Archived posting to the Leica Users Group, 2007/01/16
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Understood, George. Those examples shot at mid apertures. I revisited my archive and found some examples on Velvia100F that were underexposed so that the sky was rendered as a very deep blue. In those the effect is much more pronounced. Some of my discussion with Len on this came from my interpretation of vignette as a mechanical vignette, for example from a too small hood. We were evidently discussing an optical effect. I was calling it fall off. Marty has somewhat confused me by quoting MTF figures(?) for the sagittal rays from the Leica specs. I tended to think of the MTF figures as resolution measures, but of course contrast is integral to that. There is a discussion on the prevalence of this (esp in wides) in Erwin Puts' lens compendium. The maths made my brain hurt! As a practical matter, I note that it can manifest most obviously in clear sky. In some of my shots it is only visible in one direction (ie one corner). Yet it is not always present and I cannot observe any effect in the lower (foreground) corners. My scan process and tonal adjustment in Photoshop both seem to exacerbate the effect. Also my choice of the Velvia100F in bright contrasty light through a lens with high resolution and contrast performance was never going to produce flat subtle images! I do so love this lens, though. I still have vague half formed theories in my head that the phenomenon is related to the blue end of the spectrum at the largest angles. Maybe someone can post some equivalent shots from other 28s a 24 or 21 or also from the Zeiss designs. I'm searching my chaotic archives as I have previously shot with the Contax G (Kyocera) 2.8 28 and also the Nikkor 2 28 on old slrs. As Marty has noted the effect is easily ameliorated by the lens distortion function in PS CS2. I found that the dodge tone functions in Photokit also work very well. Still, like you, I often burn in the corners (in homage to the Ansel concept for prints). Cheers Hoppy -----Original Message----- From: lug-bounces+hoppyman=bigpond.net.au@leica-users.org [mailto:lug-bounces+hoppyman=bigpond.net.au@leica-users.org] On Behalf Of Lottermoser George Sent: Wednesday, 17 January 2007 02:25 To: Leica Users Group Subject: Re: [Leica] 28 vignette I certainly observe fairly severe vignette in my recently acquired 28 summicron. Certainly more than the 28 elmarit. And more than your samples display. I don't mind the effect in many personal situations as I tend to burn corners a bit anyway. However, when I first saw it I immediately thought that I should start looking for a "center" filter. Regards, George Lottermoser george@imagist.com On Jan 15, 2007, at 5:19 PM, G Hopkinson wrote: > <http://gallery.leica-users.org/v/gh/a/Tas/Ta11.jpg.html> > <http://gallery.leica-users.org/v/gh/a/Tas/PA8.jpg.html> _______________________________________________ Leica Users Group. See http://leica-users.org/mailman/listinfo/lug for more information