Over this past winter I received a question in my Inbox from a photographer regarding mirrorless cameras. It has been a while since our communication, thus my answer is slightly updated to reflect my current information/kit. I was given permission to use this exchange on my blog so that others in a similar situation might benefit:

Question:

Tom,
I located your web site while surfing for mirrorless camera related reviews. I am a part-time semi-pro photographer in North Carolina and currently shoot all Canon, 5D II, 6D, 24-70 2.8, 70-200 2.8, 50 1.4, 85, 1.8 and 24-100 4.0. I shoot mainly family, senior portraits, engagements and a few weddings. I am a longtime shooter but in the past 7 months have taken my photography more seriously. I would like to train my wife to be my 2nd shooter for weddings but camera size and weight is a major problem for her. I am interested in the mirrorless cameras but don't want to invest in another form factor due to infancy of the technology. I would love to hear your opinion and what mirrorless camera and starter lens you would recommend. I have been researching the Fuji and Olympus OM-D EM-1. I love my Canon 6D but it is still large for my wife's hands. Thanks for any advice and I love your work. --Cecil

Answer:

I am not a wedding shooter, but I would assume that your (and your wife's) priorities, other than size/weight, is low-light performance and focusing capability (especially in low-light).

There are various choices from Panasonic, Olympic, Fuji, and Sony--each with their strengths and weaknesses. You say you have been researching Fuji and Olympus.

All things considered, if it were me, I'd definitely take a serious look at the OMD EM1 that you mention. Not because I currently use Olympus (I used to shoot Canon full frame as well), but because I believe it to have the fastest and most accurate autofocus [UPDATE: I would put the Panasonic GH4 up there with top-notch, near-instant focusing, and even in dark situations. But only if you need great video capabilities and don't mind the non-rangefinder shape/size]. And you know that cameras are worth nothing if you can't get a consistent and quickly-focused shot. And I'm not talking just fast--but blazing fast, easily matching DSLR and sometimes beating it in single-shot autofocus lock. What the EM1 has now (over 2012's EM5) is phase detect autofocus embedded on its sensor, so it can now reliably track in continuous autofocus. Panasonic does not yet have this [UPDATE: the Panasonic GH4, however, has a new proprietary processing/focusing algorithm called "Depth-From-Decfocus" that in my early, non-scientific testing seems to be decent with continuous autofocus--currently only working with Lumix lenses], Fuji just started to incorporate this, but their autofocus in general is rather sluggish compared to Olympus (I've tried Fujis when I had also considered them). Sony, I don't have much experience with other than messing around with their latest A7 and A7R full frame sensor cameras at the store. Even Sony's autofocus doesn't feel as fast and responsive, especially in low light. The full frame is nice, though. I'm still testing them out [UPDATE: Reports on the web indicate the new Sony A7S is rather good at focusing in low-light].

As far as ergonomics: again, I feel Olympus handily beats them all, and it's closer to DSLR ergonomics (with its grip and button placement) than the other range-finder styled mirrorless cameras. It is also very customizable--a big plus. The only other mirrorless camera with a more DSLR-like look/feel is the Panasonic GH3/GH4, but it doesn't have in-body image stabilzation, and it's huge/heavy (it's the size of a regular DSLR--probably not what your wife wants). [UPDATE: The GX7 is the first Panasonic micro 4/3rds body with built-in image stabilization.. Though not 5-axis, it seems to be pretty good according to photographer Tyson Robichaud at his comparison blog]

Speaking of in body image stabilization--Olympus's is leading class, and still the only stills camera manufacturer with 5-axis correction. I would imagine this is huge for weddings in low-light.....especially if your wife doesn't intend to use a tripod. I'm talking hand-held sharp exposures easily in the 1/2 second range, and it's not uncommon to find people being able to take 1-second hand held!! My personal record is about 1 1/2 seconds if my technique is really good. This is amazing technology, and coupled with a fast prime lens you don't have to every worry about raising your ISO into questionable range again.

And speaking of lenses--assuming that you will go the micro 4/3rds route--there are plenty. M43rds has the most developed system of all mirrorless, which is another reason why I chose it over the other mirrorless systems.

For starters, I recommend some of their primes since they are very fast, light, and tiny (good for portability and weight). Remember, because of the crop factor, you would multiply the lens mm by 2 to get the full frame equivalent. For example, 25mm on micro four thirds would give you the same viewing angle as a 50mm prime on your Canon.

I'd recommend:

Wide angle: Panasonic 14mm/2.5 pancake lens (very tiny), about $150 if you search around on ebay or used. If you want to go premium quality, then Olympus 12mm f/2.0 prime lens. It's sharper, faster, but costly at between $700-$800.

Normal(ish) viewing angle: Olympus 17mm/1.8, about $400. Panasonic 20mm/1.7, about $300-$350. Both of these lenses are tiny. Panasonic 25mm/1.4 is bigger and heavier, but it is Leica branded and is an unbelievable lens with great bokeh. That goes for about $400-$600 (price fluctuates). Panasonic just came out with the new 15mm/1.7 Leica prime lens, rather pricey at about $600 brand new.

Portrait/short tele: Olympus 45mm/1.8. $400. I've said it time and time again, this is the best bang-for-the-buck lens for micro 4/3rds. It's tiny, light, razor sharp wide open, and delivers great bokeh. Its premium competitor is the Panasonic-Leica 42.5mm/1.2 Nocticron lens with built-in stablization and the fastest-aperture lens with autofocus . This lens is extraordinary [see my initial impressions blog, my first lens comparisons blog, and my photoshoot blog with it], but very pricey at $1500-1600. It's not recommended if you're merely dipping your toes into this system to give it a try. I have both the Oly and Panny; they each serve their own purpose. The other premium option here is the Olympus 75mm/1.8, but it's $800-$900. Which is great if you have the distance to work with it, but even I end up using the 42.5mm/45mm much more in my shoots than with the 75mm.

Thank you, Cecil, for your question and for reading the blog! :)