[Leica] Information content, 2

[Erwin Puts <imxputs@knoware.nl>]

The second test was even more demanding, The Apo-Summicron was focused at
two meter at an obsolete computer motherboard wit a myriad of s small
etched lines, tiny capacitators with extremely fine colour rings on them
(to indicate its capacity), all kinds of small objects, round, square etc.
The smallness will be appreciated if give you the figure of 0.05mm to 0.3mm
as a measure for some of the objects. At 2 meter object distance we have a
reduction of scale of roughly 20. That means that the details on the
negative/slide will be 2/1000 mm to 15/1000 mm. The Summicron can easily
resolve 100lp/mm with good contrast, that is lines with a width of 5/1000
mm. The object details then fall just within and just ouside the recording
capability of the lens. But: the lens can resolve even smaller details with
lower contrast and so we need a new concept. A detail is clearly resolved
when the outlines are measurable and the distance to the next neigbour is
also measurable. A detail is detectable when you can see the object but are
unable to measure the distances or the scale of the object.
 At 10times again exceedingly fine detail is clearly resolved. And you can
detect that there are more details within the details.  At 30 times the
slide film justl resolves these additional still finer details, but at 100
times the grain pattern is so rough that the recording capacity of the lens
is too demanding for this film. The cneg film shows the same pattern, but
now at 100 times the very fine details are faded away in larger dye blobs.
Now we have the reversed situation.  The film when enlarged looses
information content. The slide film was of an older generation, but the
cneg one of the most recent ones.
So the choice of film is even more important now with these super Leica
lenses then it was in the past.


Erwin