Re: M3 DOF in viewfinder?

[doctorc8@stout.entertain.com (Henry Chu)]

>I've seen several references to a quick way of assessing depth of field
>in the viewfinder of the M2 and the literature implies this is true of
>the M3 as well.
>
>The diagram shows what appears to be the central rangefinder patch, with
>different size "notches" at the top and bottom of the patch.  From what
>I remember, the near and far limits of depth of field can be determined
>when the double image of a vertical object falls within these notches.
>
>The problem is, my M3's rangefinder patch is a quite ordinary rectangle
>with no such notches.  They aren't referring to the gaps in the top and
>bottom of the frame lines, are they?  If so, these gaps seem to be the
>same width and, being outside the rangefinder patch, no double image
>will appear within them, of course.
>
>This has been puzzling me for quite some time; my grateful thanks for
>any answers.
>
>-Dave

Dave,

This was probably a late innovation.  I have both an M3 and an M2.  The M2
has the notches immediately above and below the rangefinder patch in the
viewfinder.  In fact, it is continuous with the patch.  The M2 serial # is
in the early 1,000,000.  However, the single stroke M3 I have does not have
the notches--ser- ial #922,xxx.  It must have been introduced sometime in
between the two.

Henry