OK, Peter, it seems the general consensus is that, as you say, DoF is affected only by focal length. (manufacturing variations notwithstanding). Found a Google discussion on the lens to film distance effect on DoF.
Jack --- On Fri, 9/12/08, P. J. Alling <[EMAIL PROTECTED]> wrote: > From: P. J. Alling <[EMAIL PROTECTED]> > Subject: Re: panasonic's new micro four/thirds camera: G1 > To: "Pentax-Discuss Mail List" <pdml@pdml.net> > Date: Friday, September 12, 2008, 12:51 PM > Jack Davis wrote: > > A closer proximity of lens and "film" would > produce a sharper image..however imperceptible, but your > answer is what I would guess in the case with pixels. > > I would think, however, that the same DOF might be > possible with a somewhat larger aperture and diffraction > reduced accordingly.(?) > > > I don't see why the second point would be true, the > focal length would > be the same so the actual aperture would be the same size. > You might be > right about the sharpness, but I would think lens > characteristics would > be more important than the airspace between the objective > and the > "sensor". One of the sharpest lenses I own is > the 4 inch, (100mm), 5 > element 4 group f3.5 Kodak Ektar on my Medalist II,, (6x9 > on 120 film), > it's relatively simple geometry means that theres a lot > of airspace > between it and the film, at least 6 times the distance as > the equivelent > 35mm lens, (Pentax 43mm limited), yet it's performance > is similar, in > fact it's actually quite a bit better wide open. > (I'd post a sample but > I don't have a medium format capable scanner set up > right now). > > Thanks, Peter! > > > > Final thoughts on the issue, > > > > Jack > > > > > > --- On Fri, 9/12/08, P. J. Alling > <[EMAIL PROTECTED]> wrote: > > > > > >> From: P. J. Alling > <[EMAIL PROTECTED]> > >> Subject: Re: panasonic's new micro four/thirds > camera: G1 > >> To: "Pentax-Discuss Mail List" > <pdml@pdml.net> > >> Date: Friday, September 12, 2008, 10:17 AM > >> Jack Davis wrote: > >> > >>> Will the fact that the sensor is closer to the > lens > >>> > >> produce a "sharper" image? > >> > >>> > >>> > >> Probably not. > >> > >>> Will the image circle of existing 4:3 lenses > not > >>> > >> completely cover the sensor, therefore, producing > >> vignetting, but increasing the telescopic effect? > >> > >>> Do to a gain in DOF, will small aperture > diffraction > >>> > >> be reduced? > >> > >>> > >>> > >> No more than on current 4:3 cameras. > >> > >>> Please be gentle. ;) > >>> > >>> > >> Suffer. > >> > >>> Jack > >>> > >>> > >>> > >>> --- On Fri, 9/12/08, P. J. Alling > >>> > >> <[EMAIL PROTECTED]> wrote: > >> > >>> > >>> > >>>> From: P. J. Alling > >>>> > >> <[EMAIL PROTECTED]> > >> > >>>> Subject: Re: panasonic's new micro > four/thirds > >>>> > >> camera: G1 > >> > >>>> To: "Pentax-Discuss Mail List" > >>>> > >> <pdml@pdml.net> > >> > >>>> Date: Friday, September 12, 2008, 9:45 AM > >>>> They're still hobbled by the small > sensor > >>>> > >> size. As > >> > >>>> technology improves > >>>> and 24x36mm sensors become more prevalent, > (and > >>>> > >> there's > >> > >>>> no upgrade path > >>>> even possible), I think this will be > relegated to > >>>> > >> a second > >> > >>>> class system, > >>>> sort of where 4:3 is headed today. The > same issue > >>>> > >> that > >> > >>>> always comes up > >>>> when comparing formats, bigger is better, > (higher > >>>> > >> image > >> > >>>> quality), if you > >>>> can afford it. > >>>> > >>>> Mike Johnson had an interesting take on > lens > >>>> > >> compactness. > >> > >>>> He always > >>>> thought that amateurs liked telephotos for > their > >>>> > >> extra > >> > >>>> reach, smaller > >>>> formats make for smaller long lenses with > the same > >>>> > >> reach, > >> > >>>> so that would > >>>> be good. But it's not the effective > focal > >>>> > >> length > >> > >>>> it's the physical > >>>> size that matters. Most amateurs want big > lenses > >>>> > >> because > >> > >>>> they look more > >>>> impressive. My 400 captures the same > image, (on > >>>> > >> my > >> > >>>> sensor), as your 800 > >>>> on your's, but the 800 trumps. > >>>> > >>>> In other words size /still/ matters. > >>>> > >>>> Subash wrote: > >>>> > >>>> > >>>>> since no one seems to have posted the > link > >>>>> > >> here... :-) > >> > >>>>> > http://www.dpreview.com/Previews/PanasonicG1/ > >>>>> > >>>>> > >>>>> > >>>>> > >>>> -- > >>>> You get further with a kind word and a > gun, than > >>>> > >> with a > >> > >>>> kind word alone. > >>>> --Al Capone. > >>>> > >>>> > >>>> -- > >>>> PDML Pentax-Discuss Mail List > >>>> PDML@pdml.net > >>>> > http://pdml.net/mailman/listinfo/pdml_pdml.net > >>>> to UNSUBSCRIBE from the PDML, please visit > the > >>>> > >> link > >> > >>>> directly above and follow the directions. > >>>> > >>>> > >>> > >>> > >>> > >>> > >> -- > >> You get further with a kind word and a gun, than > with a > >> kind word alone. > >> --Al Capone. > >> > >> > >> -- > >> PDML Pentax-Discuss Mail List > >> PDML@pdml.net > >> http://pdml.net/mailman/listinfo/pdml_pdml.net > >> to UNSUBSCRIBE from the PDML, please visit the > link > >> directly above and follow the directions. > >> > > > > > > > > > > > > > -- > You get further with a kind word and a gun, than with a > kind word alone. > --Al Capone. > > > -- > PDML Pentax-Discuss Mail List > PDML@pdml.net > http://pdml.net/mailman/listinfo/pdml_pdml.net > to UNSUBSCRIBE from the PDML, please visit the link > directly above and follow the directions. -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
