I've thought about a 12mm prime but I've always decided against it because I don't tend to use that focal length for low light shooting and when using a length like that for good light shooting I almost always stop it down and once I've done that I might as well be using my 12-35mm f2.8 or even my 14-42mm f3.5-5.6.
I can see two advantages to the 12mm f1.4, low light and DoF. But then there's the cost.
A lot of my photos are buildings and transport in less than favourable lighting conditions
Also fancy a dabble at a bit of night sky photography, pretty free of light pollution on the RSPB reserve a ten minute wander up the road.
Been through the photos from my latest trip and quite a few are 12mm or 14mm, guess architecture is likely to be
Other option I am considering is a trade in for a 8-18 from either company, they are heavy though
It is apparently better, it is said to be sharper and it's got better magnification for close ups. I've never used the Pany 12-35 mk1 or II but I know my copy of the 12-40 was tack sharp at all FL and apertures. Lovely lens to use. But it still goes for cheaper on the used market, maybe because the Pany mkII is newer? But where you might see the Oly go for £400 or [actually, often] less, the Pany mkII often gets over 500 used. I sold my 12-40 for €400, which is about £350, and bar not having the box it was in excellent condition
Both have their pros and cons, Oly is definitely better at 12mm and Pana gets the nod at 35mm.
Not noticing the Dual IS making much difference, maybe if my camera had the newer Ver 2 it might be more significant.
The Pana is lighter and more compact, Oly is fairly front heavy so the smaller lens balances a lot better on my GX9.
Oly definitely better close up, there again I have a Pana 35-100 f2.8 so filter size of 58mm would be the same as the 12-35
Thought the 12-35 would focus quicker of the two on a compatible Pana body, but nothing in it at all
The colour and contrast is subtly different, think in my opinion the Pana is nicer, bit crisper if that makes any sense.
Really is a close call and not decided yet, got a TP meet in London coming up
Will try the newer 12-35 out then, usually a good variety of subjects so should be a fair test
No doubt daft getting the 12-35. but one of those things I had to try otherwise would have kept wondering which suited me best.
At the moment its the cheaper, heavier, bigger Oly in pole position mainly because its excellent at 12mm
I had the Oly 12mm f2 and the 12-40 is equally good, that was a surprise, but the faster 1.4 prime would be handy at times
Subject to change after a better evaluation, wish I could combine the two really
On the subject of price, I enquired at one camera shop with a number of branches for a trade in price on the Pana against a used 12mm prime
Derisory offer of £300 for an easily 4/5 condition lens, dread to think what they would value the 12-40 at?
I know they have overheads and all the other salient points, but some places are downright greedy too