I guess that begs the question: if I have the Olympus 14-42 II, is it worth bothering to get the 14mm f2.5, or should I wait and get something like the 20mm f1.7 or another fast prime?
I'm not a big pixel peeper, and as long as the 14-42 a bit sharper than the the 18-55mm canon kit, that shouldn't bother me, but is the lens really worth the money, or should I save it for something faster?
If you have the Oly 14-42 IIR and feel the IQ is adequate, the most economical way to go wider is add a WCON-P01 0.79x converter, that turns the wide end of the zoom to 11mm.
I have both the 14-42 IIR and the P14. I wanted to go wider. Olympus had a $69 sale on the WCON-P01 in January and I quickly pulled the trigger. I initially intended to use it on my 14-42. It does what I want, getting 11mm on the wide end with acceptable IQ.
I'd read that someone adapted the WCON-P01 on the P14 and found that the IQ did not deliver. Out of curiosity, I wanted to see for myself. The recommended way to use a couple of rings and rubber bands are much too fiddly and not at all secure. Well, I thought what the heck, $69 was cheap enough for an experiment, I went straight ahead and used a thin strip of 3M double sided tape to securely attached the WCON-P01 to a $2 46-52 step up ring. The WCON-P01 screws easily and securely on the P14.
Contrary to earlier opinion, I found that the WCON-P01 + P14 combo that yields 11mm is surprisingly good. IMO it's the true poor man's bright ultra wide prime (11mm f2.5). On my copies of P14 and 14-42 IIR, I found that the P14 + WCON-P01 beats the 14-42 + WCON-P01 by a comfortable margin. In fact, it's not even close. P14 + WCON-P01 is sharper from edge to edge than the 14-42 IIR that this converter was designed for. You can see an example from this combo on my Flickr page (the dome shot). There are some minor CA; it took me one minute to remove using Aperture.