The 12-100mm is a constant aperture f/4 lens that measures 116.5mm long by 77.5mm in diameter with a 72mm filter thread. Like all Olympus PRO lenses it has a programmable lens function button, a manual focus clutch and is weather-sealed, meaning it is splash proof, dust proof, and freeze proof. It has 17 elements in 11 groups with high quality construction and the Z nano coating to reduce glare. Perhaps most impressive is the 5-axis Sync image stabilization that works in tandem with the in-body image stabilization of the OM-D E-M1 Mark II to produce up to 6.5 stops of IS.
The chief reason why this lens has become a favourite of mine is the incredible focal range - the 35mm equivalent of 24 - 200mm. Presently, it is the only professional high magnification zoom to cover that range. The images below illustrate just what that looks like.
One of the biggest selling points of the Olympus mirrorless system is how compact both the camera bodies and lenses are without any sacrifice in image quality. Given the amount of time I spend hiking and paddling I love the fact that this lens allows me to go from wide-angle to mid-range telephoto.
The flexibility of this lens makes it an excellent choice for practically any travel situation. You would typically need two professional grade lenses to cover this focal range and at 21 ounces it is light enough to carry all day and have it easily fit into a small camera bag. With excellent optical performance you are definitely not sacrificing image quality.
Although the 12-100 makes for an excellent travel lens, it has also become one of my primary landscape lenses, for all of the same reasons. It is light, has great reach, is ruggedly built and has excellent image quality. As an avid kayaker and canoeist I really appreciate the fact that this one lens has so much flexibility for what I shoot. The Sync IS also gives me confidence that my images will be sharp even when bobbing around on the water.
Another impressive feature of this lens is the remarkably close focusing distance of only 15 cm when shooting at 12mm. When set at 100mm the minimum focusing distance goes to 45cm. Though not designed as a true 1:1 macro lens, it will certainly allow for some excellent macro opportunities.
Flexibility and versatility are words that clearly describe the appeal of this lens. As such, it can certainly be used as a good portrait lens. Now, it's unlikely that any professional portrait photographer would use the 12-100 as their primary portrait lens, but it can make for a great back-up lens. For other situations, like photographing my grandkids at the beach, it's perfect. With a constant aperture of f/4 the lens produces a pleasant bokeh when shot wide open, but of course, not as soft as you would get with a faster lens.
So how does the 12-100 handle low light situations? It is only an f/4 lens, after all. Remarkably well, I'd say. I do a lot of night sky photography and I have to admit that this lens has never found its way onto my camera for those situations, but for interior shooting or for capturing the city lights it does a fantastic job. With the Sync IS, that works in conjunction with the IBIS, I have never had any concern with shooting in dimmer light. All of the interior shots below were handheld and because of the fantastic optics and the exceptional image stabilization are incredibly sharp.
There are a number of lenses in my bag that I would have trouble parting with, but none more than the m.Zuiko 12-100mm f/4 PRO. I'm not going to repeat all of its excellent features. Suffice it to say that it has truly become my workhorse lens and will likely remain so for the foreseeable future.