see also:

• a catalogue of Micro Four Thirds lenses
• 3x telephoto zoom lenses for Micro Four Thirds

• version I introduced late 2012, this is a premium level lens offering field of view of a 70-200mm lens on a full frame camera but the same depth of field (DOF) as an f/5.6 lens on a full frame camera - so this lens will NOT be replacing the wedding and fashion photographer's main go to full frame lens - the 70-200mm f/2.8.
• constant f/2.8 aperture and silent AF with stepless aperture (HD designation) makes it great for movies as well as still photography
• the f/2.8 aperture is a substantial improvement over the usual kit zoom lenses (usually these are f/3.5-5.6) when it comes to lower light photography or shallower depth of field (DOF)
• it is MUCH smaller, lighter, less expensive and will AF much faster on Micro Four Thirds cameras than the superb Olympus ZD 35-100mm f/2.0 lens, but that Olympus lens allows 1 stop more light, 1 stop shallower depth of field (DOF) and is better optically throughout its range.
• it is a great short telephoto zoom lens for alpine hikers who need a light, weatherproof lens above the tree line that is just wide enough to give a great perspective of the mountain ridges while allowing some reasonable tighter telephoto imagery
• version ii announced in Jan 2017 offers better weathersealing, and smoother aperture variance when zooming
• both lenses can support Dual Sync IS (version I needs firmware upgrade)
• potential buyers should also consider the superb but much heavier and bigger Olympus mZD 40-150mm f/2.8 pro lens and for a telephoto prime lens, the Olympus m.ZD 75mm f/1.8 lens which is better optically and allows more than 1 stop more light and shallower depth of field (DOF), plus it has nicer bokeh

• 70-200mm in 35mm terms
• Power OIS image stabiliser
• dust and splashproof
• Nano coatings for improved flare control
• 'HD' movie capability designation, including linear stepper motor for fast AF
• 18 elements in 13 groups including 1 UED and 2 ED elements
• 7 rounded blades
• close focus 0.85m giving ~0.1x magnification
• internal focus and internal zoom so lens does not get longer
• 58mm filter thread
• 360g
• 67.4mm diam x 99.9mm length
• price $1200-1500

• dpreview.com's brief preview
• ePhotozine's review
  • excellent to outstanding sharpness wide open, especially at 35mm end. Sharpness at 100mm is best at f/4, while at 35mm and 70mm is best at f/5.6.
  • well controlled flare and CA, and some vignetting at f/2.8-4.
• dslr magazine compares image quality of the 35-100mm Panasonic with a Canon 70-200mm f/2.8L IS II lens
  • the Canon tended to have marginally more sharpness/detail but this was on a 24mp full frame sensor compared to 16mp MFT sensor
  • the Panasonic had much less vignetting and distortion, can focus closer and more accurately, weighs only 360g instead of 1,470g, and is just under half the price
  • the review did not compare shallow depth of field (DOF) capabilities, where the Canon would win easily, nor AF on fast moving subjects, but if you don't need shallow DOF or AF on fast moving subjects, then the Panasonic makes a much more compact, light and affordable solution with minimal loss of image quality.
• LensRental.com's tests
  • “At 35mm the lens is awesomely sharp; every bit as good as the Panasonic 12-35mm f/2.8 X HD weatherproof lens is at 35mm. That means it’s as good as most primes, or at least in prime territory as far as resolution goes. It holds up well right out to the corners.”
  • Resolution wide open at 100mm is only 86% of that at 35mm focal length but “easily better than any other (sic Micro Four Thirds) zoom at 100mm”
  • “stopping down to f/4 sharpens the 100mm end up dramatically” and at f/4 is as sharp as at 35mm f/4.
  • the drop off in sharpness wide open from 35mm to 100mm is comparable to the degree of drop off in center sharpness seen in most full frame 70-200mm f/2.8 lenses by Canon, Sigma, Tamron, etc although the new Canon 70-200mm f/2.8 II and the latest Nikon does not seem to have this drop off.
• Admiring Light's review
• LensTip review
  • “We praised the 12-35 mm model so it would be difficult not to praise the 35-100 mm one, especially that it fares a tad better. It works nicer against bright light, its vignetting, coma, astigmatism, chromatic and spherical aberration levels are lower. It loses to its smaller brother only when it comes to the sharpness on the edge of the frame. The high distortion level is also something strange – with such a range of angles of view it shouldn’t have been so pronounced.”
• PhotoReview.com.au review
  • sharpest across the frame at f/5
  • Panasonic cameras with corrected lateral chromatic aberration was negligible across all focal length and aperture settings, Olympus cameras with uncorrected lat CA showed slight fringing esp. at 35mm focal length
• DxOMark's test
  • as good as the Panasonic 12-35mm f/2.8 X HD weatherproof lens but not quite as sharp as the Sigma 50-150mm f2.8 EX DC APO OS HSM Canon but that dSLR lens is twice as long and is an incredible 4x heavier at 1350g!
• thephoblographer.com review
• Photozone.de review
  • “dead sharp in the image center and pretty good in the border region. Since distortions are auto-corrected, there is nothing to worry about here. You may spot some light falloff in the corners at f/2.8 but it's not overly disturbing and gone from f/4 onward. Lateral CAs are quite low. The quality of the bokeh - a major aspect of a fast lens - is very good. The background blur is beautifully rendered and there's almost no bokeh fringing.”