Re: ACL/bolex lenses

["Robert Morein" <prolog3@netreach.net>]

Eclair ACL Discussion and Support

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----- Original Message -----
From: "David Brosius" <dmbro@swbell.net>
To: "Eclair ACL Discussion and Support" <EclairACL@listbot.com>
Sent: Friday, May 18, 2001 9:08 AM
> It's my understanding that it is the markings on an RX lens which are
> different;

Unfortunately, the difference is bigger than that.
A solid prism block, which reflex Bolexes have, add spherical abberation to
the lens path.

Spherical abberation refers to the particular optical defect which caused by
the fact that a lens is not flat; it has thickness, which varies from center
to edge.

An RX lens is designed with a correction for this.
Put it on a camera which doesn't have the prism block, and the result is an
optical defect in the reverse direction

The defect is a function of F-stop. If you close down an RX lens far enough,
the area of the lens exposed by the diaphram is approximately the same
thickness throughout. Hence you may find the results acceptable if you close
down to F5.6.


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