The Olympus mZD 40-150mm f/2.8 Pro lens for Micro Four Thirds has been on the lens timeline for some time but it has now been formerly announced and on paper looks like it may be the highest image quality lens Olympus has made to date – even beating their superb Four Thirds lenses.

Specs at a glance:

• eq. to 80-300mm in full frame terms
• constant f/2.8 aperture at all focal lengths
• dual linear voice coil motors for fast, silent CDAF focusing

• 72mm filter thread
• 160mm long and lens length does not change on zooming or on focussing
• 880g with tripod adapter (760g without)
• collapsible lens hood
• weather-resistant, freeze-proof
• manual focus clutch mechanism
• L-Fn button
• close focus to 0.7m giving subject area of 8x6cm
• optional dedicated MC-14 1.4x teleconverter (~$399) which makes it 56-210 f/4 (eq. to 112-420mm) and will also be compatible with the 300mm f/4 Pro lens when it comes out
• $US1499

Compared to the Olympus ZD 50-200mm f/2.8-3.5 SWD lens for Four Thirds:

• less telephoto but constant f/2.8 aperture and presumably even better optical quality
• optimised for CDAF thus can do silent C-AF during video and is compatible with face detection and eye detection AF (the Four Thirds will only AF fast on a E-M1 and then not in CDAF mode very well at all)
• same length but does not extend on zooming
• lighter 880g vs 1.07kg
• 72mm filter thread vs 67mm
• close focus to 0.7m instead of 1.2m
• at present, only can add a 1.4x teleconverter, there is no 2x teleconverter available as with Four Thirds

Compared to a Canon 70-200mm f/2.8 IS II L on full frame:

• more telephoto (to 300mm not just 200mm)
• 4x zoom not just 3x zoom
• more depth of field (equates to 80-300mm f/5.6 on full frame while the 70-200mm equates to 112-320mm f/4.5 on an APS-C)
• possibly better optical image quality but lower sensor image quality
• optimised for CDAF (see above), whereas the Canon is not
• much lighter 880g vs 1.57kg
• shorter 160mm vs 197mm
• smaller filter 72mm vs 77mm
• closer focus to 0.7m vs 1.2m
• much more affordable $1499 vs $2299
• much better for long periods of hand held use
• much better for hiking
• at present, only can add a 1.4x teleconverter, there is no 2x teleconverter available as with Canon or Nikon

Compared to a Canon 70-200mm f/4 IS L on full frame:

• more telephoto (to 300mm not just 200mm)
• 4x zoom not just 3x zoom
• more depth of field (equates to 80-300mm f/5.6 on full frame while the 70-200mm equates to 112-320mm f/6.4 on an APS-C)
• possibly better optical image quality
• marginally lower sensor image quality of 1 stop (need to increase full frame ISO by 1 stop for equivalence, leaving only a 1 stop advantage to full frame)
• optimised for CDAF (see above), whereas the Canon is not
• same weight without tripod adapter 760g
• shorter 160mm vs 172mm
• larger filter 72mm vs 67mm
• closer focus to 0.7m vs 1.2m
• similar price $1499 vs $1299
• at present, only can add a 1.4x teleconverter, there is no 2x teleconverter available as with Canon or Nikon

Compared to the Canon 70-300mm f/4.5-5.6 DO IS:

• similar focal length field of view and zoom range
• weatherproof (the Canon is not an L lens and is not weathersealed)
• optimised for CDAF (see above), whereas the Canon is not
• marginally more depth of field at wide end, same at telephoto end
• possibly better optical image quality with less artefacts (DO optical design causes artefacts)
• but SIMILAR sensor image quality as need to increase ISO by 2 stops on the full frame for equivalence
• similar weight 760g (w/o tripod adapter) vs 720g
• longer 160mm vs 100mm but does not get longer on zooming
• larger filter size 72mm vs 58mm
• IS more efficient on Olympus cameras
• closer focus 0.7m vs 1.4m
• similar price $1499 vs $1399

It is going to be a great lens, and will compliment the 12-40mm f/2.8 nicely. It will be awesome for a whole range of uses, but particularly for the hikers who would love this range in a relatively light, compact, weatherproof kit.

Personally I would prefer a weatherproof 200mm f/2.8 prime with a 1.4x teleconverter to get me closer to the planned 300mm f/4 PRO if extra super telephoto is needed – maybe such a 200mm will come one day!