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From: Philip Webb <purslow@ca.inter.net>
To: gentoo-user@lists.gentoo.org
Subject: Re: [gentoo-user] merging or fitting images together
Date: Sun, 20 May 2012 02:45:30 -0400	[thread overview]
Message-ID: <20120520064530.GB3019@ca.inter.net> (raw)
In-Reply-To: <4613CE50-114F-4B8D-BBC1-188F6D30BC21@stellar.eclipse.co.uk>

120520 Stroller wrote:
> Zoom lenses were much less common even 2 or 3 decades ago.
> For a long time, a 50mm prime was the common kit lens,
> rather than the 18-105mm zoom which is sold today.
> This was because on a camera using 35mm film, a 50mm focal length
> gives a field of view very close to that seen naturally by the human eye. 
> Wikipedia states that "the first modern film zoom lens was designed c 1950
> by Roger Cuvillier" and Canon's official website (the "Canon Camera Museum")
> states that "The history of Canon's zoom lens goes back to 1954."
> Since the photos are stated go have been taken in 1953
> it seems highly unlikely that the photographer was using
> a highly expensive and cutting-edge zoom lens. I doubt many people
> would have been able to afford these zoom lenses when first released. 
> It seems to me safer to assume that the lens is a 50mm.

In fact, looking more closely at the picture of a ZI
which I've put up in my I/net 'test' dir (found on the I/net earlier),
it says 'F = 7,5 cm', so the lens appears to have been a  75 mm .

> I guess focal length may change fractionally during focussing
> -- as lenses are moved back and forth during as the focus ring is turned --
> however it may also be that a camera manufacturer designs a lens
> with a 48mm focal length because that's easier to construct for some reason
> or produces better images and decides to sell it as 50mm
> because a 2mm difference makes no difference to the photographer. 
> Or it may be that the distortion is caused by lens distortion
> perhaps Hugin is trying to compensate for that, and straightening up lines. 
> In any case, I might try re-doing the stitch a few times,
> each time telling Hugin the lens is 47mm, 48mm, 49mm, … 51mm, … 53mm.
> Perhaps you may find that one of those is perfectly spot on.

Thanks for the further lesson ! -- it sb tried at  75 mm .

-- 
========================,,============================================
SUPPORT     ___________//___,   Philip Webb
ELECTRIC   /] [] [] [] [] []|   Cities Centre, University of Toronto
TRANSIT    `-O----------O---'   purslowatchassdotutorontodotca




  reply	other threads:[~2012-05-20  6:47 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-05-10 20:52 [gentoo-user] merging or fitting images together Philip Webb
2012-05-10 21:43 ` Alex Schuster
2012-05-10 21:52 ` Dale
2012-05-11 19:31   ` Philip Webb
2012-05-12  1:25     ` Dale
2012-05-12 13:22       ` Philip Webb
2012-05-12 19:13         ` Michael Mol
2012-05-15  2:50           ` Philip Webb
2012-05-15 23:29             ` Urs Schutz
2012-05-16  0:19               ` Philip Webb
2012-05-16  4:12                 ` Philip Webb
2012-05-16 23:11                   ` Urs Schutz
2012-05-17  1:27                     ` Philip Webb
2012-05-17  3:08             ` Michael Mol
2012-05-17  4:34               ` Philip Webb
2012-05-17  4:59                 ` Stroller
2012-05-17  6:19                   ` Pandu Poluan
2012-05-17  8:20                     ` Philip Webb
2012-05-19  3:49                 ` Michael Mol
2012-05-19  4:38                   ` Philip Webb
2012-05-19 19:28                     ` Michael Mol
2012-05-20  2:01                       ` Stroller
2012-05-20  6:45                         ` Philip Webb [this message]
2012-05-20 21:48                         ` Michael Mol
2012-05-21  0:33                           ` Philip Webb
2012-05-21  1:06                             ` Michael Mol
2012-05-21 16:09                               ` Stroller
2012-05-21 16:31                                 ` Michael Mol
2012-05-21 16:54                                   ` Michael Mol
2012-05-21 16:57                                   ` Paul Hartman
2012-05-21 17:16                                     ` Michael Mol
2012-05-20  6:33                       ` Philip Webb

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