[rollei_list] Re: DOF (was Re: Rolleiflex 35mm Cameras)

  • From: Eric Goldstein <egoldste@xxxxxxxxx>
  • To: rollei_list@xxxxxxxxxxxxx
  • Date: Fri, 13 Nov 2009 09:30:58 -0500

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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