I don't know how not to offend the fanboys with this one. I'm really disappointed with Olympus' lenses for micro Four-Thirds cameras. While I can appreciate the desire for small equipment, compromise is better left to other companies that have more fanboys.
This may seem nonsense to someone who had never used the Four-Thirds High Grade and Super High Grade lenses. Their standard series was, shall we say, sufficient for many people.
I'm not a snob about equipment, but I'd rather not risk my equipment on weather or dust. When I originally bought my Olympus E-1 in April 2004, Olympus only had weather-sealed lenses for Four-Thirds. I bought the ZD 14-54mm f/2.8-3.5 and the ZD 50-200mm f/2.8-3.5. Those aren't huge maximum apertures but they worked well enough, and the lenses used a 67mm filter. I used the 50-200mm during three of the four hurricanes in 2004 and never bet against the seals. I shot, I dried and repeated as necessary. The lenses work quite well to this day, and so does the E-1.
The only Four-Thirds lens I have that is not weather-sealed is the fairly expensive Leica/Panasonic 25mm f/1.4--the normal lens. You figure US$500 for a normal lens with an f/1.4 maximum aperture and twice as much for one that can be used wide open, unlike those from Canon and Nikon that have to be stopped down to get good sharpness. This one comes around US$1000 and works well wide open, as do the HG and SHG lenses from Olympus. It works as expected, except that I'm concerned that it might rain.
Now, with my journey into micro Four-Thirds, I have to pick lenses much more carefully, as though I was shopping for Canon or Nikon equipment. I prefer simpler choices. Currently, Olympus offers a great 60mm macro lens and the craptacular 12-50mm zoom. Yes, I get it, at 12mm any lens will distort more than a lens at 14mm. You have to use a more expensive lens design to get around it. The 12-60mm f/2.8-4.0 Four-Thirds lens distorts apparently terribly but they were more concerned with the focusing speed than the optical characteristics, it seems.
Panasonic offers two weather-sealed lenses at the moment: the 35-100mm f/2.8 (US$1499.99) that I have and the 12-35mm f/2.8 that I don't need. Both are rather expensive for the plastic-y bodies, Made in China, compromises that they are. (Supposedly, the 12-35mm isn't a Made in China product but are they all from one country or the other?) As I've been saying, the 35-100mm doesn't really seem too much worse than what you get from Canon or Nikon--you stop down the aperture to get good sharpness. Since many people are switching from those brands, they'll probably be okay with the compromise. Given that the sensor in the GH3 is better than the one in the E-5, I can live with that under low light circumstances. However, compared to the ZD SHG 35-100 f/2.0, Panasonic's lens is not very good at all but then, I don't really have much faith in the Canon or Nikon 70-200mm either, though my opinion of the Nikon lens is more positive.
Olympus recently created a second generation of a 75-300mm lens that needs very bright light to be useful. The maximum aperture is f/4.8-6.7. If I was using it to photograph birds, I'd hope that they'd be out in the open sunlight. More likely, I'd be using the ZD 50-200mm lens with the 1.4x teleconverter and the E-5. I just don't understand where Olympus is going. Several people have brought up the point that Olympus is no longer including lens hoods. Most of their fanboys probably won't need them, even though they should be using them. I don't carry the 35-100mm f/.0 lens hood with me because I need another bag for it and for the lens hood for the 14-35mm f/2.0. They're that big. I'm actually carrying both in the lens bag for the 35-100mm since I don't dare use it for the lens.
If Olympus would deliver the 12-40mm zoom lens (September 2013 announcement?) for which a patent was recently shown, and the aperture was sufficiently large, I would likely buy it, given that it was better than the 12-50mm they already have. I've seen professionals do good work with that lens, but getting around its flaws may be too much work for me. The 12-40mm is a larger range to my current ZD 14-35mm but if they stick to their "small and light" philosophy, it will have too many compromises, most likely. Should you pay over US$1000 for compromises?
Update 2013.07.08: DxO does testing on certain lenses to help with their raw development software. They just profiled the m.Zuiko 17mm f/1.8 lens. As many reviews have already stated, it's not very good, but it's nearly half the price of the great lenses. It's somewhat better than the 17mm f/2.8 lens but that was really horrible from what I've seen. If the Chromatic Aberration is so strong that you don't have to look for it to find it, that's a lens that should never have been made--Quantaray, anyone?
I guess that makes me think about a new Four-Thirds body or at least one that will use the lenses to full capacity. It's been rumored to be announced and/or available in the autumn of 2013. I'll keep hoping.
Update 2013.08.20: How about a craptacular, tiny, Frankenstein's creature of a camera body for Four-Thirds users? I'll look at the E-M1 but at this point, I cannot see wasting money on something that will not be well-balanced with my 35-100mm f/2.0 lens. I'm not asking for something the size of the E-5, but the size of the GH3 or E-1 would be appropriate, not the size of the E-M5. I'm not looking to replace an E-410 or E-510, or E-620. They were too small and they weren't meant for what I do. They were casual camera bodies, which is why they were replaced with micro Four-Thirds. Those people seem pleased with the performance. I wish I could be. The GH3, like the E-M5 is good enough for professionals, who aren't in a serious hurry. Still, with the 12-40mm f/2.8 lens, things are looking up.
Update 2013.10.30: Looking back on this, I need to say that I'll have a 12-40mm on order. The E-M1, while good, was not a replacement for my E-5 or my E-1. Yes, the image quality is wonderful, but the handling is completely wrong for me. It's about the same size as the GH3 but the grip was completely uncomfortable and it's not enough to easily allow me to use my ZD 35-100mm f/2.0 with it. I can't take a tripod or monopod everywhere I have used the thing handheld. The E-M1 looked better in person than the original photos I saw that seemed to show something cobbled together out of the parts bin. If they'd put the goodness in the GH3 body, they'd have a sale.
The 12-40mm f/2.8 gives me hope for the 40-150mm f/2.8 lens, as the 12-40mm f/2.8 was wonderful.
Update 2014.04.10: I got the Olympus 12-40mm f/2.8 not quite two months ago, and it has been attached to the Panasonic GH3 almost all the time. I have been quite happy with the combination, and it has given me hope that Olympus has found their way again, and that the GH3 is good for still photography. The color of the 12-40mm is much better than Panasonic's problematic 35-100mm f/2.8 lens that I also own. I'm sure I'll be replacing the GH3 as soon as I can trade it for the GH4. I have two Four-Thirds bodies and don't wish to repeat this with micro Four-Thirds.
The only problem with the "PRO" model lenses from Olympus is that they'll be slow in delivering them. The 40-150mm f/2.8 will arrive later in 2014, but the 7-14mm f/2.8 and 300mm f/4.0 will arrive in 2015. That still leaves a hole for a 150-300mm f/2.8, which is a lens I would truly like to have--a lightweight 2x zoom with a lot of reach. It could be the sharpest lens Olympus will have made for micro Four-Thirds, somehow looking toward the Four-Thirds 90-250mm f/2.8 but without the down-payment-for-a-house price.
Update 2014.11.14: As the 40-150mm f/2.8 is available, along with its 1.4x teleconverter, things are moving along. In previous years, I'd be buying this lens, and possibly the combination of the two, very early to support photographing swim meets. I haven't been photographing typical high school sports this year, but have been at skate parks.
There are times when I need a longer lens. I have occasionally used my Olympus 35-100mm f/2.0 on my Olympus E-5. (It's too much for the E-M1 and even for the Panasonic GH3 or GH4, which handles many Four-Thirds HG lenses well.) Using the 40-150mm f/2.8 could be useful when not able to move from a spot but it's not all that a wide angle. Using either the Olympus or Panasonic 35-100mm lenses, I find that there is no perfect lens for what I'm doing. Are two small bodies hanging from my neck a good idea?
I'm even more interested in the 7-14mm f/2.8 that's supposedly coming in 2015. I'm not a landscape type of photographer, but there are several occasions when I don't have enough of an angle to get everything. The 12-40mm f/2.8 has been good but it's not always enough. My typical thoughts were to buy a camera body with a larger sensor for occasional needs such as this. How many occasional needs will I have that I should spend US$4000 for a 135 Format combination or even US$3000 for a FujiFilm X-Mount combo?
In any case, Olympus has finally come to the table with some better than good options. Similar to the Four-Thirds days before the E-5.