[Leica] 28mm Summicron vignetting

[freakscene at weirdness.com (Marty Deveney)]

It's not polarisation.  It's not mechanical vignetting - it's optical
vignetting.  Here:

http://www.leica-camera.us/photography/m_system/lenses/461.html

You can access the datasheet.  At f5.6 the 28 Summicron retains about 42%
of the illumination at the centre for saggittal structures - and that's
according to Leica.  It will be proportionally worse for wavelengths with
lower transmission as these are averaged figures for white light.  The
other factor that I've noticed is that scanned film can show higher
contrast in tonal ranges that do not have high contrast in normally (or
even abnormally) developed and chemically printed photos.  This sometimes
exaggerates the appearance of vignetting - luckily Photoshop can fix it
perfectly.

The Leica 28/2 is a fantastic design with incredible performance - but as
always there are some compromises, the biggest still being cost.  In
providing maximum contrast and resolution to the edges of a very flat
field, one priority the Leica designers chose was to make every element
do as much as possible - recent Zeiss designs have greater numbers of
elements, each of which contribute less to the final performance.  Some
are also slower, easiing the design restrictions.  The resulting lenses
have slightly more distortion in some respects, but resolve more detail
albeit with slightly lower contrast.  It's a difference in design
philosophy that makes a difference that only people who look really
closely will notice.  95% of photographers never eve think about it.

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