Review: Sony Alpha 7R II interchangeable lens camera
4.5Overall Score

Price (RRP): $4499 (body only)
Manufacturer: Sony

Well, this camera is really called the Sony α7R II, but just in case the α (“alpha” symbol) doesn’t render well with some browsers, we’ll stick with Sony Alpha 7R II. This is a fascinating camera, combining high end features into a form rarely seen.

Features

In summary, I’d call the Sony Alpha 7R II a compact form, mirrorless, full frame, interchangeable lens, digital camera. Some of those characteristics are unusual when combined with the others. In particular: “full frame” doesn’t normally go with “compact”.

Full frame means that the sensor, the electronic film if you like, is the same size as the frame of film used in an old 35mm single lens reflex film camera. That makes it 35.9mm wide by 24mm tall. A big frame means a lot of real estate to populate with pixels. Sony has plastered an effective 42.4 million pixels on this one. For those who’d prefer to think linearly, that makes for maximum size shots of 7952 by 5304 pixels.

Back-illumination

Sony uses CMOS sensors, branded “Exmor” and in this camera it uses what it says is “the world’s first 35mm full-frame CMOS image sensor with back-illuminated structure”.

Back illuminated? Sounds like they’ve put a little LED back there behind the sensor to glow on it. Which of course makes no sense.

In fact, “back illuminated” in this context means that the active element of the sensor has been flipped front to back, so that the “photocathode” layer is at the front, just behind the colour filters. So the “back” of the sensor is “illuminated” by the light from the lens because it is now at the front. That allows the wiring that connects all those pixels, plus the other silicon that supports the operation of the sensor, to be behind the sensitive layer with respect to the lens, instead of in front of it. Most of the light could still get through all that stuff, particularly when the pixels were large (as they tended to be in full frame digital cameras). But more can get through with the new arrangement.

The kind of figures bandied around – not necessarily by Sony – are an increase from 60% to 90% effective.

Um, why? Or, rather, why now and not fifteen years ago?

Because pixel size mattered for the efficiency of light transmission, it wasn’t a problem with the large pixels on full frame cameras. But when you pack over forty million of them in there, the pixels are starting to get quite small, so the back illumination becomes more important.

The net result: higher sensitivity in low light situations, which means less need for artificial ISO boosting and lower noise.

Compact

One of the startling things about this camera is how very close the sensor is to the E-mount for the lens. Of course, being mirrorless there’s nothing standing in the way so some care is required. I’d guess that the body of the camera is about as small and light as can be managed with a full size sensor. The body is 127 mm wide, 96mm tall and a hair over 60 mm deep. With battery, it weighs
625 grams. It is solidly built with a magnesium alloy frame.

But how big and heavy it will be in practice depends on the lens you use. Sony provided an interesting f/4 24 to 70mm Carl Zeiss Vario-Tessar zoom lens to help with the review. Just as well, since I don’t happen to have a collection of E-mount lenses to hand. With this camera a 24 to 70mm zoom is equivalent to, in 35mm film camera terms, a 24 to 70mm zoom. No mental conversions required when you’re using a full frame camera. That’s just a bit short of a 3x zoom (2.92x to be more precise). This lens costs $1599, so all together the cost of the camera as tested was $6098.