Soenke Jansen wrote:
> Shawn Wright wrote:
>
> > I may be wrong, but I seem to recall my old OM-2 manual mentioning a
> > built-in
> > reciprocity adjustment for long exposures...
>
> I just browsed through my OM-2 (no n) manual (well, the german version
> that is, Dec77). Couldn't find any mention of the word reciprocity at
> all. Even worse, roughly translated they state: 'Because the OM-2 allows
> automatic exposures of up to 60 full seconds, [....] you should put it
> on tripod'. Well, I've done exposures of ca. 5min with this camera on
> auto and I certainly won't try to handhold them.
> Amazed about japanese manuals,
>
Franz Pangerl, in his book "The World of OM Systems" reckons that it is because
of
the Silicon Blue Cells which do the measuring for OTF exposures (in the OM2 at
least). He reckons:...if the silicon photodiodes only receive weak measuring
currents [in low light exposures], then they react with successively extended
exposure. This produces an unintentional but useful side-effect - a partial
balance of the reciprocity law failure."
NB my square brackets.
Chris
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