12-60mm F3.5-5.6 Power OIS Panasonic lens

Vitaliy_Kiselev

This zoom offers a versatile focal range of 24-120mm in a relatively small package, backed-up by very good image quality throughout the focal range and impressively fast and quiet autofocusing.
It is a little soft wide-open, so you can try to stop it down for the best results,

http://www.photographyblog.com/reviews/panasonic_lumix_g_vario_12_60mm_f3_5_5_6_asph_power_ois_review/

Vitaliy_Kiselev

http://dc.watch.impress.co.jp/docs/review/lens_review_2/1009732.html

Vitaliy_Kiselev

Sharpness at 12mm is already very good wide open, on tele end lens becomes softer, but not very much. Corners although are quite soft. Distortion and chromatic aberrations are very small.

AF is fast and silent. Lens is fully compatible with Dual I.S.

http://www.mirrorlessons.com/2016/07/20/panasonic-lumix-12-60mm-f3-5-5-6-review/

IronFilm

I use a 24-120 F4 Nikkor on both a D600 (for stills) and paired with a 0.71x speedbooster on a GH4 making it an effective: 17-85mm F2.8 Big yes, but for a constant aperture zoom and a fast-ish f2.8 I'll take it! I use the mounting foot on the SB to help balance & stabilize the weight/mass. It's smaller than the Tamron 28-105 constant f2.8 (Nikon mount) I used to use, lol.

Is a pity there are no active F to MFT adapters so that the IS of the 24-120 could be taken advantage of.