In short, I don't feel the need to stop the lens down for better image quality. When you do stop it down one or two notches, sharpness and contrast get slightly better. Again, I think it's perfectly fine at f/1.8.

OM SYSTEM OLYMPUS M.Zuiko Digital 25mm F1.8 Black For Micro

Wide open, this lens is a complete stunner. After my first day of shooting in natural light, I concluded that there really isn’t any point in stopping the lens down. When a strobe was mixed in, I stopped it down or tried to get the light to output at f1.8 at ISO 200. Stopping the lens down makes it marginally sharper, but there really isn’t any point once again. At f4 you start to see diffraction due to the Micro Four Thirds size sensor. Color Rendition Now, there is a hint -- ever so slightly -- of some corner softness at ƒ/1.8, but it's so minor that it's hardly worth mentioning. However, stopping down this lens improves sharpness even more -- and across the entire frame -- especially around ƒ/4-ƒ/5.6. However, center sharpness remains excellent throughout the entire aperture range, from ƒ/1.8 onwards until around ƒ/16, when minor diffraction limiting softness appears. Despite its ultra wide-angle design, the M.Zuiko Digital ED 8-25mm F4.0 PRO lens is 72mm filter-compatible, allowing the use of PL or ND filters. This provides more versatility, potentially minimizing glare and reflections, and enhancing the final look of an image. Other FeaturesFor me this Olympus 25mm f/1.8 is a very welcome addition to the system. I like it more than the Panasonic 25mm, because it's cheaper, smaller, lighter and the aperture doesn't rattle. In real life image quality is about the same. Highly recommend standard lens! When Olympus first told us about their 25mm f1.8 lens, we were thrilled that they finally created one. For many years, the scene has been dominated by the Panasonic 25mm f1.4 which is a good lens in its own right, but isn’t the affordable option for many. But just because this lens is affordable doesn’t mean that it doesn’t deliver.

Olympus 25mm f/1.8 M.Zuiko Digital - Digital Cameras, Digital

But when you consider that it is a wider focal length, then you’ll get less bokeh at a given aperture, correct? Yes, but we didn’t find this to be a really big damper on the images that we created. While in line with this thinking, one can then make a logical conclusion that it’s tougher to get something out of focus with a Micro Four Thirds camera than it is with a full frame or APS-C offering–and they’d be completely correct. The lens offers no focus limiter and no image stabilisation, either. The latter is no big deal really, given that this is a fast wide-angle lens that allows hand-held photography in fairly low light without IS (not to mention that Olympus bodies offer in-body image stabilisation).So which 25mm prime lens should you get? I own the Olympus 25mm and have played with the Panasonic for a bit, so here are a few thoughts. Panasonic Autofocus is swift, silent and dead on. Noting moves externally and I think it's nice that the lens shares a 46mm filter thread with some other lenses for the system. It is worth nothing that this is a single test at a single focus distance. I have not had a chance to do a formal test at further focus distances, but this test was chosen to give a nice balance between focus distance and shallow depth of field abilities. Focus distance was approximately 0.7m, which is somewhat close, but well short of the minimum focus distance of both lenses (0.25m for the Olympus and 0.3m for the Leica). Full Scene – Olympus 25mm f/1.8 @ f/1.8 Full Scene – Panasonic Leica 25mm f/1.4 Summilux @ f/1.4 Sharpness However, when working with Olympus’s sensors, we recommend not boosting the overall saturation and instead doing it by color channel. Color Fringing The normal prime space in Micro 4/3 is becoming a crowded area. On the wide end of normal, Panasonic has had their excellent pancake design 20mm f/1.7 for years. They later released the Leica branded 25mm f/1.4 tested here. That lens has been a mainstay in the system for some time, and really the only choice for a 50mm equivalent lens with fast aperture and autofocus. Voigtländer has also had a player in this range for a few years as well, with the manual focus and very fast 25mm f/0.95 Nokton. Olympus has been strangely absent from the normal focal range until now, with the release of the 25mm f/1.8.