Today’s Question: I’m constantly hearing about the advantages of mirrorless cameras compared to digital SLRs. But do those advantages still apply when the mirrorless camera is full-frame? Isn’t it then just as big and heavy as an SLR?
Tim’s Quick Answer: There is no question that mirrorless cameras provide some advantages (along with some potential disadvantages) compared to single lens reflex (SLR) cameras. In most cases, however, the size and weight benefits don’t relate so much to SLR versus mirrorless, as they do to the size of the image sensor used in the camera.
More Detail: Mirrorless cameras are often touted as being smaller and lighter than a digital SLR. However, just because a camera is mirrorless doesn’t mean it will necessarily be smaller or lighter than an SLR camera.
The fundamental difference between a mirrorless camera and an SLR is, of course, the absence of the mirror that is used to enable an optical through-the-lens viewfinder. While there is a degree of weight savings to be gained by the absence of these components, mirrorless cameras gain much of their size and weight advantage from the use of a smaller sensor size.
With a smaller image sensor a camera can employ smaller lenses to achieve the same field of view. Thus, the camera body can be smaller and the lenses can be smaller. The smaller size of both generally translates into lighter weights.
Of course, digital SLR cameras are available with a variety of different sensor sizes, which translate into varying sizes and weights. For example, a small digital SLR that uses a sensor smaller than a “full frame” digital SLR could be lighter (and use smaller lenses) than a full-frame mirrorless camera.
I think it is important to keep in mind that mirrorless cameras aren’t simply digital SLR cameras with the mirror removed. The absence of a mirror provides a variety of advantages, such as excellent continuous autofocus performance even during capture.
I think it is a mistake to seek out a mirrorless camera under the assumption it will automatically be smaller and lighter than all available digital SLR cameras. However, I do think mirrorless cameras offer a variety of advantages that go far beyond size and weight, and are therefore worth exploring. I most certainly don’t feel it makes sense to choose mirrorless versus SLR based purely on the category these cameras fall into. Rather, the specific features of individual camera models should be evaluated to find the best fit for your specific needs.