I think you've got that wrong, Paul ... did you forget to square? The sensors in the K10D and K20D are both the same physical size, so a 400mm lens on each camera will cover the same angle of view.
If, instead, you fit a 300mm lens, and crop to the field of view of a 400mm lens, you'll end up with an image that's only got just over half as many pixels (3/4 x 3/4 = 9/16) - 8.2 Megapixels from the central portion of the K20D sensor. Just cropping to the same number of pixels as in the K10D sensor gives you pretty much the effect of a 1.2x focal length multiplier. (OK WW - you can scream now :-) On Fri, Jun 27, 2008 at 09:43:07AM -0400, Paul Stenquist wrote: > If your crops were of the same dimension in pixels and the framing on > the bird was the same, the K20D and 300 would yield a slightly larger > print. > Paul > On Jun 27, 2008, at 9:15 AM, John Wittingham wrote: > > > Thanks for the responses, OK I think I need to re-word this > > altogether, Pentax K10D 10.2 Megapixels fitted with 400mm lens v's > > Pentax K20D 14.6 Megapixels fitted with 300mm lens, assuming both > > lenses produce excellent results, which combination would give the > > bigger print size from a crop at the center of the frame if yoy > > were for example shooting a distant bird at the same distance in > > each case? > > > > Regards, > > > > John > > ________________________________________ > > From: [EMAIL PROTECTED] [EMAIL PROTECTED] On Behalf Of J. > > C. O'Connell [EMAIL PROTECTED] > > Sent: 27 June 2008 13:18 > > To: 'Pentax-Discuss Mail List' > > Subject: RE: Sensor resolution V focal length.......... > > > > Are you trying to say that there will be no resolution loss in > > using a K20D > > with a shorter lens vs a K10D with a longer lens if the AOV of the > > image > > is kept the same via cropping the K20D image? The REAL sensor size > > of the 2 > > cameras > > are NOT EQUIVALENT if you crop the K20D image and use a shorter fl > > lens. > > > > JC OCONNELL > > [EMAIL PROTECTED] > > > > > > -----Original Message----- > > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On > > Behalf Of > > Anthony Farr > > Sent: Friday, June 27, 2008 8:03 AM > > To: 'Pentax-Discuss Mail List' > > Subject: RE: Sensor resolution V focal length.......... > > > > > > The crop will be the same from K10d to K20d, because the crop > > factor is > > related to the sensor dimension not its resolution, and the two > > cameras have > > equivalent sensor dimensions. > > > > The K20D shots will "enlarge" more at 100% view, simply because it > > has a > > greater pixel density. This doesn't mean anything other than that > > your > > monitor resolution (e.g. 1024 x 768)represents a smaller patch of > > the K20ds > > sensor compared to the K10d. The >>whole<< picture will have the > > same field > > of view for the same lens when the two camera models are compared. > > You > > wouldn't print at 100%, the only practical use for this view is when > > performing some editing functions, and for pixel peeping. > > > > Regards, > > Anthony Farr > > > >> -----Original Message----- > >> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf > >> Of John Wittingham > >> Sent: Friday, 27 June 2008 8:59 PM > >> To: [email protected] > >> Subject: Sensor resolution V focal length.......... > >> > >> I'm in need of some longer glass, longer than 300mm. It occured to me > >> the > > other > >> day that the crop of a given area of a frame would be consirerably > >> bigger > > the more > >> resolution you have from the sensor of the camera viewed at 100%. So > >> I'm > > thinking > >> 400mm on the K10D would be approximately 33% bigger at the same crop > >> as it would be from 300mm viewed at 100% right? > >> > >> So if I'm using a K20D how much bigger would a crop of the same > >> subject > > shot with > >> the K10D be viewed at 100%, could I substitute pixels for focal > >> length > > providing the > >> lens resolution is up to the job? Are there any downsides other than > >> the > > obvious > >> differences when using a shorter focal length such as DoF? > >> > >> Regards, > >> > >> John > >> > >> -- > >> PDML Pentax-Discuss Mail List > >> [email protected] > >> 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 > > [email protected] > > 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 > > [email protected] > > 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 > > [email protected] > > 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 > [email protected] > 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 [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
