The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Samyang 21mm F1.4 ED AS UMC CS and the Olympus M 17mm f2.8 Pancake 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. Samyang 21mm F1.4 ED AS UMC CS is the longer of the two lenses at 68mm. The Olympus M 17mm f2.8 Pancake with a length of 22mm, is 46mm shorter. Besides being longer, the Samyang 21mm F1.4 ED AS UMC CS also has a larger diameter of 64mm compared to the Olympus M 17mm f2.8 Pancake's 57mm 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. Olympus M 17mm f2.8 Pancake weighs 71g, 74% (204g) lighter than the Samyang 21mm F1.4 ED AS UMC CS's weight of 275g.
Below you can find the dimension and weight table of the Wideangle Prime Lenses in Micro Four Thirds Mount for size comparison purposes.
Wideangle Lenses in Micro Four Thirds Mount for Size Comparison
Filter Threads
The Samyang 21mm F1.4 ED AS UMC CS has a filter size of 58mm whereas the Olympus M 17mm f2.8 Pancake has a 37mm diameter. Larger filters are generally more expensive than the smaller ones given all the other features are equal.
Below are links to the 58mm filters that we recommend you to consider for the Samyang 21mm F1.4 ED AS UMC CS:
And these are the 37mm filters that we recommend for the Olympus M 17mm f2.8 Pancake:
Lens Mounts
Both the Samyang 21mm F1.4 ED AS UMC CS and the Olympus M 17mm f2.8 Pancake has the same Micro Four Thirds lens mount. Some of the latest released cameras that are compatible with the Micro Four Thirds lenses are OM System OM-1 II, Panasonic G9 II and OM System OM-5.
Samyang 21mm F1.4 ED AS UMC CS is also available in Canon EF-M , Fujifilm X and Sony E mounts.
Focal Range
Samyang 21mm F1.4 ED AS UMC CS is a prime lens with fixed focal lenght of 21mm which has an effective (full-frame 35mm equivalent) focal range of
42mm when used on a APS-C / DX format camera.
On the other hand, the Olympus M 17mm f2.8 Pancake is a prime lens with fixed focal lenght of 17mm which has an effective (full-frame 35mm equivalent) focal range of 34mm when used on a FourThirds format camera.