Re: Bokeh in 3d

[Richard Rylander <rlrylander@xxxxxxx>]

Joel Alpers wrote:

> Note: This from Greg Erker. We've been having trouble with
> his postings to this list bouncing for some reason...
>
> Hi all,
>
> ...
>   Quite interesting. Has anyone else experienced
> good or bad bokeh in 3d photos (MF, 35mm or other)?
>
> Greg

I very recently (last week) bought one of the new Voigtlander Bessa-L
cameras with a 15mm/F4.5 Heliar lens and tried some slide-bar stereo
shots.  The lens is incredible - 110 degree field of view
(corner-to-corner), no detectable distortion, crisp (even in the corners
of 11x14" prints, though the extreme corners of the full film frame are
a little soft), and amazing depth of field.  The lens will focus as
close as 0.3m.

It takes some doing to produce out-of-focus images, but the combination
of infinity focus and extremely close subject (or vice versa) will do
it.  The "out-of-focus" elements near the center of the frame are very
pleasing,  just a loss of detail (like the real world without my
glasses), but those in the corners of the frame show a very anisotropic
blurring (inevitable with an extreme wide angle).  The corner blurring
is not necessarily unpleasant, contributing to a sense of depth (even in
"monoscopic" prints) by "directing" your vision toward the center of the
frame.

The good bokeh in the center of the frame is due (I feel) mainly to an
aperture with 10 blades.  Out-of-focus highlights tend to take on the
shape of the aperture and in this case it is nearly circular (the reason
many Leica lenses are highly praised for their bokeh).  Corner
highlights for this extreme wide angle are elliptical, which is (as I
said) not unpleasant, but subconciously reminds you that you are viewing
a photograph - breaking the "real world" illusion stereo scenes normally
have.

This is only a problem using the 15mm Heliar in extreme situations.
Normally (focusing at the hyperfocal distance), the depth of field is
far, far more than adequate to sharply render everything from a couple
feet to infinity.