출처 http://slrgear.com/reviews/showproduct.php?product=1840

Sharpness 
Given our experience with Olympus' previous Zuiko Pro lenses, we expected great results from this 300mm lens…but we weren't expecting them to be this good. Wide open, the lens is tack sharp across the entire frame. Looking at our blur charts, the blur characteristics are practically completely flat across the frame and extremely sharp corner-to-corner. Exceptional sharpness is maintained as you stop down, though we do see minor diffraction-related softness come into play around most around ƒ/16-ƒ/22, but it's quite minor. All said and done, the Olympus 300mm ƒ/4 Pro is fantastically sharp.

As with the earlier Olympus 40-150mm ƒ/2.8 Pro lens, the new 300mm is compatible with the Olympus MC-1.4x teleconverter. Though you lose a stop, the sharpness of the lens at its new ƒ/5.6 maximum aperture is still impressive. We see about a 1-blur-unit drop in overall sharpness, but images are still very crisp. Sharpness still remains even across the frame as well, and, again, minor diffraction-related softness being observed mostly around ƒ/16-ƒ/22.

개방부터 주변부까지 아주 샤프함.f8까지 샤프니스가 그대로 유지되고 f11에서 회절이 영향을 미침. 

MC14를 끼면 블러 유닛이 한단계 떨어지지만 그래도 샤프한 편임.

Be careful with shutter shock!
For critical sharpness, reducing vibrations is a key element. For DSLRs, one of the main tips is to use mirror lock-up when available to reduce or eliminate the vibration caused by the mirror slap prior to exposure. For a mirrorless camera, which is, well, mirrorless, the shutter is open most of the time. The first curtain must close first before re-opening in order to make the exposure. This can induce subtle, yet noticeable vibrations that result in blurry images.

When testing the Olympus 300mm ƒ/4 Pro, initially using our Panasonic GX1 test camera, we observed noticeable image blurring on some of our VFA test chart images, despite using a massive Cambo studio tripod and long 10-sec self-timer. We then swapped over to an Olympus E-M1 with v4.0 firmware. In this latest software update, in addition to the previously introduced "anti-shock" shooting mode, it also offers a full "silent" mode that uses only an electronic shutter -- thus being completely vibration-free.

We tested all three primary shooting modes with the E-M1 (single-shot, anti-shock and silent modes), and found the Silent mode did indeed provide the sharpest images with the Olympus 300mm. Testing this again handheld with I.S. enabled, we also found similar results, with Silent mode producing better images when using a slower shutter speeds (1/125s for our handheld tests, for example).

Olympus 300mm Shutter Shock Tests (300mm, f/7.1, 1/80s, I.S. Disabled)
300mm f/4 Pro Single-Shot (Normal)	75-300mm  Single-Shot (Normal)
300mm f/4 Pro Anti-Shock Mode	75-300mm Anti-Shock Mode
300mm f/4 Pro Silent Mode	75-300mm Silent Mode

To back-up our findings, we re-shot a series of tripod-based tests with the 300mm ƒ/4 Pro against the older Olympus 75-300mm ƒ/4.8-6.7 II at 300mm in order to rule out any issue with the 300mm Pro lens itself. Testing both with and without IS enabled, we shot a series at 1/80s with both lenses, and we found that with either lens, using Silent shooting mode produced the sharpest images. We observed shutter-shock blurring with single-shot and anti-shock modes from both lenses.

사일런트 모드에서 가장 낫습니다.안티 쇼크 활성화시켜도 약간의 블러가 발생합니다.

While the Olympus 300mm ƒ/4 Pro is certainly a very sharp lens, care should be taken to either use a faster shutter speed or opt for Silent mode (or Anti-Shock mode at least) if critically sharp images are desired.

Image Stabilization
One of the more notable new features of the Olympus 300mm ƒ/4 Pro is the inclusion of lens-based image stabilization, a first for an Olympus lens. Prior to this lens, Olympus offered only body-based image stabilization, either 5-axis IS on cameras like the E-M1 and E-M5 II or 3-axis with the E-M10 II, for example.

Dubbed "5-axis Sync IS," the new Olympus 300mm ƒ/4 Pro combines the efforts of the in-camera 5-axis IS of the E-M1 and E-M5 II with lens-based image stabilization -- similar to that of Sony's recent 5-axis IS system and Panasonic's Dual IS. What's unique about the Olympus system is that, according to Olympus, it offers a massive 6-stops of image stabilization correction when used with a compatible camera body! With the 5-axis Sync IS, the lens IS corrects for pitch and yaw movements, while the body-based IS handles pitch and yaw as well as roll movements.

Right now, the Version 4.0 for the E-M1's firmware and Version 2.0 for the E-M5 Mark II provide full Sync IS compatibility. However, for those with older Olympus cameras or other Micro Four Thirds cameras, the lens itself will still provide a very useful 4-stops of stabilization correction.

In our testing, the Olympus 300mm ƒ/4 Pro's image stabilization using the E-M1 v4.0 was fantastic. Our lens technician Rob has quite the steady hand to begin with and, as you can see from our graph, was able to get about a 40% keeper rate of "Good" shots down to 1/60s of a second without any image stabilization. With image stabilization, however, not only was he now getting 100% keeper rates at 1/60s, he saw 100% of shots rated "Good" down to 1/15s! Going even slower, we still saw a handful of "Good"-rated shots (~30%) at a whopping 1s exposure time. At 300mm. That is incredible!

Why is the Image Stabilization system with the new Olympus 300mm ƒ/4 Pro so great? According to Olympus, one of the main factors -- in addition to new I.S. algorithms -- is the hand-selected, high-performance gyro sensor inside the lens. Not only did Olympus contract specifically for high-performance gyro sensors, but also each gyro sensor undergoes performance assessments in the factory. Then, Olympus themselves hand-selects the best-performing sensors to go into each 300mm lens. In other words, only the best of the best make the cut for the Olympus 300mm ƒ/4 Pro lens. Furthermore, each time the camera is powered-on, the in-camera IS gyro sensor and the lens's counterpart are calibrated against each other.

Conclusion 
The Olympus 300mm ƒ/4 Pro is one heck of a lens. Simply put. After a long time in development -- it was announced as "in-development" back at CP+ in 2014 -- the biggest, brightest supertelephoto lens of the Micro Four Thirds system is, well, not so "big" after all, physically at least. An impressive feat of engineering, the folks at Olympus have managed to shrink down a 600mm-equivalent supertelephoto lens, with a constant, relatively bright ƒ/4 aperture and image stabilization into a remarkably small, comfortable, hand-holdable, weather-sealed lens.

Like Olympus' other Zuiko Pro lenses, image quality from the 300mm ƒ/4 is thoroughly impressive on all fronts: excellent sharpness and all-around wonderful optical qualities with little to no distortion, aberrations or vignetting. What's even more impressive is the lens' stunning image stabilization. Combining lens-based and body-based I.S., the Olympus 300mm ƒ/4 Pro lets you capture handheld images down to shockingly slow shutter speeds. All this, plus impressive close-focusing capabilities, make the Olympus 300mm ƒ/4 Pro a stunning lens for the professional and advanced photographer looking for a top-notch wildlife, sports, stage performance and close-up lens no matter the weather or lighting conditions. It may be pricey, but this is one of the best lenses Olympus has made thus far.

다른 리뷰

▶http://www.creativeislandphoto.com/blog/the-olympus-mzuiko-300mm-pro-lens

▶http://www.mirrorlessons.com/2016/01/06/the-olympus-300mm-f4-pro-review/ 보케는 별로라고 느낄 수 있다.

첫인상[동영상]:https://www.youtube.com/watch?v=ujMueCcXTlk