[rollei_list] Re: Visualization/focal length aid?
- From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
- To: <rollei_list@xxxxxxxxxxxxx>
- Date: Sun, 4 May 2008 15:53:27 -0700
----- Original Message -----
From: "Thor Legvold" <tlegvold@xxxxxxx>
To: <rolleiusers@xxxxxxxxxxxxxxx>;
<rollei_list@xxxxxxxxxxxxx>; "Rollei Users"
<rollei-user@xxxxxxxxxxxxxxxxxxx>
Sent: Sunday, May 04, 2008 2:38 PM
Subject: [rollei_list] Visualization/focal length aid?
I remember reading some years about a way to practice
visualization and judging appropriate focal length.
Unfortunately, I haven't been able to find it anywhere on
the internet, and am sure someone here knows about it.
Basically, it involved using an empty slide mount, and a
thread or string attached to the mount. The string was
marked or knotted, but I don't remember exactly how
(every 5 or 10cm?). You could hold the lide mount up and
look through it, and when you get the composition you
want, by looking at the thread you can see what focal
length would give the same perspective.
Does anyone else know about this? Anyone use it, or
recommend it?
Cheers,
Thor
This is an old trick for framing and is the principle
of the wire frame finder found on press cameras. The viewing
angle of a frame of any size is the same as a lens of the
focal length of its diagonal when held at that distance from
the eye. For instance, a 4x5 frame will have the view of a
6" lens when held 6 inches from the eye. Of course, any size
frame can be used for any focal length by multiplying or
deviding its diagonal by the diagonal of the desired format.
That is, a 4x5 frame will work for 8x10 but the focal lengh
of the lens on the 8x10 camera will be twice the distance of
the frame from the eye for the given view. The frame would
also work for 35mm by deviding the distance by the correct
ratio.
So, if you want to find what focal length lens to use
for a given viewpoint make a frame of the right aspect ratio
for the format and of a convenient size and attach a
calibrated string to it. Move the frame back and forth until
it covers the view you want and then measure its distance
from your eye at that point with the string. This will tell
you what focal length lens to use.
Actually, you can make a frame of your hands as the old
time movie cameramen did and use it to find the approximate
focal length you need.
---
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx
To decide on what focal lengt
---
Rollei List
- Post to rollei_list@xxxxxxxxxxxxx
- Subscribe at rollei_list-request@xxxxxxxxxxxxx with 'subscribe'
in the subject field OR by logging into www.freelists.org
- Unsubscribe at rollei_list-request@xxxxxxxxxxxxx with
'unsubscribe' in the subject field OR by logging into www.freelists.org
- Online, searchable archives are available at
//www.freelists.org/archives/rollei_list
Other related posts:
