The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Panasonic 100-400mm F4.0-6.3 and the Panasonic 35-100mm F2.8 OIS 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. Panasonic 100-400mm F4.0-6.3 is the longer of the two lenses at 172mm. The Panasonic 35-100mm F2.8 OIS with a length of 100mm, is 72mm shorter. Besides being longer, the Panasonic 100-400mm F4.0-6.3 also has a larger diameter of 83mm compared to the Panasonic 35-100mm F2.8 OIS's 67mm 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. Panasonic 35-100mm F2.8 OIS weighs 360g, 63% (625g) lighter than the Panasonic 100-400mm F4.0-6.3's weight of 985g.
Below you can find the dimension and weight table of the Telephoto Zoom Lenses in Micro Four Thirds Mount for size comparison purposes.
Telephoto Zoom Lenses in Micro Four Thirds Mount for Size Comparison
Lens Mounts
Both the Panasonic 100-400mm F4.0-6.3 and the Panasonic 35-100mm F2.8 OIS 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-5, Panasonic GH6 and OM System OM-1.
Focal Range
Panasonic 100-400mm F4.0-6.3 has a focal range of 100-400mm and 4.0X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of 200-800mm when used on a FourThirds format camera. Panasonic 35-100mm F2.8 OIS has a focal range of 35-100mm and 2.9X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of 70-200mm when used on a FourThirds format camera.