6 November 2012
Compact System Cameras
For a long time the digital SLR has been seen as the only way to go if flexibility and high quality images are required. The wide range of optics available usually means that the right lens could be found for a particular task. The downside to the DSLRs in general is that they are usually seen as too big and heavy to be seen as convenient and as a result some people end up leaving their DSLR at home unless they have a specific purpose to bring it with them.
A relatively new sector of the camera market is the Compact System Camera (also known as ILC). These cameras often have a very similar feature set to a DSLR camera in that they have the full range of exposure modes and also interchangeable lenses.
The typical CSC camera is usually much lighter and smaller than the DSLR but they are not usually pocketable. They reason for this is the lenses. The lenses may be smaller than the DSLR equivalent but they may also be optically slower. In general the larger the image sensor in the camera is the larger the optical a will have to be.
Unlike the DSLR where the image sensor is usually either a full frame size or APS-C size, compact system cameras have image sensors of various sizes.
The Pentax Q series of system cameras have the smallest sensor which is not too dissimilar to that used in compact cameras. As a result the Q series cameras are very small. Although the full range of exposure modes are provided getting a shallow depth of field is more of a challenge.
Nikon 1 Series: These cameras are based around a 1 inch sensor. The camera bodies are small and so are the current range of lenses.
Olympus PEN Series: Based around the micro 4/3 specification. The image sensor is smaller than APS-C but larger than a 1 inch sensor.
Panasonic G Series: Based around the micro 4/3 specification. The image sensor is smaller than APS-C but larger than a 1 inch sensor.
Canon M Series: Based around the APS-C image sensor.
Fujifilm X Series: Based around the APS-C image sensor.
Samsung Series: Based around the APS-C image sensor.
Sony NEX Series: Based around the APS-C image sensor.
There are three main formats used for saving images; JPEG, TIFF and RAW. All these formats have their advantages and disadvantages.
The JPEG (.jpg) is a compression format that produces image files of relatively small sizes. The greater the compression the smaller the file size but the lower the image quality.
The TIFF format produces much larger files than the JPEG but (even when compressed). It's main advantage is that there is no image degradation which makes it handy for making large prints. It's disadvantage is that as the resolution of the image sensor increases (increased megapixels) the more unwieldy it becomes to handle tiffs. As a result, the number of cameras with this format is in decline.
The RAW format is not a strict format as it varies with the camera manufacturer. Here are a few names;
- Canon: CR2
- Nikon: NEF
- Pentax: PEF
- Sony (Alpha): ARW
- Olympus: RAW
These formats basically record the original data produced by the imaging sensor. The fact that the original data is recorded means that the very best image can be reproduced that the camera is capable of. Unfortunately, this format requires the use of an application that can convert the data back into a viewable image. Once converted, RAW will usually produce a much more detailed and dynamic image than that derived from a JPEG produced in camera.
PASM (Program, Aperture, Shutter, and Manual) models are standard on compact system cameras. Therefore full creative control is possible as can be achieved on DSLR cameras. The amount of depth of field will be dependent on the size of the image sensor. The larger the sensor the shallower the depth of field can be. The maximum usable aperture will be dependent on image sensor pixel size as the smaller the pixel the sooner diffusion sets in (whereby the image quality starts to degrade as the aperture gets smaller). May be an issue for cameras with a very high resolution image sensor or a very small sensor. As the sensors for compact system cameras are typically smaller than the 35mm formal they inherently has getter depth of field and as a result the very small apertures required on 35mm format (full frame) cameras is not usually necessary to produce a particular depth of field.
The standard autofocusing technology is contrast detection as the focusing is carried out by the image sensor. Contrast detection was notoriously slow in comparison to phase detection AF used in DSLRs but they have improved over time to the but they are quite rapid. Contrast detection AF can be susceptible to hunting as the technology is not capable of determining if a lens is front or back focused. The advantage of CDAF is that focusing is usually very accurate.
Some cameras like the Nikon V series and the Sony NEX series have started to introduce hybrid AF systems whereby the camera can make use of the faster PDAF and maintain the accuracy brought by CDAF.
LCD Monitor / Electronic Viewfinder
This is usually the prime method for composing images with a typical size of around 3 inches. The higher the resolution of the LCD display the easier it is to check critical focus. Just like with compact cameras the LCD display shows all the relevant exposure information as well as the shooting mode.
The LCD monitor comes into its own when it is an articulating design which allows a camera to be held above the head, below the waist and at awkward angles whilst still being viewable.
The LCD monitor forces the camera to be held away from the body which is likely to feel less stable than with the camera held close to the body and up to the eye. Some cameras such as the Fujifilm X-E1, Sony NEX 7 & 6, Nikon 1 V1, Panasonic GH3, Olympus E-M5 etc have built in electronic viewfinders. They can show as much exposure information as a LCD monitor although some cameras have the option to keep the information to a minimum to avoid undue distraction. Unlike an optical viewfinder it is possible for the electronic viewfinder to instantly show the effects of adjusting the aperture so that depth of field can quickly be evaluated.
Electronic viewfinders have been around for a while (certainly since the Minolta A1 hybrid camera back in 1993) and their performance and resolution have steady improved. Despite the improves movements some may still favour having an optical viewfinder.
For cameras without a built in electronic viewfinder there may be the option for attaching an external one. Cameras like the Sony NEX 5R and the Panasonic Lumix GX1 have taken this approach.
Not all CSCs have a built in flash unit. The ones that do have a flash unit that may not offer power any greater than that provided for DSLRs but are still useful for fill flash applications. External flash units are the better option if more power is required.
The lenses are typically smaller and lighter than that crafted for DSLRs in order to match the light weight camera bodies. However, the large the image sensor a camera uses the larger the optics need to be. The compact system cameras with the largest lenses tend to be those using an APS-C image sensor. Also the faster the optical speed of the lens the larger the lens needs to be. The micro 4/3 format makes use of the limitations to produce optics that remain relatively small but with a fast aperture.
Image stabilisation is a must in the modern era. The technology may either by built into the lens or directly into the body. In body stabilisation has the advantage that any lens attached gains image stabilisation.
Lens with built in stabilisation tend to be a bit heavier and larger to accommodating the stabilising lenses. The image stabilisation is optimized for the particular lens.
The Compact System Advantage
The compact system cameras offer many of the advantages of the larger DSLRs but will less bulk and weight. The lens selection generally is not as extensive as can be found for DSLRs but they have been around far longer. This situation is improving with lenses being produced for the most important optical ranges. Where the compact system cameras may lag behind is in their autofocus performance as they are currently not capable of keeping up with high speed action. For other tasks the CSCs are highly capable and may become the preferred choice to pack for travel as a camera body and a number of lenses would take up minimal space.