Camera designers have had a field day since the first ‘mirrorless’ models were introduced. The market has now matured to provide an interesting array of body styles that use sensors from tiny 6.2 x 4.6 mm chips to the 36 x 24mm size used in professional DSLRs. There’s a camera to suit photographers at all levels of interest and expertise, from snapshooter to professional.

Why Buy a CSC?


CSCs designed for snapshooters who want better quality than a digicam provides tend to be similar to digicams in styling and operation. (Source: Olympus.)

Many cameras are still designed primarily for snapshooters (and often come in colours other than black or silver). But manufacturers with a serious interest in the market are producing elegantly-designed, superbly-built and highly capable cameras, some of which offer more capabilities than the average professional camera.

If you’re in the market for one of these cameras, you’re probably doing at least one of the following.

1. Looking for lighter, more compact gear, particularly for travelling.

2. Stepping up from a compact digicam in search of better image quality.

3. Upgrading a current system.

4. Wanting to shoot movies in a better way than having to rely on the monitor screen for shot composition.

Whatever the reason(s), you’ll be faced with multiple decisions. Firstly, there’s a much wider range of sensor sizes to choose from. You must also consider the range of lenses available and whether they will meet your requirements, both now and in the future. Finally, you need to see how well the system you choose meets your requirements, both now and in the foreseeable future.

What Makes a CSC?

While they’re sometimes described as ‘hybrid’ cameras, mirrorless Compact System Cameras (CSCs) are different from either compact digicams or DSLRs, but combine some of the benefits of both. Although they share the functionality of interchangeable lenses, CSCs lack the reflex mirror viewing system that distinguishes DSLRs.

Without the reflex mirror, the back of the lens (technically known as the flange back) can be positioned much closer to the image sensor. The resulting cameras can, therefore, be much smaller and lighter ““ and are usually more robust and cheaper to manufacture because they contain fewer moving parts.


The diagram above shows how the distance between the lens flange back can be reduced dramatically by removing the reflex mirror viewing system, leading to more compact camera bodies.

Factors to Consider

Which CSC you choose depends on a number of factors including your photographic expertise, budget, size and weight constraints and how you plan to use the camera. When shopping for a CSC system, the main factors that should influence your choice will be the following:

1. The sensor size and resolution will determine how large you can make prints from your images. If you don’t make big prints and prefer to share your photos online via social networks, these aspects of the camera specifications are probably irrelevant.

2. The size and weight of the system (camera plus lenses). If you want a more compact travel kit, this should be your main focus (although other factors should also be taken into account).

3. The availability of lenses for the system. This factor could be a deal-breaker for serious photographers as the lack of wanted focal lengths and special purpose (e.g. macro) lenses will be unacceptable to many.

4. Connectivity could be a key differentiator between products for ‘connected generation’ buyers and photographers who rely extensively on cloud storage. It will be important to examine the extent to which a camera can be interfaced with a smart-phone and the amount of support it provides for easy uploading to the internet for various end uses (including remote storage and printing).


An example of the type of image that can be made with a CSC. This scene at Sossus Dunes in Namibia was photographed with an Olympus OM-D E-M5   camera and M-Zuiko Digital 75-300mm f/4.8-6.7 II lens. The shot was taken about 30 minutes before sunset using a focal length of 300mm and ISO of 320. The exposure was 1/250 second at f/10. No filters or additional digital effects were used.

Sensor Size & Resolution

All things being equal, a larger sensor should be preferable to a smaller one. But things are seldom equal and you are buying more than just a sensor. All the components in the system ““ camera body, lenses, flash, remote controls, batteries and other accessories will influence your choice. So should the image processor in the camera.

High resolution isn’t the most important criterion for selecting a camera system. All cameras (as distinct from mobile devices) with resolutions of 12 megapixels or higher can deliver high enough image quality to produce poster-sized prints ““ provided they are used correctly. There’s not much sense in paying for more resolution than you require.

CSCs come with different sensor sizes that have more influence on the size of the camera body and lenses than on practical imaging performance. Five main sizes are available, as shown in the graphic on this page.


This graphic illustrates the relative differences in sensor sizes for CSCs.

Sensor size can influence image quality, although mainly at high sensitivity settings. Larger sensors can accommodate larger photosites which actually capture the imaging light. The bigger the photosite, the more light it will capture per pixel. More light equates to better performance, particularly at low light levels. The table below lists the main sensor dimensions and shows which manufacturers have products in the various sensor sizes.


* for 16-megapixel resolution
 ** The NEX brand name was discontinued in early 2014 and all Sony interchangeable-lens cameras now bear the Alpha brand name.

Image Processors

The image processor chip that handles the data coming from the sensor will also impact upon the camera’s performance and functionality. It’s difficult to compare image processors, but ““ in most cases ““ newer processors use more powerful and efficient algorithms that enable them to handle image data faster and more effectively. Improvements you can expect from the latest processors include:

Faster continuous shooting speeds with larger buffer memories to support longer bursts of continuous shots;

Improved autofocusing performance;

Reduced noise in shots taken at high ISO settings, particularly with slower shutter speeds;  

Improvements to movie recording capabilities.

System Size and Weight

Removing the reflex mirror assembly enables manufacturers to design and make camera bodies that are significantly smaller than the average DSLR. But there’s still a wide disparity in the sizes of different camera systems. In most cases, this relates directly to the size of the image sensor.

‘Full frame’ CSCs are the largest and heaviest CSCs because they have the largest sensors and use bigger, heavier lenses.

Stepping down to systems based on APS-C sized (~23.6 x 15.6 mm) sensors provides some reduction in the size and weight of both cameras and lenses. However, where the system depends on existing DSLR lenses to fill in gaps in the lens focal length range, there won’t be much reduction in the size, weight and cost of the lenses needed to support it.

Currently, the most compact and lightest systems that provide the performance required by serious photographers are those using the Micro Four Thirds (M4/3) format. Their smaller sensors require smaller lenses, which are lighter because less glass is needed to make them. (This can also reduce their cost.)

M4/3 currently offers more than 40 different lenses to go with a total of 33 cameras that have been released since the system was introduced in 2008.

The Nikon 1 sensor is smaller than M4/3 and this system has even smaller, lighter lenses. When we went to press, the design of the cameras in this system was more suitable for snapshooters than serious photographers. As of mid 2014, the highest resolution to date was 14 megapixels, the maximum sensitivity supported was ISO 6400 and so far there are 11 lenses in the system.  

Being based upon a digicam sensor, the Pentax Q system currently offers the smallest camera bodies and lenses. Its lens range is limited and imaging performance is not significantly different to a similarly-specified Pentax fixed lens digicam.


Some M4/3 cameras look like small DSLRs and include similar user-adjustable control settings and accessories. (Source: Olympus.)


Cameras with larger sensors, such as the Sony ?7 shown here, use larger and heavier lenses than those with smaller sensors. (Source: Sony.)


Excerpt from  Compact System Camera Guide.