Well - changing the aperture causes focus shift in all lenses but in good lenses this is negligible - we are talking of some 1/100 of millimeters - and this means that the focal length indeed changes and so the magnification changes, too. IMHO in practice you would need to have a really bad lens to even notice this. All the best! Raimo Personal photography homepage at http://personal.inet.fi/private/raimo.korhonen -----Alkuperäinen viesti----- Lähettäjä: Rob Studdert <[EMAIL PROTECTED]> Vastaanottaja: [EMAIL PROTECTED] <[EMAIL PROTECTED]> Päivä: 07. tammikuuta 2001 1:50 Aihe: Re: Bracketing Changes Image Size On 6 Jan 2001, at 14:48, Bill Johnson wrote: > Say, for example, that you are taking a photo with a > main subject placed at 2 meters from the camera, and a > background subject at 4 meters. You bracket exposures, > and find that you prefer f/2 for your main subject (at > 2 meters) and f/5.6 for your background subject (that > is at 4 meters). Now, assuming a normal to moderate > telephoto lens, the background subject will be out of > focus either way, but it will be *more* out of focus > at f/2. Now you would like to (in a photo editing > program) paste the f/5.6 background into the f/2 > photo, but it will not be quite the same size as inthe > f/2 photo. It will be slightly smaller. Does this > make sense to anyone else? I don't do much with > photo editing software, but this is how it seems to > me. > > Comments? Hi Bill, Yes the rendition of the elements of the image in front of and behind the plane of focus will be larger due to the larger circle of confusion but I would assume that the image at the plane of focus will not change magnification. Pure speculation but maybe this is what was being discussed? Cheers, Rob Studdert HURSTVILLE AUSTRALIA Tel +61-2-9554-4110 Fax +61-2-9554-9259 UTC(GMT) +10 Hours [EMAIL PROTECTED] http://www.ozemail.com.au/~distudio/publications.html This message is from the Pentax-Discuss Mail List. To unsubscribe, visit http://www.pdml.net and follow the directions. Don't forget to visit the PUG at http://pug.komkon.org This message is from the Pentax-Discuss Mail List. To unsubscribe, visit http://www.pdml.net and follow the directions. Don't forget to visit the PUG at http://pug.komkon.org
