The Mirrorless DSLR – a new class of digital camera?

What is meant by the somewhat contradictory term ‘Mirrorless DSLR'?

The basic idea seems to be quite simple and obvious: let’s get rid of the bulky mirror and pentaprism but retain all the main advantages of a DSLR camera such as the interchangeable lens systems, large size image sensors, advanced picture processing, etc.

This should make it possible to build much smaller and lighter digital cameras that would be capable of producing picture qualities equal to DSLR cameras of the same level.

And this is exactly what Olympus and Panasonic have done when they implemented the Micro Four Thirds System. The idea seems to be so convincing that Samsung has already launched its own version, the mirrorless Samsung NX-10 camera and other manufacturers such as Sony appear to be ready to enter the potentially lucrative market for mirrorless DSLR cameras or "Digital Interchangeable Lens system" cameras as Olympus and Panasonic prefer to call them.

Of course, there are also the Leica M8 and M9 digital rangefinder cameras that even offer a full frame sensor in the Leica M9 combined with their excellent M lens system, but this at a much higher price reflecting their top level of quality.

The new mirrorless systems, however, are aimed at the broader consumer market and have a much lower price tag.

What are the advantages of mirrorless DSLR cameras?

As already mentioned, the main advantage is probably that much smaller and lighter cameras can be build with practically the same functionality and picture quality as DSLRs. In addition, the reduction in mechanical parts may make them more robust and it is also easier to implement HD-quality movie functions in such cameras.

The mirrorless cameras from Olympus and Panasonic are based on the Micro Four Thirds System that uses a sensor the same size as in their larger DSLRs (standard four thirds system). The difference is that in the Micro Four Thirds System the length of the flange back (distance between lens mount and sensor) could be reduced by half, as the space for the mirror is not longer required. In addition, the diameter of the lens mount could be reduced by about 6 mm, which makes it possible to design much smaller lens systems while offering the same image quality.

What are the disadvantages of mirrorless DSLR cameras?

Without the mirror it is, of course, no longer possible to view the scene directly and without delay through the front lens. For some applications this could be seen as a disadvantage (e.g. fast moving sports photography) and some purists may just prefer the clear direct optical view through the lens and don’t mind the extra bulk.

In mirrorless cameras, the scene may be viewed on the inbuilt screen in 'Live View' (which can be awkward in bright daylight), through a separate optical viewfinder (has to be matched to the particular front lens) or an electronic viewfinder (which may be inbuilt or supplied as optional accessory). Different manufacturers offer different solutions.

With electronic view finders (EVF), the scene is displayed on an internal LED screen after it has been electronically converted from the image projected through the front lens onto the image sensor (but this with a slight delay).

Another possible disadvantage is the available focusing system. DSLR cameras can use the fast and accurate phase detection autofocus system. Mirrorless cameras use contrast detect autofocus systems which tend to be slower. This can be problematic when shooting fast moving scenes.

The Mirrorless DSLRs available on the market

The mirrorless DSLR or rather 'Interchangeable Lens' cameras offered by Olympus are the Pen E-P1, which is going to be replaced by the Pen E-PL1 and their top model, the Pen E-P2 which addresses some of the shortcomings of the original P1. They are designed in attractive retro style with a compact body resembling the legendary original PEN from Olympus.

They are all based on the Micro Four Thirds System and use the same 4/3" Hi-Speed Live MOS sensor with 12.3 effective Megapixels. They all can use the same lens system and can also use the larger standard four third lenses with an optional adapter. All have sensor shift image stabilization, ultrasonic dust reduction and HD video recording with max. 1280x720 at 30 fps. However, the available recording time seems to be somewhat limited.

This means that you could expect the same picture quality when using the same lens on all three cameras especially when shooting in RAW format. The only real differences seem to be an additional accessory port offered by the P2 that allows, for instance, the attachment of an articulated electronic viewfinder - and the PL1 has an inbuilt flash. All three measure about 120x70x35 mm with a body weight of 300 to 335 g.

Panasonic offers it’s LUMIX G system with the DMC-G1, the new G2, the new G10 and the GH1 which are styled similarly to DSLR cameras in smaller bodies (124x83.6x74 mm, 385g) and the DMC-GF1 which features a very compact and light body (119x71x36.3, 285g). Also Panasonic is using the Micro Four Thirds System, which means that the cameras are compatible with the lenses of this system (standard 4/3 lenses can be used with an adapter). In addition an adapter for the high-quality Leica M system lenses is available!.

All models have 12.1 megapixels Live MOS sensors, a large 460,000 dot LCD screen, inbuilt flash and HD movie mode (not in DMC-G1) at 1280x720 and 30fr/s. The larger models have inbuilt Live view finders (an optional accessory viewfinder is available for the GF1). The new G2 offers a Free angle LCD with touch screen and the GH1 is geared towards HD video recording offering 1920x1080 full HD at 24 fps and 1280x720 at 60 fps. Image stabilization O.I.S. is implemented in selected lenses.

Samsung has recently launched it’s version of a mirrorless DSLR – the Samsung NX-10. Samsung is not using the Micro Four Thirds System but a APS C sized image sensor which is 1.5x the size of the 4/3 system. The camera has an inbuilt electronic viewfinder (EVF) and is styled resembling a small version of a DSLR. In addition, the image can be viewed on a the high resolution 3.0” AMOLED screen in ‘Live View’.

Also Sony has now joined the mirrorless club with a new addition to its alpha range. The Sony alpha interchangeable system cameras NEX3 and NEX5 are supposed to have a APS-C sized image sensor and offer up to full HD 1080p video recording in the NEX5!

If size is your main concern (and this is probably the main advantage of the mirrorless systems), the smallest camera currently available would be the Panasonic Lumix GF1 with inbuilt flash, closely followed by the Olympus PEN models. If size is less important you may go for the larger models for some added functionality, but then you could also consider the standard DSLR cameras which may be available at cheaper prices and uncompromising functionality. If you can afford it, you may use a full DSLR camera for your standard work and a second mirrorless DSLR as a more mobile, but quality option when a larger camera could be a hindarence.

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