There you are, sitting around with a stack of APS-C cameras and a bigger stack of micro four-thirds cameras with glorious, jewel-like lenses, and in the back of your mind, no matter how logical you are and no matter how many times you've proven to yourself that your selection of cameras does exactly what you want it to do, you start to think you just might really need a full frame camera. You know, mostly for those times when you'd really like that depth of field to be......tiny. For those portraits like the one above that was done with some sort of esoteric, ultra fast 85mm lens on some splendid, old 35mm film camera. Maybe you were digging through boxes of prints and some random image just grabbed you by the short hairs and made you uber nostalgic for a look you thought you'd have gotten over by now.
We'll leave out whatever personal or psychological reasons might be driving you to even consider getting back into that full frame....situation and we'll consider the whole exercise to be entirely hypothetical, Okay? This isn't (necessarily) an admission that as soon as I finish typing that one of us might be jumping up, grabbing the credit card and the car keys and heading out to acquire one of the cameras under discussion. Rather it's intended as a high minded discussion of the various attributes of three different cameras that might appeal to someone who might be considering adding a bit to the kit.
Just above I mentioned that I was thinking of three different cameras. That's because, to my knowledge, there are just three that can be purchased brand new for under $2,000 each. The candidates I want to discuss are: The Sony A7, The Nikon D610 and the Canon 6D. All three feature full frame, 35mm area, sensors but all three of them are different enough so that a person with no allegiance and no ties to any particular brand might have a hard time choosing.
When I look at them this is what I see:
The Sony A7 is the odd man out. This is because the camera is designed as a compact, mirror less design and uses contrast detection auto focus. The pros of the camera are (because of its shallower dimension between lens flange and sensor plane) its ability to use just about any full frame lens from any system and from just about any decade. At one point I fantasied about buying the camera along with a Nikon 20mm, a 55 Micro Nikkor lens and the much adored (but probably over romanticized) 105mm 2.5 ais lens and having a wild system that spanned the ages. And probably at the lowest cost of the three system choices.
The sensor in the A7 most probably shares its DNA with the sensor in the Nikon D610 and both of those sensors are highly rated. The 24 megapixel sensors have AA filters in front of them so I suspect that the performance of both is much like the overall performance of the Sony a99 camera with each company changing the secret sauce of file processing to hit the tastes of their respective markets. I'm sure each sensor resolves plenty of detail and does so even at high ISOs. But I think the reason most cognoscenti are looking at full frame isn't necessarily for performance as much as it is the look of the lenses at particular angles of view. The selling point of any larger sensor camera (at least to me) is