[Leica] Optics question

[grduprey at mchsi.com (grduprey at mchsi.com)]

Jim,

It is a matter of cost, variable, slower max aperture lenses are much 
cheaper to design and produce, than faster fixed aperture lenses.

Gene


----- Original Message -----
From: Jim Shulman <jshul at comcast.net>
To: 'Leica Users Group' <lug at leica-users.org>
Sent: Thu, 24 Dec 2009 10:01:31 -0600 (CST)
Subject: [Leica] Optics question

Puzzled about something, which the group may be able to answer.

 

I've been looking at specs for some of the digital four-thirds cameras,
where the sensor size roughly corresponds to the frame of the old 16MM movie
equipment.  In fact, many are now adapting old 16mm cine lenses to these
cameras, and preserving the original focal length perspective of the lenses
(in that a 25mm lens is really a "normal" lens, and not a medium telephoto,
etc.)

 

My question is about zooms and aperture.  During the 1950s and 60s there
were a number of 16mm cine zoom lenses that preserved a constant aperture of
about f2 or 2.8 throughout a fairly wide range, 12mm-17mm wide angle (equal
to 24-34mm in 35mm photography) through 70-120mm telephoto (140mm -240mm
equivalent).  Yet on the new cameras the zooms attached are not nearly so
fast, and have varying apertures (sometimes at a tele equivalent of f5.6)

 

Any idea why lens manufacturers for this size can't (or won't) make a fast,
constant aperture zoom?  If this could be done, albeit with large lenses,
nearly 50 years ago, I don't see why it isn't done today.

 

Thanks,

Jim Shulman

Wynnewood, PA

 


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