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[Lesson 1] The Charm of DSLR Cameras

The charm of DSLR cameras lies in the expandability of the system and the overwhelmingly high image quality. In this article, let's learn about the characteristics of digital SLRs by comparing them with compact digital cameras. (Reported by: Ryosuke Takahashi)

Completely Different in Expressive Power

Bokeh effect created by a digital SLR camera

The size of the image sensor in an SLR camera is very large compared to a compact digital camera, and this makes it easier to create more significant bokeh effects. A large background blur helps to bring out the main theme.

Bokeh effect created by a compact digital camera

Compact digital cameras, in contrast, have a small image sensor, and do not support exchangeable lenses, making it difficult to create large bokeh effects.

Effect of the image sensor size on the bokeh effect

Besides the outward appearance, DSLRs and compact digital cameras also vary fundamentally in their internal structure. The most distinctive difference is found in the image sensor, the component for receiving light and producing images. While compact digital cameras generally have an image sensor with a size of 1/2 inch, the APS-C format image sensor, which is commonly used on DSLRs, has an area that is approximately 10 times larger. A larger image sensor allows each of the pixels to capture more light, and this also helps to add numerous advantages to the electrical properties, such as a low level of noise. Also, the impression of the resulting image changes drastically with the background blur. In this respect, DSLRs, which allow the lens to be exchanged, are also a notch above compact digital cameras. The difference in the bokeh effect based on the image sensor size also depends largely on the focal length of the lens. If we compare the two images with the same composition, the focal length tends to be shorter (wider angle) when the area captured by the image sensor is smaller. This, in turn, makes it more difficult to create background blur. Therefore, one of the reasons the resulting image turns out very different in the case of a DSLR can be attributed to the size of the image sensor.

Completely different in image sensor size

1: 35mm
2: 24mm
3: 36mm
The area that can be captured by a 35mm film is about 24 x 36mm. The name, "35mm," comes from the width of the film.

1: 24mm
2: 36mm
A full-frame image sensor captures the same area as that of a 35mm film. This sensor can be found mainly on EOS models designed for professionals and advanced amateurs.

1: 14.9mm
2: 22.3mm
This sensor is used on a wide range of cameras, from entry-class to middle-class models. It allows cameras to be compactly designed while producing a high image quality.

1: 4.8mm
2: 6.4mm
Shown here is a 1/2-inch image sensor. For compact digital cameras, CMOS sensors with a diverse range of sizes are employed, such as the 1/2.5-inch and 1/1.7-inch formats.

Image quality is also dependent on the image sensor size

Above is a comparison of the typical image sensor sizes with the 35mm film as the basis. We can see that even for the APS-C format sensor, which is most widely used, the area is sufficiently large, and the difference is evident when compared to the sensor of a compact digital camera. The area of an APS-C size sensor is about 10 times larger than the 1/2-inch sensor used on compact digital cameras. The gap is even wider in the case of a full-frame sensor, which is about 28 times larger. In addition to the larger bokeh effect created by the larger image sensor size, each pixel inside the image sensor is also capable of capturing more light, so the image would appear less grainy (less noise). At the same time, the reproducible gradation range from white to black also widens proportionately with the area captured by the image sensor.

Widening Your Scope of Expression with the Multitudes of Exchangeable Lenses

With over 70 lenses, Canon's EF lens series is one of the top runners in the world's imaging industry.

Potential of your DSLR widens with the number of lenses

Digital SLRs find their origins in film SLR cameras, and are capable of handling different shooting needs with the use of exchangeable lenses. Compact digital cameras, on the contrary, make use of a fixed lens that is not removable, so regardless of how powerful the zoom lens may be, they can never hold a candle to the rich lineup of exchangeable lenses for DSLR cameras. Canon's EOS series comes with exchangeable EF lenses with focal lengths ranging from 8mm to 800mm, and more than 60 different types of variations. These EF lenses are further classified according to attributes such as the lens brightness and characteristics. The charm of DSLRs therefore lies in the ability to make full use of these lens assets, and one of their greatest strengths is that you can capture photos you desire simply by changing the lens, be it a more magnified shot of the subject, or a wide-angle photo that captures the surroundings.

Photo taken using the EF8-15mm f/4L Fisheye USM.

EF8-15mm f/4L Fisheye USM

This lens is able to create a strong perspective effect, allowing for depictions with an angle of view that is wider than what we normally see.

Click here for detailed specification

Photo taken using the EF300mm f/2.8L IS II USM.

EF300mm f/2.8L IS II USM

You can produce breathtaking shots like this by attaching a telephoto lens. It freezes the movement of the subject to produce a sharp depiction.

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Captures the decisive moment

The optical viewfinder helps you to capture the decisive moment

Time lag occurs when you are using a compact digital camera.

When you are taking shots using the LCD monitor on a compact digital camera, the camera is unable to reproduce the movements of the subject in real time. This prevents the photographer from releasing the shutter at the right moment. If you are photographing through the viewfinder of an SLR camera, you would be able to capture the subject at the desired timing.

Fast response capable of capturing fleeting moments

Compared to compact digital cameras, one of the merits in using DSLRs is the short time lag of the camera operations. Many compact digital cameras capture images using the LCD monitor. However, what you see on the screen is, strictly speaking, not the real-time image but the image a moment ago. This is due to the time lag that occurs in reproducing the image electrically. DSLRs, in contrast, make use of an optical viewfinder, which allows you to see the actual image without any delay, so there is no time lag between the movement of the subject and what you see through the camera. Additionally, the autofocus function, as well as mechanisms including that for moving the shutter operate at a much faster speed on a DSLR. These are qualities that help photographers to capture the decisive moments. With a DSLR, you can easily capture shots such as a sports game and the fleeting expression of a portrait subject, which would otherwise be a challenge if you are using a compact digital camera.

Focus your attention continuously on the subject through the viewfinder to capture the right moment.

Ryosuke Takahashi

Born in Aichi in 1960, Takahashi started his freelance career in 1987 after working with an advertising photo studio and a publishing house. Photographing for major magazines, he has travelled to many parts of the world from his bases in Japan and China.