AG writes:
>>Medium Format lenses are designed differently with different contrast
>>curves and intents. Even among the 35mm manufacturers there are great
tonal
>>differences between lenses of different manufacturers. What is
assumed to
>>be an inherent advantage of the larger sensor is actually related to
the
>>lens designs, not the sensor designs.
Brings up Moose's point about larger format having an inherent
advantage in producing images with narrow dof with very sharp plane of
focus with nice bokeh. From Nasse article the degree of blur at an
equivalent aperture and lens design
should be format independent. At some point as the the degree of blur
in the distant background is a f(physical aperture size) the larger
format lens is just easier to design. The nature of the blur however is
very complex and a f(residual aberrations) nature of the lens elements
themselves and many other variables previously discussed. Having a
longer FL for any FOV must result in substantial
differences in design priorities. Also as AG has harped on, apsheric
elements in modern complex zooms can muck up the bokeh: Nasse---
"If you look at this picture very closely, you can see another
interesting effect – all the defocused spot images contain a circular
structure. It is possible to recognise from this that the lens has an
aspherical surface as these surfaces are often not as smooth as a
conventionally polished lens. Particularly in the case of lenses which
are manufactured by pressing hot liquid glass it is possible to
recognise the traces of the turning process with which the mould was
manufactured.
It is possible to combine rotational and pivotal movements when
polishing spherical surfaces because the curvature of the surface is
the same everywhere; in this case no traces are left. In the case of
aspherical surfaces the curvature is variable and therefore demands
other processing techniques. Residual unevenness of these surfaces
becomes visible if a very small light source is reproduced very much
out of focus."
Nonetheless I would think some Zuikos and other OM mount lenses would
(did) enable Dawid to express his vision with excellent results. What's
wrong with the Z. 100/2 250/2 or even CV125 in OM mount for this type
of application?
Mike
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