[Leica] Hexanon. part 2

[Erwin Puts <imxputs@knoware.nl>]

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At f/2.8 the Hexanon has much improved imagery and now has a high 
contrast image on axis with a crisp rendering of very fine detail 
over an image area of 8mm.  The rapid falloff in quality in the field 
and outer zones is still there to be seen by critical inspection, but 
now fine detail is quite clearly visible with some fuzziness at the 
edges.
At f/5.6 the improvements continue and now the center area has grown 
to 12mm diameter, covering a large part of the negative area. The 
outer zones stay a bit soft. Very fine detail is now easily recorded.
At f/11 the maximum is reached and now exceedingly fine detail is 
clearly resolved with medium to high contrast.
The Hexanon produces imagery, reminiscent to classical lenses of the 
golden age of lens design for RF cameras when on axis performance was 
paramount  and the outer zones had to be a bit neglected, given the 
state of the art of design in those days. It will produce high 
contrast images with a crisp rendering of fine detail in the center 
of the image. The rapid drop of performance beyond this circle can in 
most situations be neglected as it will be located in the 
out-of-focus unsharpness zones anyway.
The Noctilux 1.0/50mm at f/1.0 (full aperture) is of slightly lower 
contrast than the Hexanon at 1,2. The on axis performance of the 
Noct extends over a slightly larger circle and very fine detail is 
recorded with a bit more edge sharpness. At f1.0 the Noctilux imagery 
overall is  slightly ahead of the Hexanon. One might call it a 
photo-finish. At f1.2 the Noctilux  forges ahead and especially the 
fine details are recorded with more crispness. The Noctilux  has the 
same characteristic as the hexanon in that the image quality drops 
fairly rapidly when going from center to corners. The Noctilux has a 
smoother gradient  and the fall off in performance is more gentle. 
The Noctilux however has a slightly higher level of  vignetting than 
the Hexanon.
The Noctilux at f1.4 improves quite a bit (the on axis area shows 
quite crisp rendition of fine detail over a circle of about 9mm) and 
high contrast, As this is the 'real' aperture to compare the Hexanon 
1,2/60 with, the Noctilux is now visibly ahead of the Hexanon at 
f/1,2.
It is very interesting to compare these two lenses as they show to 
what level aberrations of very high speed lenses need to be corrected 
for good imagery in their intended area of applications. The Noctilux 
is 'optically' a full stop wider than the Hexanon and it is quite a 
performance that the Noctilux can show off the Hexanon, albeit with a 
small margin, while wrestling with a much higher aberration content. 
On its own the Hexanon at f/1,2 is an admirable performer and shows 
that small concessions in speed and angle of view can circumvent the 
big challenge.

Erwin

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<fontfamily><param>Arial</param>At f/2.8 the Hexanon has much improved
imagery and now has a high contrast image on axis with a crisp
rendering of very fine detail over an image area of 8mm.  The rapid
falloff in quality in the field and outer zones is still there to be
seen by critical inspection, but  now fine detail is quite clearly
visible with some fuzziness at the edges. 

At f/5.6 the improvements continue and now the center area has grown to
12mm diameter, covering a large part of the negative area. The outer
zones stay a bit soft. Very fine detail is now easily recorded. 

At f/11 the maximum is reached and now exceedingly fine detail is
clearly resolved with medium to high contrast.

The Hexanon produces imagery, reminiscent to classical lenses of the
golden age of lens design for RF cameras when on axis performance was
paramount  and the outer zones had to be a bit neglected, given the
state of the art of design in those days. It will produce high contrast
images with a crisp rendering of fine detail in the center of the
image. The rapid drop of performance beyond this circle can in most
situations be neglected as it will be located in the out-of-focus
unsharpness zones anyway. 

The Noctilux 1.0/50mm at f/1.0 (full aperture) is of slightly lower
contrast than the Hexanon at 1,2. The on axis performance of the  Noct
extends over a slightly larger circle and very fine detail is recorded
with a bit more edge sharpness. At f1.0 the Noctilux imagery  overall
is  slightly ahead of the Hexanon. One might call it a photo-finish. At
f1.2 the Noctilux  forges ahead and especially the fine details are
recorded with more crispness. The Noctilux  has the same characteristic
as the hexanon in that the image quality drops fairly rapidly when
going from center to corners. The Noctilux has a smoother gradient  and
the fall off in performance is more gentle. The Noctilux however has a
slightly higher level of  vignetting than the Hexanon. 

The Noctilux at f1.4 improves quite a bit (the on axis area shows quite
crisp rendition of fine detail over a circle of about 9mm) and high
contrast, As this is the 'real' aperture to compare the Hexanon 1,2/60
with, the Noctilux is now visibly ahead of the Hexanon at f/1,2. 

It is very interesting to compare these two lenses as they show to what
level aberrations of very high speed lenses need to be corrected for
good imagery in their intended area of applications. The Noctilux is
'optically' a full stop wider than the Hexanon and it is quite a
performance that the Noctilux can show off the Hexanon, albeit with a
small margin, while wrestling with a much higher aberration content. On
its own the Hexanon at f/1,2 is an admirable performer and shows that
small concessions in speed and angle of view can circumvent the big
challenge. 


Erwin   
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