Digital Camera World » sensor

New Canon low-light sensor can record images in pitch dark

jmeyer — Thu, 07 Mar 2013 11:49:01 +0000

A new Canon full frame sensor is capable of recording faint stars and capturing images in extreme low light.

Canon has announced it has developed a new high-sensitivity 35mm full-frame CMOS sensor designed for video recording, which can capture Full HD video with low noise in the darkest of environments, according to the company.

The newly developed CMOS sensor features pixels measuring 19 microns square in size – which is more than 7.5 times the surface area of the pixels on the sensor in Canon’s flagship full-frame DSLR the Canon EOS-1DX.

“Thanks to these technologies, the sensor facilitates the shooting of clearly visible video images even in dimly lit environments with as little as 0.03 lux of illumination, or approximately the brightness of a crescent moon—a level of brightness in which it is difficult for the naked eye to perceive objects,” according to the Canon announcement.

“When recording video of astral bodies, while an electron-multiplying CCD,*2 which realizes approximately the same level of perception as the naked eye, can capture magnitude-6 stars, Canon’s newly developed CMOS sensor is capable of recording faint stars with a magnitude of 8.5 and above.”

Using a prototype camera which housed the new Canon full frame sensor, the company recorded footage of a dark room being illuminated only by burning incense sticks (approximately 0.05–0.01 lux) and video footage of the Geminid meteor shower.

The image below shows a moonlight scene recorded before and after increasing sensitivity using the new Canon full frame sensor.

The company says it his aiming the new Canon full frame sensor at astronomical and natural observation, as well as medical support and the surveillance and security industries.

However, the announcement suggests that through further innovation the sensor could “expand the world of new imaging expression.”

Camera Sensors At Work: how your digital camera turns light into an image

jmeyer — Fri, 31 Aug 2012 01:00:04 +0000

Your digital camera does a lot more work to turn what you see in the viewfinder into a finished image than you probably give it credit for.

Understanding a little of what goes on deep inside your digital camera’s circuitry will help you understand some of the many options that you have to play with.

Our latest photography cheat sheet illustrates the sophisticated process your camera goes through to transform captured light into an image on your screen.

Perhaps the most important thing to appreciate is that your image is only converted into digital form well after it has left the sensor.

The sensor itself is an analogue component, creating an old-fashioned electrical signal that can be tweaked by electronic circuitry to increase the ISO, for instance, amplifying the signal in much the same way as you crank up the volume on your radio.

PAGE 1: How your camera turns light into a digital file
PAGE 2: How sensors work
PAGE 3: JPEGs and Raw files

Infographic: full-frame vs crop factor lenses

jmeyer — Thu, 29 Mar 2012 11:06:43 +0000

SLR manufacturers use different mounts, so you must check the lens you’re buying. But checking the mount doesn’t guarantee compatibility. You also need to ensure it offers the right degree of coverage.

All lenses create a circular image, and the sensor simply records a rectangular portion of this. Some lenses project a large image circle – big enough to cover a full-frame sensor. But when used with a camera with a small sensor, these create a tighter crop – called crop factor.

To create smaller and wider lenses for small-sensor cameras, some lenses create a smaller image circle to begin with, and are thus not compatible with full-frame DSLRs. If they were used on full-frame cameras, the corners of the pictures would be dark.

The infographic below helps illustrate this effect. Simply drag and drop this graphic on to your desktop and you’ll never be confused about crop factor ever again!

Canon sensor cleaning: remove dust in 4 steps

jmeyer — Tue, 27 Mar 2012 15:16:10 +0000

Your Canon DSLR is a picture-taking tool that’s been designed to capture tens of thousands of photos without any problems – and your lenses should provide a lifetime of service, too. But, like all tools, it needs to be looked after properly if it’s to keep running smoothly. By far your biggest concern will be dust, and the tutorial below will show you a simple Canon sensor cleaning technique to keep your EOS camera running smoothly.

We all know that when you change lenses, dust can enter the camera and be deposited on the filter in front of the sensor. Dust can even be generated inside the camera by the friction between moving parts.

Whatever the cause, the result is the same: blotches in the same place on every frame. When you consider that the imaging sensor inside your Canon DSLR is packed with millions of receptors, yet isn’t much bigger than a postage stamp, you can imagine how much detail a minute piece of dust can potentially obscure in an image.

Sensor dust is most noticeable in areas of smooth, pale tones such as skies, particularly if you’re shooting with narrow apertures, and it becomes particularly obvious if you use a narrow aperture and slow shutter speed during a panning shot.

Bear in mind that it’s only once you’ve taken a picture and you’re looking at it on the rear LCD or on a computer that you’ll spot sensor dust. If you notice other specks when you’re looking through the viewfinder, it’s either the viewfinder window or the mirror inside the camera that require a quick blast from a rubber bulb blower.

The Integrated Cleaning System inside your Canon DSLR does a fine job of vibrating most of the offending particles away from the sensor, but it isn’t perfect. Image-editing programs such as Photoshop make removing any shake-resistant spots relatively simple, but it’s better to remove the dust from the sensor directly.

If you’ve got the right tools and lots of patience you can have a go yourself; although bear in mind that you’ll void your warranty, and replacing a scratched sensor doesn’t come cheap! If in any doubt, leave it to a Canon-approved service centre.

What you’ll need to clean the sensor in your EOS camera

A whole industry has built up around camera care products, with sensor cleaning devices in particular taking many different formats. But which items do you really need?

We’d recommend that a minimum on-the- road cleaning kit comprises a bulb blower, brush and microfibre cloth. You can add a set of wet/dry sensor swabs and a sensor loupe if you’re confident of removing dust manually, although with the EOS Integrated Cleaning System doing a genuinely fine job of removing dust particles automatically, this should be a relatively rare requirement.

It’s also a good idea to keep a pack of lint-free Pec-Pads or lens tissues in your camera bag to help remove marks from lens mounts, buttons and LCD screens.

Warning: dust-spotting your Canon camera’s sensor requires a gentle touch and the right equipment.

How to clean the sensor in your EOS camera

Step 1: Try auto cleaning
Make sure the camera battery is fully charged, then select the ‘Sensor cleaning’ option in the second Setup (yellow) menu. Choose the automatic option to start with.

Step 2: Switch to manual
If dust persists, return to the sensor cleaning menu and select the manual option. This locks the mirror up and opens the shutter. Remove the lens to get access to the sensor.

Step 3: Use a blower
First, use a manual air blower to dislodge any particles – face the camera down so that these fall out of the body. Avoid using a compressed air can. Now take a test shot.

Step 4: Start dry cleaning
If dust remains, charge a sensor brush for ten seconds and carefully drag this over the sensor. If dirt is stuck to the sensor, do a wet clean with a swab and sensor cleaning fluid.

After you’ve finished your Canon sensor cleaning…

When the sensor has been cleaned – either automatically by the camera or manually, by you – take a test shot to check that all is clear. Switch the camera to Av mode, and set the smallest aperture available on the lens.

Photograph a bright, clean area – a piece of white paper is ideal – with the lens manually focused at a close distance. Upload this shot to your imaging software and apply Auto Levels or the equivalent to show up any specks.

The bottom of the image actually represents the top of the sensor, so flip the image vertically prior to cleaning your sensor to find out where on the sensor the dust lies. A sensor loupe – a device incorporating a magnifying lens and lights that fits over the lens mount – is also a great aid here.

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Full frame DSLR: do you really need one?

jmeyer — Tue, 07 Feb 2012 06:00:45 +0000

Owning a full-frame DSLR, such as the Canon EOS 5D Mark II or the Nikon D700, is the ambition of many photographers. ‘After all,’ they think, ‘bigger must be better’ – and these cameras, with their supersize sensors, are what all the top professionals seem to use.

Switch to a full-frame DSLR and your pictures will automatically be better – or so the hype goes. But this is only partly true… A full-frame sensor camera just takes different – not necessarily better – shots than Nikon or Canon DSLRs with the more standard APS-C-sized sensor.

So, what exactly do we mean by ‘full-frame’? A full-frame DSLR from Nikon or Canon or Sony has a sensor that’s the same size as a frame of traditional 35mm film, measuring 36x24mm. The more popular APS-C sensor cameras have much smaller 22x15mm sensors. This means, a full-frame sensor has over 2.5 times the surface area of an APS-C sensor.

Sure, size has certain advantages, but there are distinct drawbacks, too, to making the switch up to a full-frame DSLR.

Camera selection
To upgrade to a full-frame DSLR, prepare to pay a premium. For instance, the street price for a Canon 5D Mark II body is around £1,700, while Canon’s flagship EOS-1Ds Mk III body is £5,250! The added production cost of the bigger sensors means that full frame DSLRs aren’t launched all that often. Today’s Nikon D800 announcement, nearly four years after the release of its predecessor, the Nikon D700, is a shining example of this.

Because full frame DSLRs are less frequent, though, this means you don’t get as much choice as with APS-C.

Image quality The biggest advantage of full-frame is image quality and image size. Both the Canon EOS 5D Mark II and 1Ds Mark III full-frame DSLRs, for instance, come equipped with 21.1-megapixel sensors, and crucially these sensors are over two-and-a-half times bigger – and have much larger individual pixels (or photosites) – when compared to APS-C cameras.

It is not the number of pixels that really counts – APS-C models such as Canon’s EOS 7D and EOS 550D have almost as many photosites, thanks to their 18-million pixel count – but the size of the photosites is crucial to image quality.

Bigger individual light sensors capture more light – and this means that less electronic noise is created. You notice this most as you increase the ISO setting – with this noise creating a coloured mosaic pattern that is particularly noticeable in shadow areas.

Crop-factor effect
The size of the sensor also changes the amount of the scene captured by the camera. Although APS-C and full-frame cameras can share many of the same lenses, the visual effect they provide is different. It is the angle of view that actually changes – as the smaller sensor covers less of the image projected by the lens.

This is known as the crop factor – which compares the angle of view with that seen by a traditional full-frame 35mm film SLR. With full-frame DSLRs the crop factor is 1x – so effectively can be forgotten. A 24mm lens gives the same angle of view as a 24mm lens before the age of digital cameras.

Top: Full frame DSLR at 24mm. Bottom: APS-C sensor DSLR at 24mm.

An APS-C sensor sees a smaller angle of view – with a crop factor of 1.6x. This means the same 24mm lens actually captures the angle of view of a traditional 38mm focal length setting (24×1.6=38). So if you want to capture sweeping wide-angle vistas, a full-frame camera allows you to take in more of the scene in front of you than an APS-C model with the same lens.

The flip side is that the crop factor effect of APS-C cameras becomes an advantage when shooting distant subjects.

Top: Full frame DSLR at 200mm. Bottom: APS-C sensor DSLR at 200mm.

A 200mm telephoto lens gives the same view as a traditional 320mm lens, when the 1.6x crop factor is taken into account – great for getting close to the action in sports or wildlife photography.

Less lens choice
Full-frame cameras used to offer a real advantage when shooting landscapes or indoors in tight spaces. However, lens makers have combated this by developing zoom lenses with shorter focal lengths exclusively for use on APS-C-sensor cameras.

Standard APS-C-style zooms offer an 18mm setting, equivalent to the view given by a full-frame 28mm lens. Super-wide lenses offer settings of 10mm – equivalent to, or with an effective focal length (EFL) of, 16mm. These lenses cannot be used with full-frame cameras (as they would produce dark corners) – so APS-C users actually get a wider choice of optics!

Blurring backgrounds
Portrait photographers love full-frame DSLRs, as the larger the sensor a digital camera uses, the smaller depth of field (DoF) you get. This means that you can throw backgrounds and foregrounds more out of focus – for artistic effect and to draw strong attention to the subject. The reason for this is that the amount of depth of field depends of three different factors: the aperture, the subject distance, and the focal length.

Use full-frame, and the actual focal length you use for a particular composition changes. You use a 28mm lens setting, say, rather than the 18mm you would need with an APS-C camera – and this difference in focal length means less depth of field.

In practice, this means that wide apertures on full-frame cameras provide noticeably more defocused backgrounds than on APS-C cameras. Look at our portrait photos below and you’ll see that a full-frame DSLR at f/5.6 produces a seemingly similar amount of depth of field and background blur to an APS-C camera at f/2.8. The f/2.8 shot on the full-frame DSLR creates a very shallow DoF for knocking backdrops out of focus to make your subjects really stand out from their surroundings.

Top: Full frame DSLR at f/2.8. Bottom: APS-C sensor DSLR at 200mm

APS-C cameras are better, however, if you want to maximise depth of field – which has advantages in studio and landscape photography. For example, when using the same angle of view, on an APS-C DSLRs you will be able to get away with using, say, f/14, whereas on a full-frame DSLR you may have to use f/22 to ensure your scene is sharp from foreground to background.

How to remove dust and imperfections from photos

dcworld — Thu, 21 Jan 2010 12:48:12 +0000

Dust on your D-SLR’s sensor can ruin your image. Watch this video to find out how to use Photoshop’s dust removal tools to get blemish free shots.

No matter how careful you are, dust always seems to end up in the inner workings of your D-SLR. This is most problematic in landscape photography as shooting at small apertures such as f/22 aren’t as forgiving as shooting at, say, f/4. Often the first time you’ll notice these marks appearing on your shots is when you open them up in Photoshop. Most imperfections can be removed using Photoshop’s 3 main dust removal tools, each of which can be used to quickly fix different areas and blemish types. Find out how to use the Spot Healing Brush, the Healing Brush and the Clone tool.