In a message dated 4/24/99 7:53:52 PM Pacific Daylight Time,
tomokoy@xxxxxxxxx writes:
<< I did not think seriously of how the specs of black might affect, so I
shot blooming flowers in my neighborhood. The result was that I could not
detect anything different with the 50mm/1.4 from the 4x6 prints. Carroll
Conway
thinks that the black specs are paint chips from the inside walls of the
lens.
He suggested that perhaps if I shoot a blank white paper with the aperture
wide
open at close range, the specs might show up as a shadow.
>>
Tomokoy,
I don't think you have anything to worry about if they are
paint chips as I remember reading an article from a photographic book from
the turn of the century, in which they recommended painting surface bubbles
in the glass lenses over with black paint to stop light scattering (which cut
contrast.) Claiming the paint had no effect on lens quality. Interestingly,
old large lenses almost always had included bubbles.
Another view : just think how large a black (paint) hole the centre
hole of a mirror lens is!
Probably the most likely lens/situation in which one might start to
see an image would be with a very short focal length lens set to focus close
so that the chips start to get within some range of being near focus.
Depending on where the chips are relative to the diaphragm ,stopped right
down may be worse than wide open since depth of field is greater.
If you want to try hard to see an effect with your lens you might try
using extension tubes and focusing close.
Tim Hughes
Hi100@xxxxxxx
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