On 27 Sep 2002 15:31:47 -0500, rmonagha@smu.edu (Robert Monaghan) wrote:

>I agree with you that non-retrofocus wide angles should have some optical
>advantages, which is why I was surprised to learn that the M5/6/? metering
>system required use of longer distances, and that meant creating
>retrofocus versions of the various leica lenses even for the M series.
>
>Leica now claims that their retrofocus lenses are even better or at least
>equal to the classic non-retrofocus designs of the past etc. This seems
>curious to me, as I'd expect more elements means more flare, at the least.
>
>in any case, you can use a variety of non-retrofocus wide angle lenses on
>SLRs too, provided they have mirror lockup, as the nikon 21mm biogon
>derivative and similar lenses have worked in the past etc.

But the 21mm Nikkor f4 non-retrofocus had far more
flare-tendency and illumination corner roll-off than
the sharper retrofocus 20mm f2.8 Nikkor does... It
does not surprise me that a "somewhat retrofocus"
design could have the best mix of design compromises,
since both design types (retro/non-retro) offer
advantages/disadvantages...