Price (RRP): $1,399 (store price)
This is a first. I don’t think we’ve ever reviewed a camera lens before on this site. But when the Nikkor Z 85mm f/1.8 S prime lens was offered, I figured it’d make an ideal opportunity to talk about aperture.
But, first, what product am I talking about? Nikkor is Nikon’s lens brand, and for decades it has been one of high repute. The Nikkor Z 85mm f/1.8 S is a prime lens designed for Nikon’s new Z range of full-frame mirrorless cameras. We reviewed the higher end Nikon Z7 here. Nikon provided the slightly more affordable Z6 with the lens for the purpose of this review.
So, if you’re new to interchangeable lens camera photography, you might be asking, “What is a prime lens?” Well, it’s a lens with a fixed focal length. It does not zoom. It will give you just one angle of view.
And that is, of course, limiting. A modern zoom lens is thing of wonder. Depending on the model, you can use a zoom to “virtually” take you up to a building’s window, then zoom out and photograph the whole structure. With a prime lens you need to move yourself or your subject to photograph different aspects of it.
So why go prime? Well, a zoom lens involves compromises. Its several glass elements have to be able to manage the demands of keeping all wavelengths of light aligned over a range of focal lengths. It should be no surprise that the more expensive, higher quality zoom lenses typically keep themselves down to a zoom range of around 3x, while the super zooms are cheaper … and lower quality.
How fast can the Nikkor Z 85mm f/1.8 S lens go?
Another thing traded off by zoom lenses is what is often called “speed” or “brightness”. They are jargon for the amount of light that a lens can capture and pass through to the sensor. A “fast” lens lets in more light and the more light, the faster the permissible shutter speed. One measure of the “speed” or “brightness” of a lens is its maximum aperture – how wide it can open its iris.
It’s an impressive zoom lens on a full frame camera with a maximum aperture of f/2.8. The maximum aperture of the Nikkor Z 85mm f/1.8 S lens is in the name. That’s a wide aperture, and its especially wide for a moderate telephoto lens. This is a fast lens, as I was to later discover.
How fast? An f/1.8 lens lets in roughly 2.4 times the amount of light that’s transmitted by an f/2.8 lens.
A fast lens can operate effectively at lower light levels than a slower lens. These days, that means you can hand-hold later at night thanks to a faster shutter speed, or without having the camera force the ISO to as high a level (which usually results in more noise).
Remember, though, f/1.8 is the maximum aperture – the widest that the iris will open. Unlike the cameras in most phones, the aperture can be narrowed, in the case of this lens, down to f/16.
The other thing delivered by an f/1.8 aperture on a full frame camera is the potential for a very shallow depth of field. Smart phone makers try to fake this in their camera apps. But this lens provides the real thing: a smooth, appropriate-depth bokeh, thanks to the curved nine-blade iris.
The focal length of the Nikkor Z 85mm f/1.8 S lens is also in the name. 85mm is a moderate telephoto. Back in the olden days of 35mm film photography, a 50mm lens was regarded as the midway point between wide angle and telephoto lenses. Kind of neutral. A focal length of around 70mm was generally thought ideal for portraits. A longer lens tends to avoid the distortions of wide-angle lenses, which might emphasise nearer details such as the nose. I think that these days, living as we do in a world of selfies, we’re somewhat immune to that kind of distortion. Nevertheless, a careful photographer tries to avoid those kinds of things.
But 85mm is only moderately telephoto. Real telephoto in a full frame camera really starts around 100mm and can go up to a metre or more.
So, is it limiting? Well, yes, of course. I was standing on a beach and would have liked to capture the long sweep of sand along with the headland and ocean crashing against it. The field of view was not wide enough to do that. I had to pick and choose amongst subjects, or try to walk several hundred metres to secure a new angle or greater distance. I went to a zoo and the lions decided to remain right in the middle of their enclosures, making close, detailed shots impossible.
But much of the time, a lens like this just forces one to be a bit more inventive or to move around more.