Panasonic and Olympus are both idiotic companies. They are also frustrating as all get-out, most expecially Olympus. Panasonic is frustrating because both their cameras and lenses have problems. Olympus is frustrating because their cameras are very good, but their lenses have problems.
Both Panny and Oly have either announced or released wide-angle zooms in the past year. Panny released their 12-35mm last year, and Oly is releasing their 12-40mm later this year. Both of them are slow in the world of high-end glass. I find this ridiculous because their sensors are very small. Making bright lenses should be easy. They are not doing this because of greed.
The Sigma lens should have come out years ago, but, as always, the lens companies didn't want to release it. They make so much money from herding their chattle into their closed systems that the idea of giving them a good price for good equipment probably caused physical illness. Thankfully, the Sigma has finally let the cat out of the bag.
But I'll express my love for the Sigma in another post. For now, let's focus on how Olympus and Panasonic suck.
A common reprise from PanOly, and from their fans, is that the lenses are slower because size was a consideration. First off, that's total horse shit because no one who truly cares about photography would ever give up a stop of light for anything. It increases the artistic boundaries of the lens by an order of magnitude... ya' know, if art was measured in the decimal system.
Also horseshit is that the Micro 4/3 sensor is quite a bit smaller than APS-C — 25% smaller to be exact. That means that any lens that is designed for APS-C can be reduced by 25% to find the equivalent lens size for the 4/3 sensor. Obviously, this only applies to the optics. The conversion isn't entirely applicable since motors and whatnot don't scale linearly.
So let's compare lenses, shall we. The Sigma is 78mm wide and 121mm long. Reduced by 25%, we have a lens that is 58.5mm wide and 90.75mm long. It's also a stonking-heavy lens at 810g. And while the weight comparison isn't as accurate, let's apply the 25% to it as well to get a hypothetical lens that weight 607.5g.
The Panasonic lens is 67.6mm wide and 96mm when extended. I used the extended length because the Sigma is an internal focusing lens and has a set length. As such, the hypothetical Sigma lens is SMALLER, he typed in ironic bold & capital letters, than the Panasonic lens. It's a boatload heavier, though; the Panny only weighs 305g.
The Olympus is 70mm wide and between 84-94mm long (I can't find a measure of its extended length). Again, the Oly is larger.
This is not meant to be an absolute, irrefutable, scientific study. It is meant to illustrate that when Oly and Panny say they had to take size into consideration with their lens designs, they are lying. They are lying because they want more of your money for less of their product. In Oly's case specifically, they have this fantasy that their SLR Zuiko line will somehow come back to life and as such, they cannot compete with it.
It really makes me wonder how the hell Olympus managed to release the 75mm f/1.8. Was no one watching that lens designer when he accidentally green-lit a great lens?
Regardless... Olympus is better than Panny. Their upcoming 12-40mm will sell for $999, which would have been great if not for the release of the Sigma. In this, they have already shown more sense than Panasonic did with the $1300 price for their 12-35mm. Granted, they've gone and named their new lenses "Pro," which I'm sure has caused many a pro to chuckle at Olympus' presumptuousness.
I'm a fan of primes. I think most non-journalists and non-wedding photogs are fans of primes. That said, I can't deny the ease of having a zoom lens on me. I would like a zoom lens that doesn't limit me. The Sigma did that in a big way. I would like one for my 4/3 cameras, as well. But both me, and the few other 4/3 shooters who I know, the instant we remove our 25mm f/1.4 or 75mm f/1.8, we regret it.
Indeed, my GF1 has spent nearly its entire life with the 25mm f/1.4 on it. It's a compact camera that gives me wonderfully artistic capabilities. The 12-35mm Panasonic forced me to work very hard to ensure that my shots didn't appear to be from a very good P&S. The zoom didn't liberate my artistic vision, it restricted it. That is something that I could not tolerate.
So again — I know that I reiterate this like some sort of broken recording of an old man yelling at kids to get off his lawn — I will not buy any of these new lenses from Panasonic or Olympus. In fact, I'm not sure who would.
Actually, that's a very good question, and I mean it sincerely. If you are a serious photog and you own these lenses, why did you buy them and why do you continue to use them? Are you not at least a little upset that they appear to be artificially limited?