Samyang is going all-out with their latest releases, seeking to cover every conceivable focal length and user request. As with any other Samyang lens, the macro is the same optical formula across systems, with only the flange distance differentiating it for each mount. I used it on MFT and Fuji-X cameras, but, again, all results are relevant to any system (except where noted otherwise).
The lens is quite reminiscent of the 135mm: it is close to that lens' size and weight. In fact it is somewhat smaller and lighter, although not by very much. On one of the larger mirrorless cameras (preferably with grip), it balances well and creates no problems in handling. This will be true for virtually any DSLR too. It is hefty but up to the point where it inspires confidence and not becoming a burden.
This is a very well made lens, as we are used by Samyang lately. It's made from good quality industrial plastics and some metal components. I strongly disagree with those suggesting that Samyang would start using more metal: there is absolutely nothing wrong with utilizing alternative materials, that are as solid and lighter. The lens comes with a good quality hood and the usual Samyang cloth pouch.
In use, the lens is very precise and, eventually, easy and intuitive to use. The aperture ring has a satisfying click, while the focusing ring has as long a throw as needed. It is also very smooth in use; a very important parameter for any manual lens.
Turning our attention to the optical performance, we are by now accustomed to Samyang providing sharp, optically optimized designs. Resolution is on a high level, even from max aperture. This is particularly evident at the center of the frame, while the edges and corners are -naturally- inferior while wide open. Edges become very sharp from about f/5.6 and corners of the frame are excellent from f/8 or so. Let it be noted that we are nit-picking here, since, on most cameras, it will make little difference shooting at, say, f/6.3 vs f/8.
Let's also not forget that macro lenses are of very limited use as such, when shot at max apertures; indeed, they are mostly spend their life in the f/8 or smaller apertures. There is no way you can get any useful depth of field otherwise, except when using techniques such as focus stacking. Unfortunately, use of such techniques are not always possible on the field and are mainly limited to controlled (studio) environments.
A major demand from a good macro lens is its performance in terms of image defects; more precisely, lack thereof. We are happy to report that chromatic aberrations, both longitudinal and lateral, are virtually a non-issue with this lens. This is important, since such problems are not always easily fixed in post processing, with macro subjects.
As with almost all modern macro lenses, distortions are a non issue too. Vignetting on the other hand is present at max aperture, but not to a degree that would cause real-world problems. This will be evident with a FF camera, and it goes away from f/5.6 onwards anyway. A welcome characteristic of the lens is that it retains contrast and color from wide-open, and it resists flares and loss of contrast even when shot against strong light sources.
Another very nice attribute is the pleasant bokeh: this will certainly be important in the macro role, but also for those interested in using the Samyang at a secondary portrait function. Out of focus rendering never gets nervous or harsh and, although it cannot reach the performance of dedicated portrait lenses, it performs at a very high level when used in this fashion.
All in all, the Samyang 100mm f/2.8 macro performs as one would expect from a top level macro lens. The only trouble is, depending on the system, it faces very serious competition from other native or even adapted lenses. In the Samyang 135mm f/2 review, we concluded it currently is one of the best options regardless of system and holds its own against any competitor. The 100mm macro has a much more difficult job.
Competitor lenses for the Canon and Nikon DSLR mounts (either from Canon/Nikon or third party, from Tamron and/or Sigma) are, to be honest, quite superb. Not only that, but they also come in very competitive prices and are mostly AF. The latter is not a major issue with macro lenses, but it's desirable for many users. The Samyang, optically speaking, but also concerning build quality, plays somewhere at the middle to the top of the pack; unfortunately, most users will probably choose a brand lens while faced with this choice.
On mirrorless systems, things get more interesting. Currently, there are just one or two choices on each mirrorless mount, for macro lenses. Micro four thirds has two native options (Olympus 60mm f/2.8 and Panasonic 45mm f/2.8), Fuji and Sony have one each (60mm f/2.4 and 90mm f/2.8). Of course, in all these systems, one can adapt almost any macro lens from DSLRs or older film cameras.
On MFT and Fuji-X, where the lens was tested, the problem is that, existing native options are "short" macros, which limits them somewhat in some applications. For example, if shooting insects, focusing distance may be too close, and that may easily spook the critter. Having an equivalent 150mm or 200mm macro lens, with the Samyang, makes things much more comfortable. Let it also be noted that the Fuji 60mm f/2.4 is not a true 1:1 macro lens; this will be taken care of with a 120mm f/2.8 lens currently on the roadmap. Interestingly, as discussed above, this is a telephoto lens.
For these two systems, the 150 or 200mm focal length, especially at a fast f/2.8 aperture, is also quite useful for general photography. It makes for a very competent portrait lens, with no distortions whatsoever and great bokeh. It's important to note that, vignetting and sharpness characteristics are improved with the crop sensors.
As a final note, I would like to emphasize once again, how difficult it is to manually focus with a modern DSLR, using the optical viewfinder. In reality, I would consider it practically impossible with a macro lens, in real-life conditions. The only real option is using the live-view, effectively reducing the DSLR to a non-EVF mirrorless. That said, if the project involves a studio environment (tripod, lighting control, focus stacking), there is little problem, and the very precise focus control on the Samyang will prove both pleasant and effective.
Here is a small gallery of photos taken with the Samyang. Camera used is referred on each image caption. Apertures used were between f/8 and f/11 mostly (there were a couple of photos taken at f/4-5.6) . All photos were handheld and mostly using available light:
Once again, many thanks go to our friends at All About Digital Photo for providing the lens for testing.