Plugged In: Get sharp — optics are key in clear images

By Joe Kashi, for the Redoubt Reporter

A sharp lens’ crisp yet smooth rendering of detail has a unique look to it, suggesting a hyper-reality that’s almost tactile. You’ll need good optics to reach this higher level of image quality, though. Even the best post-processing software can’t enhance detail that’s not already there in some form.

As I’ve previously written, one of the prime advantages of the Micro Four-Thirds compact camera systems championed by Panasonic and Olympus is the wide variety of very sharp, affordable lenses. This week, we’ll take a hands-on look at some of these lenses. I’ll first describe the testing procedure because it taught me a good deal about making the sharpest possible images of static test subjects. Remember, to find the 35-mm equivalent magnification and field of view an M 4/3 lens, you must multiply its focal length by two.

While preparing these articles, I tested most of the lenses mentioned here. When specific lenses were not available for testing, I supplemented my own results with comparative data from http://www.dxomark.com, comparing general test results for both the unavailable lens and similar lenses that I personally tested. DXO, based in Paris, makes the hardware and software used by most lens and camera test sites around the world and publishes some of the most carefully measured and objective test data. That free, publicly available data allows anyone to directly compare up to three cameras or lenses against each other. It’s an excellent resource.

For these tests, I used a tripod-mounted Olympus E-M5 Mark II in both its standard 16-megapixel mode and its 64-megapixel, high-resolution, sensor-shift mode. The E-M5 Mark II, an updated model released two months ago, currently has the highest potential RAW file resolution capability of any affordable camera, higher than any current or announced full-frame digital SLR camera. That high-resolution mode is currently usable only on a tripod with unmoving subjects. You’ll need to use the lowest feasible ISO sensitivity to retain maximum detail. That’s particularly true with the somewhat smaller sensor found in M 4/3 cameras, so I used the E-M5’s base ISO 200 for all tests.

Camera shake and internal shutter vibration were further reduced by using an external cable release, a two-second shutter release delay and Olympus’ anti-shock mode. Our test targets were a stacked bookshelf about 20 feet away for the telephoto and a series of finely woven fabrics, complete with superfine German Shepherd fur, 5 feet away for the wide-angle and normal lens tests. Depth of field is wafer thin with telephoto lenses, especially at wider lens apertures and closer subject distances. Careful focus is critical as even slight focus errors will noticeably degrade sharpness.

All photos were recorded in RAW format. Both Lightroom 6.0 and DXO Optics Elite 10.4 now directly support the 64-megapixel, high-resolution RAW files made with the E-M5. One set of test files was imported directly into Adobe Lightroom 6. A second set of the same RAW files was first preprocessed for sharpness and noise reduction with DXO Optics Elite, and then imported into Lightroom 6 for final tweaking and comparison.

Generally, the files first preprocessed in DXO and then fine-tuned with Lightroom showed the best detail and lowest image noise. The DXO improvement was subtle with the best lenses, more evident with lenses of average quality. DXO does seem to increase contrast, overall exposure and highlights somewhat more than I personally prefer, so I tweaked the DXO-processed files to my personal preference in Lightroom.

I also found that the E-M5 files were somewhat overexposed, so I reduced all exposures by -.3 EV to -.7 EV. That seemed to improve overall sharpness and image appearance while providing a usefully faster shutter speed. Regardless of how processed, the new E-M5 does seem to have an impressive amount of easily recoverable shadow and highlight detail.

I made the majority of shots using Olympus’ 64-megapixel mode, presuming a lens that was sharp at superhigh resolutions would be more than adequate at lower resolutions. That proved true.

Lenses, particularly less-expensive lenses with lower quality control standards, can vary significantly between individual units. I had only one copy of each lens available for testing, so other results may vary. The sharpness of all lenses tends to vary with aperture. Generally, M 4/3 lenses are sharpest in the f/4 to f/5.6 range, so I used f/5 as a compromise. Where some zoom lenses had a dimmer maximum aperture at the extreme of their magnification range, I used f/7.1, about 0.5 EV smaller, because very few lenses have best sharpness wide open.

We’ll start with standard wide-angle-to-telephoto zoom lenses, the most common and frequently used optic. Most kit zoom lenses, including M 4/3 zooms, are adequate but not stunningly sharp.

v Olympus’ standard 14- to 42-mm II R zoom is very sharp on standard 16-megapixel images throughout its zoom range. In high-resolution mode, though, it’s acceptable at the widest 14-mm and 18-mm settings in the central part of the image, but not in the corners. Panasonic’s newest 14- to 42-mm kit zoom lens reputedly performs somewhat better.

v One step up are the Olympus 14- to 42-mm EZ electrically operated zoom lens, a weather-sealed Olympus 12- to 50-mm zoom lens, and a very compact Panasonic 12- to 32-mm optic. These performed on par with the Olympus kit zoom, although the Olympus and Panasonic compact models did somewhat better at wider angles, while the 12- to 50-mm Olympus did better at higher magnifications.

At their wider-angle settings, the Olympus 14- to 42-mm EZ and the Panasonic 12- to 32-mm were marginally adequate in high-resolution mode, but the Olympus 12- to 50-mm was not. All three lenses performed reasonably well in standard resolution. Overall, though, they performed somewhat lower than I had hoped for $300 to $500 lenses, fading more than expected toward the edges and corners despite acceptable central area sharpness.

v At a noticeably higher quality level are Olympus’ weather-sealed 12- to 40-mm premium zoom, which I tested, and Panasonic’s 12- to 35-mm, which I compared using DXO’s data. Both lenses are generally free from any significant fault and are widely used by professional photographers.

The Olympus is somewhat sharper across its zoom range than the Panasonic, but it’s larger and does not include optical image-stabilization hardware inside the lens. That makes Olympus lenses less useful for Panasonic camera owners, whose cameras do not contain the effective in-body image-stabilization hardware found in Olympus cameras. In testing the Olympus in high-resolution mode, I found its level of crisp detail often exceeded that of good single-magnification prime lenses, and that’s saying a lot. The Olympus zoom is simply an excellent lens that did well under the most demanding circumstances.

v My first preference, not surprisingly, is Olympus’ 12- to 40-mm zoom, followed by the Panasonic 12- to 35-mm and 12- to 32-mm models. Among inexpensive kit lenses, the Olympus 14- to 42-mm II R lens works surprisingly well, at least if you have a good copy.

Next week, we’ll take a look at quite a variety of telephoto zoom lenses and make some recommendations that may surprise you.

Local attorney Joe Kashi received degrees from MIT and his law degree from Georgetown University. He has published articles about computer technology, law practice and digital photography in national media since 1990. Many of his articles can be accessed through his website, http://www.kashilaw.com.

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