveness, number of steps and precision.

Battery change and control of the remaining power

We check how easy it is to change the battery and what indications there are when the battery is getting low.

Lens change

We check for precision, mechanical play and friction when changing larger and smaller lenses.

Video recording

We rate how the device fits into the hand and its comfort for taking video, delay after pressing the record button and feedback during video take. We also look at control of the zoom, the record button and other functions such as focusing.

Video playback

We rate access of playback, pause and stop function, possibility of fast forward and rewind and video clip selection (including sorting, searching and filtering).

Who are our expert testers?

All the tests and procedures described in this article are carried out or overseen by professional testers in specialist camera testing laboratories in Europe.

The test method is decided on by representatives of consumer organisations from around the world who have many years’ experience and specialised expertise in camera testing. Many have formal qualifications, some sit on international standards committees that relate to photography (e.g. ISO/TC42 or Standards Australia MS-065), and they all share a deep interest in photography.

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