Micro Four Thirds users have a lot of consumer-grade choices when it comes to telephoto lenses. Unfortunately, the same can’t be said of any serious lenses – fast aperture, fast focusing, or even prime. Thanks to the 2x crop factor, this is one of the places where M43 actually offers a substantial advantage over larger formats. It’s just a shame that there aren’t any telephoto lenses of serious optical quality to make the most of this. Wildlife photographers and sports shooters still favor DX crop bodies when there’s enough light – the increased pixel density and extra 1.5x reach can’t be ignored. I was still birding during Nikon’s transition to FX with the D3; I remember being frustrated at the quality of the sensor, but the lack of reach. There are some species that simply will not allow you to approach close – I frequently used a 500mm with 1.4x TC on a DX body, for a total of 1,050mm f5.6 equivalent. To reach 1,000mm on FX, you’d be a stop down in brightness and having to deal with the associated optical quality limitations of a 2x teleconverter.

Collapsed at 100mm.

Fully extended. This is not a short or discrete lens, and I haven’t even added the hood yet.

The current crop of M4/3 lenses stops at 300mm. This gets you to 600mm equivalent; the Olympus 75-300/4.8-6.7 (150-600mm equivalent) and Panasonic 100-300/4-5.6 (200-600mm equivalent) are your only two options. (A 300/4 or 400/5.6 with Olympus’ MSC-grade fast AF would be wonderful, but sadly not to be – at least not yet). The Olympus is the more compact of the two (and by all reports, slightly sharper too), but also quite a bit more expensive than the Panasonic – US$899 vs US$599-699 or so. The bigger issue is that you’re down half a stop on the Panasonic; with complex multi-element zooms, this difference in physical aperture translates into more when it comes to light transmission. The Panasonic is probably closer to T7-T8; the Olympus may well be at T9-11. More worrying is that with both lenses you’re going to be right up against the diffractions limits of the higher density M4/3 sensors, such as the OM-D and GX1, even when shooting wide open. To be useable at 300mm, this lens has to perform optically – we’ll address this later.

Untitled. OM-D, 100-300

The 100-300 is a moderately-sized lens, weighing in at about 500g and similar in heft to consumer DSLR 70-300 lenses. Despite only having to cover the M4/3 image circle, it isn’t any smaller; size advantages are more apparent in wideangle lenses due to the short back focus distance of mirrorless cameras not requiring a rear telephoto group*. The lens has a 67mm front thread, metal rear mount and front plastic bayonet hood; this is included with the lens. (Olympus, I’m looking at you: not including lens hoods is just penny pinching.) The zoom ring is a broad, rubber affair that should be easy to operate, but is actually very difficult to set precisely in practice because of friction between the plastic surfaces inside the lens; it tends to bind and move in jumps. There is an ample focus ring up front, narrower than the zoom ring and distinguishable by touch, but it runs fly-by-wire and obviously has no hard stops at either end of the range. With telephoto lenses, it’s nice to have the ability to place the focus range by feel, or at least kick it over in either direction closer to the subject distance to avoid hunting – especially important with the CDAF systems used in mirrorless cameras. Overall, build quality is acceptable at this price point, but nothing to write home about. The plastics feel a little brittle and thin, I’m generally fairly careful when handling this lens.

Caught in the act. OM-D, 100-300

*The rear telephoto group on a lens is used to straighten out the image-forming rays so they fall perpendicular to the sensor, and extend the image plane further than the natural distance associated with the focal length – in order to clear SLR mirrors. This distance is proportional to the focal length of the lens. Rangefinders and mirrorless cameras can use symmetric retrofocal lenses whose rear elements can be positioned very close to the sensor, making the lenses physically much smaller. Lenses with a focal length longer than the flange distance do not require the rear telephoto group to project the image plane out to clear the mirror, which is what removes the size advantage between DSLRs and mirrorless cameras for lenses over 50mm or so.

Reminds me of Gibraltar for some reason. OM-D, 100-300

However, by far the biggest gotcha of the whole setup is that the lens is physically large and not well balanced at all, especially on the smaller M4/3 bodies; even the OM-D requires a grip for optimal handling. Given this, the omission of a tripod collar is unforgiveable; you simply can’t mount it on the body’s tripod socket because it not only places a large amount of stress on the mount, but it’s also impossible to frame precisely especially at 300mm, because the image frame droops perceptibly through the viewfinder. This means you’ve got to shoot it handheld; here, the relatively light weight of the whole system works against you, because there isn’t enough mass to damp the vibration. And forget about using it at arms’ length without an EVF. The good news though is that the OM-D’s EVF and IBIS system are excellent, and allow you to brace the entire setup against your forehead. Being a Panasonic optic, the lens has moving-element OIS built in; and it’s pretty effective, too. Although it’s very difficult to scientifically test, I feel that perhaps the IBIS in the OM-D is very slightly more effective than OIS built into the lens – but it could go either way, really. Both systems allow consistent critically-sharp-at-100% handheld shots at 1/100s and 300mm, which is about 2.5 stops. You could probably push it a stop further, but then your hit rate will fall considerably.

Painterly. OM-D, 100-300

Let’s talk a bit about optical performance. The lens is a 17/12 design with one ED lens and several aspherical elements; no fancy coatings, but a decent specification that should yield decent optical results. Like most of these consumer telephoto designs, performance is surprisingly good below 200mm; 200-300mm is so-so, with weakest performance at 300mm. Stopping down by one stop below 200mm improves clarity a hair, but anything more starts to reduce resolving power due to diffraction. At 300mm, f8 is slightly better than f5.6 because there’s less chromatic aberration and improved contrast, however, the resolution gains are once again offset by diffraction losses. There isn’t any point in going beyond f11, even though the minimum possible aperture is f22.

Surprisingly decent bokeh. OM-D, 100-300

The lens never gives you the impression of clarity or transparency as the best lenses do; there’s always a layer of something between you and the image, which can be somewhat ameliorated through good postprocesing. No amount of postprocessing can put back the missing microcontrast, however. Part of the problem is there’s chromatic aberration visible at all focal lengths; this causes the image to separate out slightly, reducing resolving power. It’s especially obvious in the corners and at high contrast edges at the 300mm end of the zoom range; a good 2-3 pixels’ worth at times. There is some vignetting, but it’s very, very minor and easily correctable. Finally, bokeh is surprisingly smooth, though large out-of-focus highlights have the telltale texture that signifies the use of moulded hybrid glass-plastic aspherical elements.

Lily pads. OM-D, 100-300

All of this said, the 100-300 is still a cut above most of the consumer-grade offerings; I haven’t used the Olympus 75-300, though. I certainly don’t think the Nikon 70-300VR had this level of resolution – on the lower pixel density D700 and D7000 bodies, the 70-300VR’s resolution above 200mm left much to be desired.

Contemplation. OM-D, 100-300

So what’s the 100-300 useful for? To be honest, I bought it out of curiosity and the lack of a telephoto solution for any of my other systems. It’s actually a pretty good option for reach in a pinch, especially when you’re not sure you’re going to need it – and don’t want to carry around a large 300, 400 or 500mm supertelephoto. The combination of lens and OM-D doesn’t occupy much space in the bag at all. Aside from slightly reduced optical quality and a slower aperture, the biggest limitation is continuous AF performance. It’s already a problem for the M4/3 system since all focus systems are contrast detect; it’s even worse with the 100-300 because the focus motor itself is slow, the required amount of physical movement of the lens elements between the infinity and the 1.5m near limit is large, and the lens is one of the earlier generation of designs that doesn’t have the benefit of the technology used in Panasonic’s current lenses. It isn’t slow per se, but it definitely isn’t up to the latest Olympus primes in speed. Note that I’ve had a couple of experiences where the camera/lens confirmed focus, but it turned out that things weren’t quite perfect. Very shallow critical depth of field (especially at closer distances) is nothing new with telephotos, but it’s not easy to tell without magnification exactly which small bit of the frame is in critical focus with current EVF/ LCD technology.

Crowded. OM-D, 100-300

Given those limitations, I think its strength is probably in situations where you need reach or perspective but your subject isn’t moving much, if at all; some forms of wildlife, landscapes and perhaps even architecture or abstracts; I tried using it for street work, but it just felt far too conspicuous. It’s also surprisingly difficult to frame a 600mm FOV shot when there are a lot of people about – the foreground takes forever to clear, and by the time it does, your primary subject has probably moved on. That said, I used it without issue at a recent concert I was covering – in that case, it’s all about timing and making sure that your subject hasn’t moved out of the depth of field of the lens, which is actually a bit more than you’d expect. It’s also worth noting that whilst AF is fast and positive up to about 200mm, beyond that if the new subject is far outside the previous subject distance, or contrast is only moderate, you’re going to see situations where the combination hunts and sometimes even fails to find focus.

Smoke break. OM-D, 100-300

I think the best litmus test for any lens is the question of ‘given a chance, would you buy it again?’ I didn’t pay very much for mine on the secondary market – mint, boxed, pretty much as new ran all of $400 – so yes, I definitely would. It’s not a staple lens for me, but it is fun, does offer something that none of my other lenses can, and the optics are good enough. Overall – recommended, but with caveats. MT

The Panasonic 100-300/4-5.6 is available here from B&H and Amazon.

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On the lookout. OM-D, 100-300