The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Carl Zeiss Distagon T2,8/25 and the Carl Zeiss Distagon T2,8/21 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. Carl Zeiss Distagon T2,8/21 is the longer of the two lenses at 109mm. The Carl Zeiss Distagon T2,8/25 with a length of 90mm, is 19mm shorter. Besides being longer, the Carl Zeiss Distagon T2,8/21 also has a larger diameter of 87mm compared to the Carl Zeiss Distagon T2,8/25's 64mm 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. Carl Zeiss Distagon T2,8/25 weighs 480g, which means it is 120g (19%) lighter than the Carl Zeiss Distagon T2,8/21 which has a weight of 600g.
Below you can find the dimension and weight table of the Wideangle Prime Lenses in Pentax KAF Mount for size comparison purposes.
Wideangle Prime Lenses in Pentax KAF Mount for Size Comparison
Lens Mounts
Both the Carl Zeiss Distagon T2,8/25 and the Carl Zeiss Distagon T2,8/21 has the same Pentax KAF lens mount. Some of the latest released cameras that are compatible with the Pentax KAF lenses are Pentax KF, Pentax K-3 III and Pentax K-1 II.
Carl Zeiss Distagon T2,8/25 is also available in Nikon F (FX) mount.
Carl Zeiss Distagon T2,8/21 is also available in Canon EF and Nikon F (FX) mounts.
Focal Range
Carl Zeiss Distagon T2,8/25 is a prime lens with fixed focal lenght of 25mm. When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of 37.5mm.
Carl Zeiss Distagon T2,8/21 is a prime lens with fixed focal lenght of 21mm. When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of 31.5mm.