The 75-300mm was announced with the original PEN (E-P1), and while we haven't yet tested it, it definitely makes an interesting alternative if you're looking for a telephoto option for your micro-four-thirds body. Since Olympus digital SLR cameras employ the four-thirds imaging sensor, any lens attached to the body will have an effective focal length (in 35mm terms) of double the listed length. Thus, for this particular lens, it will exhibit an effective focal length of 80-300mm. The lens takes 58mm filters, and comes with a cone-style lens hood. Number 2 people soon realize that the lens is not small, and/or realize that f/2.8 on µ4/3 is not the same as f/2.8 on FF. They either sell the lens because it's too big to carry around, or then they go and buy a hi-spec Sony FF. If there's a price to be paid for the excellent sharpness results we've just seen, it might be in below-average performance in handling chromatic aberration. The lens appears to be optimized for use in the telephoto spectrum (>70mm): from 40mm to 70mm, chromatic aberration is evident at all apertures. Further than 70mm however, chromatic aberration becomes less of an issue (the lens grouping focusing on the more central portions of the glass).

While you're not going to get pro lens levels of detail, the 40-150mm R delivers good sharpness across almost the entire zoom range. As you'd expect, things get a bit soft at the long and wide ends, with peak performance reached in the mid-range –though there's some weakness in the corners throughout. Having said that, the results are usable, and the objective measurement comes from testing using instruments that measure MTF**. Lenses will have usually three numbers associated with each f stop, one for the center where sharpness is usually best, one for the edges (lower), and one for the corners or extremes(worst). With zoom lens you get even more variations, and with the Olympus 40-150 f2.8 it's sharpest images come at about 100mm at f4. The MTF there is a whopping 3,124. Whether this is a sensible trade-off depends on your photography. If you shoot moving subjects in poor light, the twice-as-bright F2.8 will give you more light at faster shutter speeds, ideal for avoiding motion blur and noisy high ISOs. And because it passes more light, autofocus tends to work better. Olympus Micro Four Thirds compatible cameras automatically correct distortion in camera, so the following won't be noticeable if shooting JPEG images, or if the software supplied with the camera is used to convert the RAW images. For a lens with a zoom range over three times, distortion is very well controlled at both ends of the zoom range. Imatest detected 2.8% barrel at 40mm and 0.5% pincushion distortion at 150mm, which are both very mild levels. The distortion pattern is uniform across the frame, so correcting this in image editing software afterwards should be a straightforward affair. In-camera corrections remove distortion from JPGs, and Adobe Lightroom already has a profile to correct Raw shots. If you use a different processor, you might see some pincushion distortion when you zoom in, but that's pretty easy to remove.Summing this section up, the OM System 40-150mm F4 PRO lens is easy to use, easy to carry and delivers good performance across the board. OM System 40-150mm F4 PRO M.Zuiko Hands-on Review Summary This compact telephoto zoom is an excellent addition to the OM System Olympus PEN-F + Olympus M.Zuiko 40-150mm f/4.0-5.6 R (45mm, 1/125 sec, f/4.1, ISO200) (Image credit: James Artaius) Olympus M.Zuiko 40-150mm f/4.0-5.6 R: Key features

With my Lumix GX80 camera I compared it with the Lumix 45-150 OIS lens and had a slight preference for the optics of this one, which also - believe it or not - focused more consistently and with less hesitation than the Lumix, which was, however, smoother to operate. This lens isn't a ''constant'' lens, in that as you increase the focal length, the widest aperture is restricted (showing a higher f-number). The following table reflects the changes: Focal Olympus E-M1 Mark III with OM System 40-150mm F4 PRO M.Zuiko lens at 150mm (300mm equiv.), F4, 1/1600s, ISO 200. Every so often we’ll encounter an optic which makes us gasp. We all have our favourite lenses and that will vary depending on our system and the things we shoot. Each lens will have its own character and that’s usually demonstrated by its handling of contrast, colour, the quality of out of focus areas, and of course sharpness. In fact sharpness is the one attribute which gets flogged to death in lens discussions and I will say that as a portrait photographer sharpness is not always top of my list. But in nature and sport photography sharpness is crucial – in this line of work we do need to show as much detail as possible in our subject and kit lenses won’t always cut the mustard. The tests carried out with this lens were all done at f2.8, which is like shooting a full frame camera at about f5.6 (if you shoot APS-C then the difference in depth of field between Micro 4/3 is quite minimal in practice). As you can see, my depth of field was extremely shallow, and I have to be very precise with my focus point on my subjects’ eyes.There's some light distortion evident in photographs taken with the 40-150mm; some barrel (bloated) distortion less than 70mm, and pincushion (squeezed) distortion between 70mm and 150mm. There is a nice point of parity just shy of 70mm where there is essentially zero distortion. Finally at 150mm, sharpness levels drop a little across the frame at maximum aperture, but remain very good in the centre whilst approaching good levels towards the edges. There is little difference in edges sharpness with the lens stopped down, although sharpness in the centre does reach excellent levels at f/8 at this focal length. I bought this lens used, and for what it is, it is a good lens. It is relatively cheap, in comparison to other manufacturer's kit telephoto zoom, as the e-520 has its own stabilization in the body. It is also very small and lightweight, and fits my small bag. A great piece of telephoto zoom for what it is worth. Olympus E-M1 Mark III with OM System 40-150mm F4 PRO M.Zuiko lens at 75mm (150mm equiv.), F5.6, 1/100s, ISO 200.