OK, try this:
Draw two parallel lines on a piece of paper - one goes through the node of
the lens, the other the film plane. Draw a line at right angles connecting
them - the centre line of a normal lens. Don't worry about dimensions, they
are arbitrary.
The point where the lens centre line meets the nodal line is 'X'
Now fold a piece of paper to make an angle of say 45 degress, and use this
to draw a triangle with point at X and base on the film plane. Have the
angles equal either side of the lens centre line. Measure the length of the
base on the film plane.
Now take the same piece of paper, but swing it round so that one edge is
along the lens centre line. Draw the resulting triangle. Measure the
resulting length of the base on the film plane. Is it longer? Has the
actual angle of view changed (you used the same folded piece of paper, did
you not)? Has the apparent angle of view changed?
Piers
-----Original Message-----
From: owner-olympus@xxxxxxxxxxxxxxx [mailto:owner-olympus@xxxxxxxxxxxxxxx]
On Behalf Of Geilfuss Charles
Sent: 13 October 2003 20:04
To: 'olympus@xxxxxxxxxxxxxxx'
Subject: Re: [OM] Re: 35 Shift
Well Piers, now that you have completely confused me, it only confirms what
I DO know about the 35 Shift...I WANT one.
Charlie
-----Original Message-----
From: Piers Hemy [mailto:piers@xxxxxxxx]
Sent: Monday, October 13, 2003 2:59 PM
To: olympus@xxxxxxxxxxxxxxx
Subject: Re: [OM] Re: 35 Shift
This has come up before, and I didn't believe the answer offered then. But
it has taken me awhile to work out why...
It's my understanding that the 83 degrees coverage is *not* the image
circle, but the field of view when the len is at maximum shift.
It isn't that the shift lens itself can defy the laws of optical physics,
but that when the lens is shifted, the field of view is no longer
perpendicular to the lens axis and perpendicular to the film plane (but
still parallel to the film plane). Therefore, the greater the amount of
shift, the smaller the angle between the lensaxis and film plane, and the
greater the angle of view.
It's the laws of trigonometry.
Piers
-----Original Message-----
From: owner-olympus@xxxxxxxxxxxxxxx [mailto:owner-olympus@xxxxxxxxxxxxxxx]
On Behalf Of Geilfuss Charles
Sent: 13 October 2003 19:19
To: 'olympus@xxxxxxxxxxxxxxx'
Subject: Re: [OM] Re: 35 Shift
Thanks for clarifying my misinformation Walt. I guess those Laws of Optical
Physics can only be bent not broken.
Charlie
-----Original Message-----
From: Walt Wayman [mailto:hiwayman@xxxxxxxxx]
Sent: Monday, October 13, 2003 2:12 PM
To: olympus@xxxxxxxxxxxxxxx
Subject: Re: [OM] Re: 35 Shift
Those numbers, while not intentionally misleading, are still often
misleading. The "field of view" of the 35mm shift is 83 degrees, but that
refers to the image circle around which you may wander in shifting the lens
while composing the final shot, which will cover -- anyone? anyone? -- yes,
63 degrees, like a normal 35mm lens.
Just to be sure, I have, moments before writing this, compared the field of
view of a 35 shift with a 35/2. They are identical.
Walt _____________________________________________________________
"Patriotism means being loyal to your country all the time
and to its government when it deserves it." -- Mark Twain
---------- Original Message ----------------------------------
From: Geilfuss Charles <Charles.Geilfuss@xxxxxxxxxxxxxxxxx>
Reply-To: olympus@xxxxxxxxxxxxxxx
Date: Mon, 13 Oct 2003 12:59:59 -0500
>Greetings Peter,
>Sounds like a great trip and I look forward to seeing some of your
>scanned images. Regarding the 35 Shift: mind you I've never actually
>used one of these lenses, but according to the Unofficial OM Sales Info
>File, the 35 Shift has a practical field of view of 83 degrees which is
>more akin to a 24mm lens instead of the usual 63 degree field of view
>of a typical 35mm lens. You may find it more to your satisfaction than
>you realise. Another plus, it's about one third the cost of the rare
>and lofty 24 Shift.
>
>Charlie Geilfuss
>
< This message was delivered via the Olympus Mailing List >
< For questions, mailto:owner-olympus@xxxxxxxxxxxxxxx >
< Web Page: http://Zuiko.sls.bc.ca/swright/olympuslist.html >
< This message was delivered via the Olympus Mailing List >
< For questions, mailto:owner-olympus@xxxxxxxxxxxxxxx >
< Web Page: http://Zuiko.sls.bc.ca/swright/olympuslist.html >
< This message was delivered via the Olympus Mailing List >
< For questions, mailto:owner-olympus@xxxxxxxxxxxxxxx >
< Web Page: http://Zuiko.sls.bc.ca/swright/olympuslist.html >
< This message was delivered via the Olympus Mailing List >
< For questions, mailto:owner-olympus@xxxxxxxxxxxxxxx >
< Web Page: http://Zuiko.sls.bc.ca/swright/olympuslist.html >
< This message was delivered via the Olympus Mailing List >
< For questions, mailto:owner-olympus@xxxxxxxxxxxxxxx >
< Web Page: http://Zuiko.sls.bc.ca/swright/olympuslist.html >
|