[rollei_list] Re: DOF (was Re: Rolleiflex 35mm Cameras)
- From: CarlosMFreaza <cmfreaza@xxxxxxxxx>
- To: rollei_list@xxxxxxxxxxxxx
- Date: Fri, 13 Nov 2009 13:01:22 -0300
Hi Austin:
It's a fact you and Eric did not explain the point
clearly, and since I was thinking on the DOF as percentage of the
distance to the subject, I was right. I always had a practical
knowledge on the point, it can be expressed differently, I finally got
it from your point of view, as I wrote, I suddenly noticed what you
were talking about, I "saw" your point, but I learnt nothing.
I'm not spending energy since I understand the point perfectly and
from different point of views.
Carlos
2009/11/13, Austin Franklin <austin.franklin@xxxxxxxxxxx>:
> Hi Carlos,
>
> You really are spending an awful lot of energy trying to convince someone,
> more so your self, that you weren't wrong. You were.
>
> Regards,
>
> Austin
>
> > -----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
> > > > >> >>> ---
> ---
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