May I interest you in this clip: (21:30 onwards)
YouTube Link: https://www.youtube.com/watch?v=DtDotqLx6nA
It seems like f2.8 aperture throughout the zoom range is PHYSICALLY impossible since aperture is calculated with the formula:
focal length/barrel (or front element?) diameter
focal length changes, but the diameter doesn't. How can aperture stay constant? The Pana 35-100 f2.8 is essentially (in 35mm format) 70-200mm f5.6. Don't know how true it is with this Oly lens..
Interesting video, if you're truly interested, take a watch and let me/us know what you think?
For me, instead of comparing it with the 35mm format, I just play with the lens physically, or at least look at picture samples first. If I like what I see, who cares if the equivalent format is so and so..?