In a message dated 2/11/99 8:07:25 AM Eastern Standard Time,
Matthias.K.Wilke@xxxxxxxxxxxxxxxxxx writes:
<snip>
<< When you take a picture of a landscape
with a forrest in the background, and in this forrest some trees are
greater than the average trees, and these greater trees stand as a
silouette in front of a much brighter sky, then you can see sometimes such
tree "shadows" twice, if they are near the corner of the picture and small
enough not to overlay. The one shadow is dark and the second is much more
difficult to see, coloured and brighter. >>
<snip>
I agree this could be chromatic aberration. It also sounds like it may be a
ghost image caused by flare. Admittedly it's hard to tell from verbal
descriptions. If anyone wants to sell me an 18/3.5 Zuiko real cheap there is a
small forest behind my house I can use for testing ;-)
<<Such effects should be absent in apochromatic lenses.>>
Is this strictly true? My understanding is that an apochromatic lens is
corrected for three different colors (wavelengths). An achromatic lens is
corrected in two. Obviously an apochromat is better than an acromat in
correcting chromatic aberration, but doesn't eliminate it. Maybe if Olympus
develops a product from the gradient-index glass they are reportedly working
on they will *eliminate* chromatic aberration.
Paul Schings
Coventry, RI
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