Re: [Leica] perforations

["Alan Hull" <hull@vaggeryd.mail.telia.com>]

Paul=20
Thanks for the rational analysis of my somewhat vague idea.  You have
obviously thought this through before, and better, than I did. =20

I am, however surprised that you think the lenses would have to be
recomputed.  Surely the tolerances are not that tight.  Maybe there will =
be
light falloff on only one corner and a different corner for different
lenses and bodies.  Either way, it kinda kills the idea.  Pity really.

Alan Hull

- ----------
> Fr=E5n: Paul and Paula Butzi=20

=20
> Assuming you wanted an aspect ratio of 4:5 (aka 1.25:1 or 8:10) and not
> lengthen the frame, you'd get an image area of 28.8x36mm instead of
> the current 35mm frame of 24x36mm.  Since the film base is actually
> 35mm wide, you'd have borders of 3.1mm on each edge, which is
> more than enough to allow loading and development in a reel, which
> I assume you'd want to be able to do.  You could get a bigger image
> by using longer frames and narrower borders, but not by much.
>=20
> Going from 24mm to 28.8 is a factor of 1.2 or 20% change in the
> magnification needed to produce an image of a given size.  An
> 8x10 from the new size would be an enlargement factor of 7
> instead of the factor of 8.46 for a 35mm negative with the end
> cropped off to make it an 8x10.  An 8.46x enlargement from the
> new negative would be 9.6 inches by 12.  A 7x enlargement from
> a current 35mm negative is 6.6x9.9.
>=20
> The image circle that the lenses would have to cover
> would go from 43.2mm to 46.1.  Since lenses for 35mm typically
> allow no movements, the designers usually arrange for the smallest
> image circle that will cover the negative (or slightly smaller for
> the Noctilux wide open :-).  Unless you wanted to lose 1.4mm off
> each corner, you'd need new lenses.  If you wanted to retain
> the familar 'focal length feel' you'd need new lenses recomputed
> for a focal length increase of 1.06.
>=20
> All your printing equipment would need to change.  My Schneider
> APO-Componon 40mm f/4 lens actually covers far in excess of 46.1mm
> so I'd not need a new enlarging lens, but I suspect that others might
> run into falloff.  Certainly all automated printing equipment would hav=
e
to
> be replaced.
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> It might be interesting to see if slide projectors would manage without
> new lenses, rather like super-slides.
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> All of this assumes that you actually want an image with an
> aspect ratio of 1.25:1 instead of 1.5:1.  I kind of like the
> longer aspect ratio.
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> Somehow I just can't see all that happening just for a 20% increase
> in image size.  It would have been a good decision at the outset,
> but it's too late now.
>=20
> I'd rather see an M6 with a quieter shutter.  I don't give a rip about
> flash sync or top speed, but I'd like them to cut the vibration as
> much as humanly possible to allow better shooting at very low
> shutter speeds.  I wouldn't mind shutter speeds in increments=20
> of 1/3 stop, either.  I'm undecided about more sophisticated metering
> and aperture priority auto-exposure. =20
>=20
> But I'd sure like less noise and less vibration.  Yes, I know the M6
> is quiet and low-vibration.  I'm greedy.
>=20
> -Paul
>=20
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