Saturday, October 22, 2011

Sharpness, resolution and grain of New55

A close crop of a fairly recent New55 PN negative processed for two minutes and cleared in ordinary hypo.  The Xenotar 150mm f2.8 is capable of very high resolution wide open, as it is designed to be used.  I measure about 120 lp/mm on the negative, just an estimate, which is somewhat less sharp than the 180 lp/mm claimed for old T55.  You can just see some of the grain coming up in the brass end of a little steam engine that was the subject of the day.

Around the periphery of the image, where there was a black background, some reversal occurred, but not in the center.  The spread of the reagent, and the exposure, determine how much development is left over after peeling.  It seems that no harm is caused by a longer development time, but we are going to use 2 minutes as the standard of comparison so we can detect changes as the design evolves.

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