Olympus 30 mm f/3.5 macro
Olympus announced in 2016 the 30 mm f/3.5 macro, its second macro lens for Micro 4/3 cameras.
The first Olympus Micro 4/3 macro lens, the 60 mm f/2.8 macro, has been around for a few years. It is a good lens for general macrophotography, and doubles as a medium-tele for portraits. It is a "premium" lens (i.e., positioned by Olympus between consumer and Pro lenses) and only moderately expensive, and lightweight enough to carry it in a camera bag most of the time. There are macro lenses of focal lengths between 50 and 90 mm for other camera systems that provide a better image quality than the Olympus 60 mm, especially in terms of good image resolution in the corners and optical correction of chromatic aberrations across the whole frame. Most of these lenses can be used with manual focus and manual aperture on Micro 4/3. I discussed on this site some of the alternatives for macrophotography for Micro 4/3 cameras. Especially for studio use, the Coastalopt 60 mm Apo f/4 is the best such lens in my possession.
30 mm is a short focal length for a macro lens (regardless of sensor size), because at a given magnification it forces a closer distance between the front of the lens and the subject than a lens of longer focal length at the same magnification. If one uses the conceptual approximation of a thin ideal lens, at a magnification of 1x a lens of focal length f is placed at a distance of 2f from the sensor and another 2f from the subject. This is only a rough approximation for a real, multi-element lens, especially if it uses internal focusing. In the latter case, close focusing is usually accompanied by a shorter focal length than when the lens is focused at infinity. This further decreases the working distance of the lens, compared to a macro lens of constant focal length (e.g., legacy macro lenses without internal focusing and floating elements).
This is particularly evident in the Olympus 30 mm f/3.5 macro, which at maximum magnification is only approximately 14 mm away from the subject. This greatly increases the risk of inadvertently hitting the subject while framing and focusing, especially when hand-held, and makes it difficult to satisfactorily illuminate the subject. This is especially so because the front of the lens is unnecessarily wide, with a 46 mm filter mount surrounding a front element with a diameter of only 12 mm.
This lens is unusual for the fact that it does not stop focusing at a magnification of 1x, and insted reaches 1.25x. On Micro 4/3, this means that the subject area is as little as 13.8 x 10.4 mm, quite enough for a large ant or similar subject, and too small to completely cover a bee or wasp. On a 36 x 24 mm sensor, you would need to reach a magnification of 2.5x to cover the same subject area.
As a whole, such a short focal length has disadvantages, especially near the high end of its magnification range, as discussed above. On the other hand, this focal length also has advantages:
Depth of field (DOF) at a given magnification and aperture is independent of focal length (despite common statements to the contrary). Therefore, DOF is not a factor in the choice of focal length of a macro lens.
Focal length does matter in other respects. Different focal lengths do provide a moderately different perspective rendering: a background distant from the subject is rendered as smaller with a lens of shorter focal length. This is not as important as it might seem at first sight, however, because such a background is in any case massively out of focus at any useful aperture. Another consequence of this phenomenon is that a lens of longer focal lengths captures a larger portion of the surface of a spherical subject. A telephoto lens, in particular, captures almost half of the surface of the sphere, while an extreme wideangle, at the same subject magnification, may capture as little as one-quarter of the surface. This is not as big a problem as one might expect, since a lens at 1x (assuming no change of focal length) has only half the angle of view than it has at infinity.
This 30 mm lens is not part of the Pro series, but is nonetheless a Premium lens. It does not have weather seals, and therefore is not moisture- and dust-proof. As a result of this, of the small diameter of some of its optical elements, and of the plastic barrel and internals (the lens bayonet seems to be the only significant metal part), this lens is remarkably cheaper than other macro lenses, even third-party ones. It costs roughly 200 US $ less than the 60 mm macro.
Focusing is internal and by wire (i.e. there is no mechanical connection between focus ring ad internal focusing helicoids), and there is no MF/AF clutch or switch. Therefore, it is not possible to change aperture or to focus unless the lens is attached to a Micro 4/3 camera, and the camera is powered on.
There is no distance and magnification scale, either. This is a problem for macrophotography for scientific illustration purposes. The magnification and focus distance is not recorded in the EXIF data, either.
The lens has no focus limiter (although a configurable focus limiter is available in some Olympus bodies, and works with this lens). There is no accessory button on the lens, either. The focus ring is the only control on this lens.
No lens shade is included with this lens. Field tests show that this lens is sensitive to flare when sunlight directly hits the front element.
When shooting in the close-up range or at longer distances, you may use a third-party, cylindric 46 mm lens shade mounted on the filter thread. However, this filter and lens shade size is simply too large for a lens with such a small front element and an angle of view comparable to a 60 mm FL on full-frame.
The size of lens shades, including cylindrical ones, corresponds to the size of the thread that screws into the filter mount of the lens (lens shades that fit on bayonet mounts are instead specific for a given lens model). The actual diameter of the lens shade at its front is typically between 3 and 10 mm wider than the mount. Most metal lens shades have a female filter thread of standard size at their front, to secure a butterfly cap at this end. This thread allows mounting a step-down filter ring at the end of the lens shade, to reduce the size of the front opening if necessary. See the following links for a general discussion and a practical example:
While a 46 mm lens shade is adequate for the 60 mm macro, it must be kept in mind that the best results are always obtained by using a lens shade just as wide as necessary to avoid vignetting. On the 30 mm, I use a 28 mm lens shade mounted on a 46 mm to 28 mm step-down filter adapter (or a stack of two adapters, 46-37 and 37-28, which are easier to find and make the lens shade slightly longer, which is good when working distance is not a problem). The 28 mm lens shade has a female 37 mm filter mount at its end, and it causes no visible vignetting even at infinity. Mounting a 37 to 28 mm filter adapter at the front of this lens shade does cause vignetting, so the lens shade is adequate as is, and provides a much better protection against flare than a 46 mm lens shade in spite of being shorter than the latter (which is an additional advantage at close range). The 28 mm lens shade can still be used at up to about 0.4x without interfering with subject illumination.
28 mm is the smallest diameter easily found in lens shades. For experimenting with lens shades of smaller diameters, my first thought would be trying extension tubes for C-and CS-mount lenses.
The optical scheme uses 7 elements in 6 groups. One elements is aspheric, a second element has dual aspheric surfaces, a third element is aspheric and made from extra-low dispersion (ED) glass. The rear element is as wide as allowed by the rear lens mount.
The image quality is high, with excellent performance at the center of the frame and good performance in the corners even fully open. As expected, this lens reaches its optimum around f/8 and is still usable at f/11. Don't go above f/11 unless you absolutely must. There is some darkening of the corners at f/3.5 that largely disappears at f/5.6 and above. There is also some transversal chromatic aberration, largely corrected in-camera by recent Olympus camera bodies.
Autofocus (AF) with the 30 mm on the E-M1 Mark II is much faster than with the 60 mm macro, in spite of the lack of a focus limiter in the former lens. While the 60 mm normally needs to hunt two or three times in interiors lighting before locking focus, the 30 mm only hunts once in my tests. AF performance in low light and/or on low-end camera bodies may be worse. In general, the E-M1 is more likely to focus hunt than the E-M1 Mark II, and this behavior is observed also with the 30 mm.
AF operation of the 30 mm is fastest with distant subjects (0.5-1 s in interior lighting), and significantly slower in the macro range (up to 2 s). This is also observed, to a higher extent, with the 60 mm. Neither lens is an AF speed demon, but the 30 mm is closer to fast AF lenses than the 60 mm.
My wish list for future Olympus macro lenses
I bought this lens for my own use, even though I do recognize that it has a few shortcomings. At this price, and considering the good image quality and minimal size and weight, I simply could not pass it up. Nonetheless, I have two main wishes for future Olympus macro lenses:
This could easily be done by shortening the focus ring, moving it backwards, and making the front part of the barrel a cone tapering down to a narrow front end. The rest of the barrel could also be reduced in diameter by a couple of centimeters except for the lens mount, since at present its interior is mostly a hollow, empty space. If anyone still wants to use a filter, a 25 or 28 mm mount is enough.
Several legacy bellows lenses (Canon 20 mm f/3.5 and 35 mm f/2.8, Minolta 100 mm f/4 MD, Minolta 50 mm f/3.5 Rokkor-X, Olympus OM 20 mm f/3.5 and f/2, Olympus OM 38 mm f/3.5 and f/2.8, Leitz Photar 25mm f/2 and 50 mm f/4, Zeiss Luminar 16, 25, 40 and 63 mm) and a couple of modern ones (Yasuhara Nanoha X5 once its LED illuminator is removed, Mitakon 20 mm f/2) have a narrow, often tapering front of the barrel, which allows a satisfactory illumination of the subject at low working distances. Olympus should be aware of this, since they made four such lens models in the past, as well as many microscope objectives. As it is now, the design of the front of the 30 mm is just silly. If you provide up to 1.25x in a macro lens, you should also make it possible to use this magnification in practice. Canon made a similar mistake with the otherwise interesting MP-E 65 mm f/2.8, and Minolta with its now rarely seen AF 3x-1x 1.7-2.8. Actually, both of these lenses have longer working distances at 1.25x than the Olympus 30 mm.
With the 30 mm, 60 mm and 120 mm macro lenses, Olympus would have a complete range of macro focal lengths. The Olympus 300 mm f/4 Pro additionally provides excellent close-up capabilities, which I am often using, for instance, with skittish subjects or to photograph wild flowers without kneeling down in mud or stepping down from the boardwalk in natural preserves. With the addition of a 120 mm macro (which of course would also be a good telephoto lens for general photography, lighter and smaller than the present Olympus 40-150 mm zoom), the existing lenses would cover almost all the thinkable applications in macrophotography up to 1x.
As a matter of fact, with the 30, 60 and 120 mm in my bag, together with the 7-14 mm f/2.8 zoom and perhaps also the 300 mm f/4, I might even consider leaving at home the 12-40 mm and 40-150 mm zooms (or my favorite alternative for the latter lens, the Olympus 50-200 zoom for 4/3).
Working at high magnification with the current 30 mm
As already discussed, the front of the barrel, with a diameter of about 50 mm, makes it impossible to illuminate the parts of the subject facing toward the lens. This problem is made worse by the rim of the filter mount. There is no good workaround. It might be possible to mount a thin, custom-built LED ring illuminator onto the filter mount of the lens, but ring illumination is not optimal for many subjects, and difficult to adjust for a pleasant modelling of three-dimensional subjects. LED illumination is also not always appropriate when a high color fidelity is required.
The very short working distance makes it impractical to mount a beam splitter for axial/paraxial illumination between lens and subject. The only remaining alternative I can think of is mounting a diffusing reflector on the front of the lens, within the filter mount. This reflector must be ring-shaped, with a central hole for the lens front element. With illumination coming from the sides (and preferably also obliquely from the rear) of the subject, this reflector fills some of the shadows left on the part of the subject facing toward the lens. This is not as flexible as a proper directional illumination unrestricted by the lens barrel, and not quite as effective as a proper Lieberkühn reflector (which, however, has several limitations) but still better than nothing. This type of reflector could be further enhanced by directly illuminating it with light guides. Incidentally, Olympus did make Lieberkühn reflectors for its 20 and 38 mm OM bellows lenses.
The reflector may carry at its center a short cylindrical lens hood of diameter slightly wider than the front lens element (an inner diameter if 18-20 mm should be enough for a short lens shade), to reduce the chance of flare. This lens hood can be made from a short length of black plastic pipe or rolled up black cardboard and glued at the center of the reflector. The reflector needs to be directly illuminated by the light source, but the front element of the lens must not be, and this lens shade works better than a plain central hole in the reflector to prevent direct lighting from hitting the front element.
A removable reflector could be cut out from thin aluminium sheet of the type used as a reflector in light armatures, and held in place within the 46 mm filter mount with the retaining ring of a 46 mm filter, without reducing the working distance. It is also possible to mount this reflector in an empty 46 mm filter ring for easier removal, but this wastes some of the already minimal working distance. A simpler, semi-permanent reflector can be cut from self-adhesive aluminium sheet used to protect kitchen furniture from heat radiated from the stove (sheets with interesting surface patterns, potentially effective as diffusers, are available), or even self-adhesive aluminium tape (which can be crumpled to obtain a diffusing texture).
Further experimentation could be made with larger reflectors, asymmetric reflectors designed to work best with directional illumination, as well as reflectors with a slightly concave surface facing the subject. Very convex subjects, or subjects with deep cavities that tend to remain too dark even with paraxial illumination, are likely to remain a problem.
Olympus could make such a reflector from vacuum-injected plastic at a very low cost, and give it away together with the lens to show that they really care about their customers.
Focusing in practice
As an alternative to manual focus, it is possible to use the LCD touch screen to select the autofocus area with a fingertip. This method is particularly effective when used with the cameras with best AF performance (mainly E-M1 Mark II). Single AF should also be selected, since this lessens the risk of focus hunting. The illumination level, if possible, should also be high enough to reduce the risk of focus hunting.
The 30 mm as a first macro lens
Would I recommend the Olympus 30 mm macro as a first macro lens? Not unless your application is mostly wild flowers and plants in the close-up range, or product photography of subjects larger than 15 cm or so, and you will rarely or never need magnifications higher than 0.5x. For living insects and/or subjects smaller than about 5 cm, the 60 mm is a far better choice. The lack of a magnification scale in the 30 mm is also a serious handicap.
The Olympus 30 mm f/3.5 macro is optically a good lens, capable of respectable image quality at a surprisingly reasonable price. The 30 mm focal length is suitable for product and wildflower photography, but too short for insect photography. Although this lens can focus to 1.25x, the wide lens front makes it exceedingly difficult to properly illuminate subjects at 0.5x and higher magnifications. It is further handicapped in scientific applications by the lack of magnification scale.