Understanding Sony lens names and acronyms

It’s Less Complicated Than You Think

“What’s in a name?” Shakespeare’s Juliet once asked.

Plenty, especially if it’s the name of a lens.

But once you start breaking it down you’ll see there’s a common base structure and a few key acronyms or abbreviations that indicate the lens series or special features.

And once this becomes familiar, you’ll realize you’ve learned a lot about photography basics.

As an example, let’s use Sony’s FE 100mm F2.8 STF GM OSS lens*.

* Winner of EISA’s 2017-2018 compact camera system lens award and known for its exceptional bokeh (out-of-focus area blur).

Lens Name Elements and Explanations

Element Meaning Explanation
FE Full Frame E Mount

There’s a lot to unpack in this two-letter acronym, but we’ll start with a quick explanation about sensors.

If you have a DSLR or mirrorless camera with interchangeable lenses, you can see a shiny, rectangular sensor inside the camera body when the lens is not attached. In digital cameras, this sensor performs a similar role to film in analog cameras – it captures the light coming in through the lens and records it as an image.

Cameras can have different sensor sizes. The bigger the sensor, the more light – and therefore, more image detail – it can record. Larger sensors also provide a wider angle of view, able to capture more of the scene in front of you. Digital cameras with sensor sizes that perform about the same as standard 35mm film cameras are called full-frame cameras. Cameras with smaller sensors are called crop-frame cameras.

The “F” in FE means the lens was specifically designed for the larger sensor of a full-frame camera. You can easily imagine that if the sensor is bigger, the lens also needs to be bigger to cast an image over the entire sensor. Lenses optimized for crop-frame cameras don’t have this “F” in their names. An example is Sony’s E 50mm F1.8 OSS.

Now for the “E” in FE. A camera and lens will each have a mount so they can connect and talk to each other. Mounts are typically named with a unique letter and Sony has just two types – A and E. An E-mount camera will be natively compatible with an E-mount lens. There are adapters that connect different types of mounts together, but most come with some downsides.

Note: If you have a full-frame Sony camera, like the a7r II or a9, you might think you can only ever use full-frame lenses, but this isn’t true. And full-frame lenses will actually work well when mounted on crop-frame cameras, though the effective focal length will change.

100mm Prime lens with fixed focal length of 100mm

Focal length determines the angle of view and magnification. A lens with a focal length of 24mm will give a wide angle of view (great for capturing sweeping vistas) but will have low magnification. A 200mm lens will have a narrow angle of view but high magnification (great for capturing detail on objects that are far away).

If you can adjust the focal length of a lens it’s called a zoom lens, if you cannot, it’s called a fixed (or prime) lens. Prime lenses usually provide better quality and performance because they only need to be optimized for one focal length.

There’s just one focal length noted for the FE 100mm F2.8 STF GM OSS, so it’s a prime lens. Zoom lenses would have a range, for example: 24-70mm. A lens with a focal length of more than 100mm is considered to be a telephoto lens, capable of magnifying and shooting objects at a longer distance.

F2.8 Maximum aperture of F2.8

The size of the aperture determines how much light enters the lens and reaches the sensor. And the more light the lens is able to pass through, the better it will perform when there isn’t a lot of light available. Lenses that have large maximum apertures (that is, they can open very wide) are called “fast” lenses because of this.

The unit that measures the aperture size is called an “f-stop,” and somewhat counterintuitively, the larger the aperture, the smaller the f-stop. A max aperture of F2.8 (also written as f/2.8) means that when open wide, the lens aperture is fairly large. So this lens is a fast lens.

Note: Along with sensor size, aperture also controls another very important aspect of photography – depth of field.

STF Smooth Transition Focus

The FE 100mm F2.8 is Sony’s first STF lens. STF is Sony’s way of saying there is special technology in the lens to create a soft and smooth transition for bokeh (out-of-focus area blur), resulting in a more natural look. The more common term for this technology is apodization. So instead of STF, Voigtlander will add “APO” to its lens names; Fuji will add “APD.”

GM G Master brand (lens series)

G Master is Sony’s flagship brand, intended for its professional-grade interchangeable lenses. These lenses are optimized for high resolution and perfect bokeh when mounted on full-frame E-mount cameras.
» Learn more about Sony’s different lens brands

OSS Optical SteadyShot

Optical Steadyshot (OSS) means the lens has image stabilization. Image stabilization technology can be found in either the lens or the camera body. It counteracts unwanted camera movement or shake, which in turn can cause unwanted effects in the resulting photo.

Note: OSS is only useful if your camera body doesn’t have image stabilization, as they would interfere with each other and are never used at the same time anyway. Recent Sony cameras come with sophisticated 5-axis image stabilization.

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