On Apr 12, 2010, at 3:38 PM, J.C. O'Connell wrote:
High performance ultra wide zooms (UW) don’t really exist. Go with a
UW
prime
and even that wont match basic wide primes.
--
The DA 12-24/4 is reportedly comparable in performance to the DA
14/2.8, although it's a stop slower. I've also read that it's actually
better than the A 15/3.5 at comparable FOV. I haven't compared it
directly to either, but I know from experience that it's an excellent
lens, capable of generating a nice, crisp double page spread at 12mm.
Good tool.
Paul
J.C. O'Connell (mailto:hifis...@gate.net)
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-----Original Message-----
From: pdml-boun...@pdml.net [mailto:pdml-boun...@pdml.net] On Behalf
Of
David Parsons
Sent: Monday, April 12, 2010 3:12 PM
To: Pentax-Discuss Mail List
Subject: Re: Ultra-wide zooms
There are two common crops for dSLRs as compared to FF SLR, 1.5
(Nikon and
Pentax) and 1.6 (Canon).
Canon has a 1.3 crop on some of their pro bodies.
P&S sensors are a whole other barrel of fish and there are many
sizes, but
they don't correlate because the lenses are not interchangeable.
On Mon, Apr 12, 2010 at 3:00 PM, Keith Whaley <keit...@dslextreme.com>
wrote:
P N Stenquist wrote:
On Apr 12, 2010, at 8:48 AM, Keith Whaley wrote:
Bong Manayon wrote:
Thinking of ...
1. Pentax DA 12-24
2. Sigma 10-20
3. Tamron 10-24
Am not into fish-eyes so those options are out. Any votes for or
against any of those listed above? Thanks!
Bong
I don't think those focal lengths are 35mm-equivalent numbers. I
suspect they're double ~ such as the Pentax DA 12-24 is really like
a 35mm lens of 24-48mm focal length. Nice wide angle-to-normal
lens,
but hardly a fish-eye...
First, the conversion factor for angle of view is 1.5.
Was Bong talking about a specific camera? I know we were talking
digitals, but, I thought each camera had it's own conversion camera.
In my limited experience, which does NOT include DSLRs, most cameras
differ a little as to what their 35mm equivalent is. I avoid the
uncertainty by referring to the owner's manual for each camera. They
always mention it...
So the 12-24 has the same _angle of view_ on an APS-C DSLR as an
18-36 would have on a conventional 35 mm frame.
Cropping factor, or what I call the telephoto effect, brought on by
the size of the sensor. In other words, the ratio derives from how
much smaller the DSLR's sensor is compared to 35mm film size.
See:
http://www.minasi.com/photos/dslrmag/
However, the focal length is 12-24. That doesn't change, regardless
of the format. Furthermore, it's not a fisheye on any format. It's a
rectilinear lens. In other words, the optics make the verticals as
true as possible given the size of the elements and the constraints
of physical science. Paul
Quite so. Thanks Paul.
keith whaley
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