DSLR Camera Buying Guide

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DSLR Camera Buying Guide

DSLR or Digital Single Lens Reflex cameras are a significant upgrade over point-and-shoot compact cameras. While the cost can be quite steep, the trade-off in terms of quality, durability, and speed makes up for the high price. DSLR cameras are used in almost all professional settings nowadays and are becoming increasingly popular among amateurs.

About DSLR Cameras

The Single Lens Reflex (SLR) camera assembly was developed in the middle of the last century. In a SLR system, light passing through a lens strikes a mirror angled at 45 degrees and bounces up to the viewfinder for framing shots. When the shutter is pressed, the mirror flips out of the way to allow the light to strike the digital sensor. It is a fairly uncomplicated assembly that has remained essentially unchanged over the last fifty years. Earlier SLR cameras utilised film but have been phased out in favour of digital sensors.
DSLR cameras have interchangeable lenses, that is, the cameraman can attach a variety of different lenses to produce the best possible results. The quality and type of lens affects the amount of light reaching the viewfinder via the angled mechanical mirror. Most DLSRs use pentaprism mirrors, although a few entry level models might utilise pentamirrors made from plastic instead. It is possible to alter the focus manually when framing the shot – which is a significant advantage over compact digital cameras – by adjusting the lens. Once the shot has been framed, clicking the shutter moves the mirror out of the way, allowing light from the lens to strike the sensor. After the picture has been taken, the mirror moves back into place for framing another shot – a process that takes less than a second in most cameras.
Images produced by DSLR cameras are noticeably better than those produced by compact digital cameras, especially in low light conditions. This can be ascribed to the quality of interchangeable lenses, SLR assembly, and digital sensor. DSLR cameras are also significantly faster than compact cameras, which makes them perfect for capturing objects in motion – that is, in sports and wildlife photography. Further, DSLR cameras can be upgraded with a variety of accessories and are designed for professional use in challenging environments.
Canon and Nikon are the two most popular DSLR camera brands and command over 97 per cent of the market share. Sony, Pentax, and Olympus are other prominent DSLR camera manufacturers.

Buying a DSLR Camera

DSLR cameras differ widely in quality, durability, and price. They might also utilise different sensors, image stability systems, and shutter mechanisms which ultimately affect the quality of the image produced. Newer cameras also have a range of digital features such as face detection, smile detection, red-eye correction, etc.

Types of DSLR Cameras

A DSLR camera may have interchangeable or fixed lenses. They can also differ according to the shooting mechanism employed – SLR or SLT. A brief overview of the various types of DSLR cameras can be seen below:


Interchangeable Lens DSLR

The capability to change from a telephoto to wide-angle or fisheye lens is highly desirable. Interchangeable lens DSLRs are often referred as True DSLRs.


Fixed Lens DSLR

These cameras have a fixed factory-fitted lens. This hampers flexibility and image quality, but also reduces cost.


DSLT (Digital Single Lens Translucent)

SLT cameras utilise the same shooting mechanism as SLR cameras but with a crucial difference – the mirror is 100 per cent fixed and translucent, not reflective. Thus, light coming in from the lens is distributed equally between the viewfinder and sensor. Sony is the only manufacturer of SLT cameras.


DSLR Camera Sensor Size

The size of the sensor affects the kind and quality of images that can be taken by the DSLR camera. Larger, full-frame sensors are expensive but offer considerable advantages in terms of depth of field and flexibility. The size of the captured image area decreases with the size of the sensor. Thus, with smaller sensors, the captured image appears as if it was taken at a greater focal length. Depth of field, consequently, is compromised.
An important consideration when choosing sensor size is crop factor. Full frame sensors have a crop factor of 1x, that is, it captures the entire 35mm field of view from the viewfinder. APS-C cameras have a crop factor of 1.5x or 1.6x, which means they capture an image cropped by a magnitude of 1.5x. DSLR cameras typically have one of the three sensor sizes:


Full Frame

A full frame sensor is the same size as a 35mm frame. Consequently, cameras with full frame sensors are fully compatible with older film-based SLR camera lenses. The captured image does not get cropped, and consequently, the camera has a much better depth of field. As a downside, full frame cameras tend to be expensive.



APS-C is the most common sensor size. The crop factor is between 1.5x or 1.6x, producing an image that appears as if it was taken at a longer focal length. On the positive side, both APS-C sensor cameras and their lenses are cheaper.



Four-Third sensors have crop factor of 2x, further reducing the depth of field. Four-Thirds sensor cameras are cheaper than APS-C models and very portable although they suffer from poor image quality, especially in low-light settings.


DSLR Camera Viewfinders

The viewfinder is the part of the camera that is used to compose and focus an image. In DSLR cameras, the sensor and viewfinder are part of the same assembly, with a mirror modulating light from the lens. Theoretically, the viewfinder shows the exact image that will be taken by the camera. In practice, viewfinders can vary in accuracy, which can affect the quality of the finished image.
There are three types of viewfinders used in DSLR cameras:

Optical Pentamirror Viewfinder

An optical pentamirror viewfinder utilises an assembly of three mirrors to correct and capture the upside-down image coming from the lens. Pentamirrors are cheap and lightweight but produce duller, darker images. Pentamirror viewfinders are typically used in entry-level DSLRs.


Optical Pentaprism Viewfinder

An optical pentaprism utilises a five sided prism to reflect the image coming from the lens. Pentaprisms are expensive and heavy but are also brighter and more accurate than pentamirrors. Most mid to high-range DSLR cameras utilise pentaprism viewfinders.


Digital/Electronic Viewfinder

An electronic viewfinder projects a video feed of the images captured by the lens onto the viewfinder. There are no mechanical moving parts or mirrors. The image quality is poorer than pentaprism optical viewfinder, but usually better than pentamirror viewfinders.


DSLR Camera Image Stabilisation

Any movement of the camera when a picture is being taken can cause the image to appear blurred or noisy, especially in low-light conditions. To reduce camera shake, DSLR cameras utilise some sort of image stabilisation system. Image stabilisation may be advertised as anti-shake, vibration-reduction, etc., depending on the manufacturer. Image stabilisation can be digital, optical, or sensor based. A brief overview of these three techniques can be seen below:


Optical image stabilisation utilises gyroscopes built into the camera lens to reduce camera shakes. Stabilised lenses tend to be expensive, however, making optical image stabilisation an efficient but expensive choice.



Sensor image stabilisation works on the same principle as optical systems, except that the image correcting gyroscopes are built into the camera sensor itself. Consequently, it is possible to take advantage of stabilisation features even with ordinary lenses which reduces overall costs.



Digital image stabilisation systems alter the image to reduce blur and noise after it has been captured. Digital stabilisation systems can reduce image quality and are usually found only in entry-level DSLRs.


Additional Considerations When Buying DSLR Cameras

Besides the viewfinder, sensor, and image stabilisation systems, there are a few additional factors to consider when buying a DSLR camera. These include:

DSLR Camera Size

DSLR camera size affects its portability and ease of use. Most entry-level DSLR cameras aimed at amateurs sacrifice features in favour of portability. Professional grade cameras not only utilise larger components and assemblies (pentaprism viewfinders, interchangeable lenses, full frame sensors, etc.) but usually also include waterproof and dustproof casings. Besides size, DSLR camera weight must also be considered before making a purchase decision.

DSLR Camera Speed

Camera speed refers to the number of pictures that can be captured per second by the camera. Faster cameras allow the photographer to capture as many as 10 frames or images per second. Speed is an important consideration for professional photographers who often have to take multiple shots of the same subject in succession. Most entry-level DSLR cameras have a speed of 4-5 frames per second. Professional grade DSLRs can shoot upwards of 10 frames per second. Professional DSLR cameras also come equipped with a Continuous Shooting Mode or Speed Burst Mode that allows the photographer to hold the shutter to take photographers continuously – a requirement for capturing sporting events or wildlife.

DSLR Camera Megapixel

Megapixel (MP) count refers to number of pixels that make up an image. All other things being the same (sensor quality, lens, light conditions, etc.), the higher the MP count, the better the image quality. Megapixel count isn't nearly as important a consideration in DSLR cameras as in point-and-shoot cameras. Most DSLRs sold today have at least 8 megapixels, which is more than enough for most casual and professional purposes. Higher megapixels (> 8MP) are useful for top professional photographers working with huge prints. For others, any DSLR with an 8MP count is will suffice. Sensor and lens quality have a much greater role to play in determining final image quality megapixel count.


Digital SLR cameras offer superior image quality, expandability, and control over compact point and shoot cameras. Since DSLR cameras are an expensive purchase, several factors must be considered before making a purchase decision. The type of sensors, lenses, and viewfinder technology employed can affect final image quality. Additionally, ease of use, camera size and durability, megapixel count, and shutter speed are important considerations for finding the right DSLR camera. eBay is an excellent marketplace for buying DSLR cameras, with an extensive range of offerings at affordable prices.

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