The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Samyang AF 135mm F1.8 FE and the Sony FE 400mm F2.8 GM OSS for their suitability to various photography scenarios:
Size and Weight Comparison
The size of a lens is an important deciding factor when comparing two lenses. Sony FE 400mm F2.8 GM OSS is the longer of the two lenses at 359mm. The Samyang AF 135mm F1.8 FE with a length of 130mm, is 229mm shorter. Besides being longer, the Sony FE 400mm F2.8 GM OSS also has a larger diameter of 158mm compared to the Samyang AF 135mm F1.8 FE's 93mm diameter.
The weight of a lens is as important as its external dimensions, especially if you are planning to hand hold your camera and lens combination for longer periods. Samyang AF 135mm F1.8 FE weighs 772g, which means it is 2123g (73%) lighter than the Sony FE 400mm F2.8 GM OSS which has a weight of 2895g.
Below you can find the dimension and weight table of the Telephoto Prime Lenses in Sony E Mount for size comparison purposes.
Telephoto Prime Lenses in Sony E Mount for Size Comparison
Lens Mounts
Both the Samyang AF 135mm F1.8 FE and the Sony FE 400mm F2.8 GM OSS has the same Sony E lens mount. Some of the latest released cameras that are compatible with the Sony E lenses are Sony ZV-E1, Sony A7R V and Sony FX30.
Focal Range
Samyang AF 135mm F1.8 FE is a prime lens with fixed focal lenght of 135mm. When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of 202.5mm.
Sony FE 400mm F2.8 GM OSS is a prime lens with fixed focal lenght of 400mm. When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of 600mm.