The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Panasonic 9mm F1.7 ASPH and the Carl Zeiss Biogon T2,8/21 ZM for their suitability to various photography scenarios:
Size and Weight Comparison
The size of a lens is a crucial factor to consider when comparing two lenses. Carl Zeiss Biogon T2,8/21 ZM is the longer of the two lenses at 75mm. The Panasonic 9mm F1.7 ASPH with a length of 52mm, is 23mm shorter. On the other hand, the Panasonic 9mm F1.7 ASPH has a larger diameter of 61mm compared to the Carl Zeiss Biogon T2,8/21 ZM's 53mm diameter.
The weight of a lens is equally significant as its external dimensions, particularly if you intend to handhold your camera and lens combination for extended periods. Panasonic 9mm F1.7 ASPH weighs 130g, which means it is 150g (53%) lighter than the Carl Zeiss Biogon T2,8/21 ZM which has a weight of 280g.
Filter Threads
The Panasonic 9mm F1.7 ASPH has a filter size of 55mm whereas the Carl Zeiss Biogon T2,8/21 ZM has a 46mm diameter. Larger filters are generally more expensive than the smaller ones given all the other features are equal.
Below are links to the 55mm filters that we recommend you to consider for the Panasonic 9mm F1.7 ASPH:
And these are the 46mm filters that we recommend for the Carl Zeiss Biogon T2,8/21 ZM:
Lens Mounts
The Panasonic 9mm F1.7 ASPH has the Micro Four Thirds lens mount whereas the Carl Zeiss Biogon T2,8/21 ZM has the Leica M lens mount. Some of the latest released cameras that are compatible with these mounts are OM System OM-3 Astro, OM System OM-5 II and OM System OM-3 for the Micro Four Thirds Mount and Leica M EV1, Leica M11-D and Pixii Max for the Leica M Mount.
Focal Range
Panasonic 9mm F1.7 ASPH is a prime lens with fixed focal lenght of 9mm which has an effective (full-frame 35mm equivalent) focal range of
18mm when used on a FourThirds format camera.
On the other hand, the Carl Zeiss Biogon T2,8/21 ZM is a prime lens with fixed focal lenght of 21mm.
