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 >> >>> --- >> >>> 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 >> >>> >> >>> >> >> --- >> >> 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 >> >> >> >> >> > --- >> > 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 >> > >> > >> --- >> 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 >> >> > --- > 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 > > --- 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