The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Samyang 20mm F1.8 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 20mm F1.8 is the longer of the two lenses at 88mm. The Olympus M 17mm f2.8 Pancake with a length of 22mm, is 66mm shorter. Besides being longer, the Samyang 20mm F1.8 also has a larger diameter of 83mm 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, 85% (426g) lighter than the Samyang 20mm F1.8's weight of 497g.
Filter Threads
The Samyang 20mm F1.8 has a filter size of 77mm 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 77mm filters that we recommend you to consider for the Samyang 20mm F1.8:
And these are the 37mm filters that we recommend for the Olympus M 17mm f2.8 Pancake:
Lens Mounts
Both the Samyang 20mm F1.8 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 20mm F1.8 is also available in Canon EF , Canon EF-M, Fujifilm X, Nikon F (FX), Pentax KAF, Samsung NX, Sony Alpha and Sony E mounts.
Focal Range
Samyang 20mm F1.8 is a prime lens with fixed focal lenght of 20mm.
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.