It’s the week of fresh lenses! After Tokina, Sigma and Tamron now it’s Sony’s turn: Meet the Sony FE 135mm f/1.8 GM full frame prime lens, which indeed seems to be a fine piece of glass for your E-mount camera of choice!
G Master. This is Sony’s brand name for their top line of lenses: A resolution of at least 50 lines per millimeter and pleasing bokeh without halo effects are just two examples of the high standards Sony requires from their engineering teams in order to build a GM branded lens. The Sony FE 135mm f/1.8 GM prime meets these requirements. Easily.
Sony FE 135mm f/1.8 GM Prime Lens
This new 135mm GM lens offers a really fast aperture in relation to its focal length. Other Sony offerings include the FE 100mm f/1.8 STF GM OSS, which lacks 35mm of focal length or the FE 70-200 f/2.8 GM, which lacks 1.5 stops. Right in the middle: The Sony FE 135mm f/1.8 GM.
This lens features the best Sony has to offer but it comes at a price, of course. literally speaking it is not cheap but it is not exactly lightweight either. Measuring 89.5mm x 127mm (3.52″ x 5″) and weighting 950 g (33.6 oz) this lens is meant to be used as a serious tool. Inside, 13 elements in 10 groups work together to render that perfect picture. Additionally, the aperture consists of 11 blades, resulting in a smooth and pleasing bokeh.Of the total of 13 lens elements, three of them are special: one extreme aspherical lens (XA lens), one super ED glass (extra-low dispersion) and one ED glass (low dispersion). These elements help to reduce chromatic aberration, color fringing and other optical flaws while producing rich contrast and high resolution throughout the frame. Check out the MTF (Modulation Transfer Function) charts above.  is a chart for a wide-open aperture of f/1.8,  is based on an f/8 aperture.
The vertical axis represents the overall contrast (%), the horizontal axis represents the distance from the optical center of the lens (mm).  represents the spatial frequency @ 10 line pairs/mm  and 30 line pairs/mm . The bold lines represent radial values while the dotted lines represent tangential values. The optimum would be a straight horizontal line across the top of the chart (100%) and as you can see the Sony FE 135mm f/1.8 GM is not too far off here.
In order to achieve fast, accurate and silent auto focus, Sony uses not one but two XD (extreme dynamic) linear motors for focussing. The whole lens body is made out of a durable, yet lightweight magnesium alloy and on the outside, the lens features a dust and moisture resistant design.
Focusing Features and De-Clickable Aperture
When focussing manually, the focus responds linearly to the rotation of the focus ring which is nice since fly-by-wire focussing can be a bit fiddly. Not one but two customizable buttons can be found on the outer lens. This comes in handy when shooting in portrait orientation.
One thing that’s really nice for indie filmmakers is the option to de-click the aperture with just a flick of a switch. This lens has been designed with both, still photographers and filmmakers in mind. Neat!
Advanced nano AR coating has been applied to the internal lenses to suppress unwanted internal reflections and ghosting effects. The front element additionally sports a fluorine coating that resists nasty fingerprints and makes it easy to clean.
You can use this lens with any full frame E-mount camera but you also can use it with a APS-C model, of course. In that case the focal length becomes a 35mm equivalent of 202.5mm. In any case the minimum focus distance is set to 0,7m (2.3 ft). The front diameter of this lens is 82mm.
Sony vs. Sigma
The obvious competition for this lens is the Sigma 135mm f/1.8 DG HSM Art for Sony E-mount. When comparing the two on paper, the Sigma is actually a bit heavier (2.49 lbs / 1130 g) and a bit larger (3.60″ x 4.52″ / 91.4mm x 114.9mm) than the Sony FE 135mm.
On the other hand, the Sony is more expensive. Let’s see how these two lenses compare in the real world! I’m really curious how both lenses compare when shooting with something like the Sony a7 III.
Do you own or use Sony glass? What do you think of this new 135mm telephoto lens? Share your thoughts in the comments below!