On Mon, 16 Dec 2002 22:43:12 +0100, "Niels J. Larsen"
>"Neuman - Ruether"
>news:3dfee306.4720452@newsstand.cit.cornell.edu...
>> >Regarding the 50mm I don't see anything at all that should indicate bad
>> >macro performance, sorry.
>> There is nothing there - it is assumed that people
>> know that fast lenses, asymetrical lenses, etc. (without
>> CRC) generally perform poorly outside their design focus
>> ranges (and sometimes even within - which is what I do
>> mention at www.David-Ruether-Photography.com/slemn.html).
>Do you have any links to places where I can read more about this and lens
>construction in general ?
>Maybe some general guidelines as to what I can expect (bad corner sharpness
>etc.) ?
No - the best "teacher" is experience... Try various things
and see what does/doesn't work for you. I've noticed that
many people think a lens is sharp if something somewhere
in the image is sharp (while most of the image area may be
soft, even if in focus...); others insist that the lens
is not sharp unless all parts that are in focus are sharply
imaged (I fall into the latter category...;-). *In general*,
the center of the lens' circle of coverage will be the
sharpest, with the edges the least sharp - and the edge
performance will decline first with "improper" use...
>This thing about bad performance - is it something that will make the
>pictures absolutely horrible to look at (remember I'm still a newbie) or
>will it be acceptable and - again considering the cost difference between
>the tubes and a true macro lens - something I could use to evolve my macro
>abilities until I can afford a true macro lens ?
Almost all image ills can be concealed, or even made into
"advantages", with skill - but it is easier to use gear that
requires the fewest "workarounds" to produce good
image quality under the greatest range of conditions.
On a tight budget, explore what can be done with low
image quality used well - even a $2 magnifying glass can
be used to make a great photograph (but it takes a LOT of
skill to do it...! ;-). Pinhole cameras are cheap and easy
to make - and some people use them to produce art... You
don't need the best gear to make good images, but do not
expect poor gear to be able to do all that good gear can
do... (a tube or close-up lens on a 50mm f1.4 will not
produce an image that is sharp at f1.4 anywhere but
*possibly* in the center - but this can be used to
advantage in making an image you may want to keep...).