-----Original Message-----
From: rollei_list-bounce@xxxxxxxxxxxxx
[mailto:rollei_list-bounce@xxxxxxxxxxxxx]On Behalf Of CarlosMFreaza
Sent: Friday, November 13, 2009 10:35 AM
To: rollei_list@xxxxxxxxxxxxx
Subject: [rollei_list] Re: DOF (was Re: Rolleiflex 35mm Cameras)
And it is not _purely_ a function of aperture, if you think DOF as
percentage, this is a statement from one of the website you quoted:
"..depth of field, expressed as a percentage of the distance to the
subject (Total DOF/s %), is inversely proportional to focal
length. It
can be very small for long telephoto lenses..."
Carlos
2009/11/13, CarlosMFreaza <cmfreaza@xxxxxxxxx>:
I'd say that I learnt nothing Eric.
Carlos
2009/11/13, Eric Goldstein <egoldste@xxxxxxxxx>:
Hi Carlos -
Here is my original statement:
It can be argued that DOF is purely a function of aperture
and not FL.
I'm glad you were able to learn something useful from this
discussion.
Eric Goldstein
--
On Fri, Nov 13, 2009 at 9:24 AM, CarlosMFreaza
<cmfreaza@xxxxxxxxx> wrote:
Yes Eric; BTW, I interpret the last part of Richard
explanation: "All
this given for a constant distance from the subjects" that the
difference for the lenses focal length has been cancelled
changing the
focusing distance to the subject. It's very easy to find
the equal DOF
for two different lenses changing the lens FL parameter and the
Subject focusing distance parameter using a DOF calculator
keeping
identical the COC, frame size and aperture, this was the
confusing
part (to me) of your original statement because since I'm
changing the
focusing distance to equal the DOF for two different FL, I
could think
that the DOF is a subject focusing distance function.
Carlos
2009/11/13, Eric Goldstein <egoldste@xxxxxxxxx>:
Our Richard should be writing and teaching... he has the
knack for clarity.
Eric Goldstein
--
On Fri, Nov 13, 2009 at 7:59 AM, CarlosMFreaza
<cmfreaza@xxxxxxxxx> wrote:
Yes, I agree absolutely, if Richard explained DOF that
way from the
beginning, the point would be clear to me from the
beginning too, it's
a knowledge that you learn using DOF calculators and
cameras-lenses
DOF indicators.-
Carlos
2009/11/13 Eric Goldstein <egoldste@xxxxxxxxx>:
Yes. This was covered in the links I provided, but not
expressed so
simply and elegantly.
Eric Goldstein
--
On Fri, Nov 13, 2009 at 3:27 AM, Richard Knoppow
<dickburk@xxxxxxxxxxxxx> wrote:
----- Original Message ----- From: "Eric Goldstein"
<egoldste@xxxxxxxxx>
To: <rollei_list@xxxxxxxxxxxxx>
Sent: Tuesday, November 10, 2009 7:30 AM
Subject: [rollei_list] Re: Rolleiflex 35mm Cameras
It is. Another interesting discussion relative to
aperture, DOF and
perceived sharpness:
http://www.luminous-landscape.com/tutorials/dof2.shtml
Eric Goldstein
Depth of field/depth of focus can be defined as
either the amount of
defocusing that produces a constant size circle of
confusion or for a circle
of confusion which is a constant percentage of focal
length. When the first
definition is used the depth depends only on the
physical size of the
aperture. Thus it will be the same for a 100mm lens at
f/2.8 as for a 200mm
lens at f/5.6. Where the image from the shorter lens
is magnified to equal
the image from the larger lens the DOF will be
constant with f/stop. All
this given for a constant distance from the subjects.
--
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx
---
