Monday, 30 July 2012

Will mirrorless cameras replace DSLRs?

You keep hearing these days that mirrorless cameras will replace DSLRs. Whether they do so will depend upon a number of factors.

Back in the days of film cameras, compacts never replaced SLRs. When you have the same imaging size, then the interchangeable lens is likely to be the biggest component in your equipment; any size advantage you may have purely on the camera body is likely to disappear. An attempt to make the camera body smaller while maintaining image size, requires reducing the lens flange focus distance which results in a reduction in image quality on the digital format due to loss of tele-centricity. Of all vendors, Nikon and Olympus seem to have recognised this issue. Olympus four-thirds design touted the benefits of tele-centric design of their lenses. So it seems that small size and great quality do not always go together.

It is possible to overcome the issues caused by short flange focal distance, firstly by designing sensors that allow for this, and secondly by using software to correct certain aberrations. The micro four-third implementation appears to rely heavily on software based correction. Leica M9 and Ricoh GRX cameras employ corrections at the sensor level as well, by using modified on-chip micro lenses. Eventually software based corrections may become perfectly acceptable, reducing the need for perfect optical performance. On the other hand the increase in sensor resolution will place more demands on optical performance; it remains to be seen whether systems relying on software based corrections can perform equally well or surpass those that inherently produce better results due to tele-centric design.

The through-the-lens view that an SLR offers has always been its strength. I remember the first time I used an SLR camera how astounded I was by the view, having previously used a compact film camera. To be able to the see the image as it would appear on film, to see the subject move in and out of focus, was exhilarating. Some of that pleasure has been forgotten even in the DSLR world as cameras with APS-C sensors often come with low magnification viewfinders, and focusing screens are no longer designed keeping the manual focusing requirements in mind. The mirrorless format, unlike the compact cameras of old, however can take on this challenge using high resolution electronic viewfinders. The EVF has an added advantage - the image can be magnified if required - and assuming that technology will eventually allow an electronic viewfinder to be superior to an optical one in terms of latency and low light performance, then it seems that the SLRs will eventually lose any advantage they have in this area.

Perhaps the last advantage SLRs have is their ability to use phase detection in autofocus. But the advent of Nikon 1 cameras indicate that this technology may well end up with mirror less cameras as well.

I personally think that the demise of the SLR is inevitable. Back in 2003 I wrote:
What I would like to see is for Nikon to take another bold step and get rid of the mirror from the SLR. Ofcourse, the name SLR would have to be dropped. With a good EVF, this seems to be the next logical step. It will allow Nikon to provide must faster framing rates, and will also enable better optics. If they could do this and still keep the F mount and backward compatibility ...
I have a feeling that while the DSLR may disappear, Nikon and Canon's SLR systems will live on. These two companies must already be working on cameras that will remove the mirror but work on their existing mounts/lenses. In fact, I had expected the Nikon D4 to feature the Nikon 1 on-sensor phase detection technology; it did not happen but surely its only a matter of time.

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