JCO is correct. Paul On Apr 28, 2007, at 11:02 AM, J. C. O'Connell wrote: > Secondly, whether hes making a scientific statement > or dogmatic whatever, or just generalizing, its > still WRONG, because the DOF isnt kept same OR similar > by changing focal lengths if you keep the same camara > postion, it **changes*** with focal length if you > do that. > > jco > > -----Original Message----- > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On > Behalf Of > Tom C > Sent: Saturday, April 28, 2007 10:43 AM > To: [email protected] > Subject: RE: M85mm f2.0 bokeh > > > Certainly what you state regarding DOF is true. I believe though the > writer > was not making a dogmatic absolute statement of scientific fact. > He was > > generalizing. > >> As the camera: subject/background ratio wasn't altered, DOF should be >> SIMILAR for all four lenses. > > I'm pretty sure he knows that actual DOF is not changed by altering > the > subjects distance from the focal plane. That's only moving > subjects in > to, > out of, or within the range referred to as DOF. I think he means that > the > *perceived* DOF will be *similar*, which is true for lenses close > to the > > same focal length used at close to the same aperture. Not the same, > but > similar. > > Tom C. > > >> From: >Reply-To: Pentax-Discuss Mail List <[email protected]> >> To: "'Pentax-Discuss Mail List'" <[email protected]> >> Subject: RE: M85mm f2.0 bokeh >> Date: Sat, 28 Apr 2007 10:26:25 -0400 >> >> No,this assumption is wrong, DOF is >> constant only for same fstop and >> MAGIFICATION (in camera ). If he >> used same camera position and fstop >> and only changed lenses, the shorter >> lenses will have same perspective >> in the shots but with MORE Depth >> of field than the longer lenses. >> DOF is a function of magnification, >> NOT the "subject/background" ratio. > > Mr. J. > >>> >> -----Original Message----- >> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On >> Behalf Of > >> William Robb >> Sent: Saturday, April 28, 2007 9:10 AM >> To: Pentax-Discuss Mail List >> Subject: Re: M85mm f2.0 bokeh >> >> >> >> ----- Original Message ----- >> From: "Paul Stenquist" >> Subject: Re: M85mm f2.0 bokeh >> >> >>> Of course the 70 gives you more DOF. Thus, a bit crisper. >> >> I left the camera position static and cropped the 70mm and 77mm >> images >> to be similar to the 85mm images. >> As the camera: subject/background ratio wasn't altered, DOF should be >> similar for all four lenses. >> >> William Robb > > > > -- > PDML Pentax-Discuss Mail List > [email protected] > http://pdml.net/mailman/listinfo/pdml_pdml.net > > > -- > PDML Pentax-Discuss Mail List > [email protected] > http://pdml.net/mailman/listinfo/pdml_pdml.net
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