Gambian sidling bush
- Feb 25, 2017
Neither 12-60 is sufficiently well characterized to know the probabilities of these statements holding true across copies but they're not especially consistent with n = 1 measurements available (12-60 f/3.5-5.6, 12-60 f/2.8-4). So, unless you're planning to sell your copies to the OP, their experience is likely to differ. From what's known about copy variation among μ43 lenses and copy variation among lenses within other systems it seems unlikely the MTFs of the two 12-60s are significantly different across most of the frame at most focal lengths in a statistically robust sense (p < 0.05, generously, p < 0.01 is usually preferred). What seems guaranteed for the extra size, weight, and cost is mainly the extra stop.It is not appreciably sharper at the center than the Lumix 12-60 under 40mm, but from 40-60mm it is noticeably sharper at the center than the cheaper Lumix version. The Leica version is sharper in the corners at all focal lengths than the Lumix if that matters to you.
Additionally, measurements in other systems is there's a default 8% chance the long end will be sharper than the wide end (Cicala 2017b). There's also a decent chance any overall claim about corners won't hold for at least some corners at some focal lengths (Cicala 2017a).
While some people might insist on interpretations claiming important distinctions, I would say distortion, vignetting, and CA are pretty much interchangeable between the two 12-60s. So I would suggest, if one doesn't need the extra stop, what you're paying for in a functional sense is mainly some complex and not especially clear increase in the probability of getting higher MTF from the f/2.8-4. Personally, I don't need the extra stop. So Panasonic would have to radically improve their communication about the value proposition of the f/2.8-4 for customers for me to give much thought to spending 2.5-3x more on the f/2.8-4. Don't see that happening.
In modern lenses the metal is frequently a skin over plastic to encourage a presumption of all metal construction for marketing purposes. I don't know of a teardown of the 12-60 f/2.8-4 which would confirm or deny in this particular case but it's 320 g compared to the f/3.5-5.6's 238 g. Assuming constant density under a cylindrical approximation as a baseline, all but 10 g of the difference is explained by the f/2.8-4's larger size. Ten grams is 4 cm³ of aluminum, so I would tend to guess the f/2.8-4 is metal skin.Finally the Leica is an all metal build so it feels nicer in the hand than the Lumix, but I wouldn't be surprised if the Lumix version is more durable due to it's all plastic construction.
One would hope, given Panasonic's lack of repair support, that the f/2.8-4 would have higher reliability commensurate with its higher price. But I too am sceptical about this and wouldn't at all be surprised if the innards of the two lenses are fairly comparable. If they're close enough to reuse some parts there would be a cost incentive to do so, after all.