Hi--

>15mm f3.5 4 (2) poor corner performance in B & W, good in color.
>
>Please forgive me if this seams a really stupid question but I can not see
>how a lens can perform better in colour, sorry color, than b&w.
>
>By color do you mean slide or negatives.
>
>Your mostly confussed
>abdo.
Abdo_Thabeth@bdo.co.uk

It is still a mystery to me, but some lenses, mostly superwides,
are noticeably different-performing (and using color filters
on them with B & W does improve their performance). The most notable
example is the 15mm f3.5, which has really poor corner performance
even well stopped down with B & W film (it is much better with even
a medium yellow filter on), but is OK with slide film (and probably
color negative film too). The 18mm f3.5 shows this less, as does the
oldest 50mm f1.4, but even the 20mm f2.8 shows some of this effect.