[Leica] potential image quality (2)

[Erwin Puts <imxputs@knoware.nl>]

Alan wrote:
I am not sure I understand the last sentence herabove though. How does the
"knowledge" of the potential performance of a lens add to visual impact of
picture taking ? If I need to shoot at f1 in order to get hand holdable
1/15 sec with a 50mm, well I've got to use a Noctilux, and I "know" that
the performance might be sufficient to get a useable image. The level of
knowledge in this case is the previous experiences on might have add of
similar situations and setups (I have never touched a Noctilux) and/or
credible experiences and tests shared by others. The latter seems to be
like one of the main objects of this list and of your site. But, as you say
yourself, it is difficult to believe statements proclaiming 'stellar'
quality in such difficult circumstances....
My answer:
To extent the Noctilux example. My testing tells you that at close focus
(=B11 1 meter) the Noct is not the at its best. At this distance you must
lower your expactations a bit and the "impossible" head shot might even
below a useability level. A closeup head shot could lose all its impact if
even the sharply focused plane is slightly soft. Or more to the point. At
full aperture the Noct can be prone to coma. This can be reduced by
stopping down one stop OR trying to take the picture with the lightsources
OUT of Focus as this really lowers the coma effects. The visual impact
might change dramatically if the image is not distracted by ugly
butterflies.
Every lens has its weak spots. Knowing them is being one step ahead to
pictures with impact.

Erwin