Is the 23mm F2 a bad lens?

Hi,

No, it's not.  Have a look at the many images posted from the lens.  And have a look at the lab test sites like Photozone, Lenstip, etc.  The lab tests confirm that the lens is optically well corrected for distortion, just like the 23/1.4.  They also show that it's resolution by aperture is quite similar to the 23/1.4.  Each lens has incremental advantages at different points - there's not much in it.

Many owners have reported that the lens is soft in the corners at f2 when focused at MFD.  That may be so, but it's an unlikely combination - no-one seeking sharpness at close range is going to choose f2.  It's more likely to be chosen to differentiate a central subject from the background and foreground and in that use, it won't matter.  The 23/1.4 won't focus as close anyway.

The only oddity about the lens is that in every comparative test with the 23/1.4, it seems to offer a slightly wider FOV.  No-one has confirmed whether the f1.4 model is actually 23mm, but opinion seems to converge on the f2 model being about 21.5mm.  Maybe that matters to you, maybe not.  It might (say) if you were considering whether to get the 18mm.  Small changes in FL make big differences to WA FOVs and 21.5mm is closer to 18mm than 23mm.

Don't overlook other advantages the 23/2 holds..... for the loss of only one stop - it's smaller, lighter, cheaper and sealed.  And takes much smaller filters and accessories.

Regards, Rod