On Dec 15, 2009, at 1:11 PM, John Francis wrote: > On Tue, Dec 15, 2009 at 11:19:24AM -0500, John Sessoms wrote: >>>> May not have anything to do with it, but are you sure the diopter is >>>> set > correctly? >> >>> >>> That's not how the diopter correction works. >>> >>> There's nothing you can do with the adjustment to make an out-of-focus >>> image on the focussing screen appear sharp. >>> >> >> My understanding of how he described the problem he had a sharp image >> through the viewfinder when focusing manually, but the focus in the >> captured image wasn't where it was in the viewfinder. >> >> That describes the problem I experienced with the diopter. > > Well, in the world where the laws of physics and optics apply, that > is nothing to do with the diopter. If there is a sharp image on the > focussing screen, but not at the same point as on the film/sensor plane, > that's caused by a problem with the placement of the focussing screen. > > All the diopter does is to make it easier for your eyes to focus on the > image on the viewfinder screen. A poorly adjusted diopter can make it > impossible for you to see *anything* in focus, but it can't make part > of the image on the focussing screen appear sharper than it really is. > Obviously correct. When adjusting my diopter, I ignore the viewfinder image and concentrate on the sharpness of the lines on the focus screen. As you said, the diopter's only purpose is to focus the image of the screen. If the view through the lens is out of focus, a correctly adjusted diopter will provide a view of teh out of focus image, but any markings on the focus screen will be sharp. Paul > > -- > 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.
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