Archived posting to the Leica Users Group, 2005/02/26
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Film is flat and equally sensitive to light regardless of the angle of incidence of the light impinging upon it. Digital sensors have light sensitive wells, anti-aliasing and colour filters over them, meaning that light hitting them at an angle is potentially reduced in strength at the peripheral photosites. Reflex lenses have had to have their exit pupils moved away from the film as part of the necessity to clear the reflex mirror. Lenses for viewfinder cameras, including rangefinders, do not have this constraint and so often have exit pupils much closer to the focal plane than lenses designed for film. This is one of the reasons why wide angles for rangefinders are usually superior to reflex equivalents on film - less compromise. The problem is that these WA lenses give very strong vignetting on the Epson, and, I presume, any digital sensor. Goodness knows how unsuitable a 36x24mm size sensor would be with lenses designed for rangefinders, The Epson is restricted enough, but the effect can be corrected in software within dynamic range constraints. Obviously therefore the effect is dependant on the design of the actual lens in question, not just focal length. The Voigtlander 12mm vignettes much less than the 15mm for example, and the 21mm Leica much less than the 21mm Voigtlander. The Epson is supplied with correction software for the Voigtlander lenses pre set, and a slider to correct others by eye. Hope this helps, Frank On 26 Feb, 2005, at 14:51, Christopher Driggett wrote: > Would some explain this vignetting problem or point me to a link? Why > does film not have this which is full frame and a digital sensor which > is roughly the 2/3 the size in the middle do? Why do I not have this > on my D2h and do on my Epson? > Thanks, > Chris > > On Feb 26, 2005, at 1:36 AM, Steve Unsworth wrote: > >> Nathan, I could be wrong, but I wonder if Leica were fixated on the >> idea >> of a full frame sensor for the digital M when they kept saying that it >> wasn't possible? From what I've seen of the vignetting in some of the >> shots from the RD1 they cold still be right. The decision to go for a >> 1.3 chip has probably made the engineer's lives much easier :-) >> >> Does anyone think that the non-professional SLR market will eventually >> stabilise at 10 mega pixels? If manufacturers continue to up the pixel >> count on the 1.6 crop SLRs won't we begin to see the same kind of >> noise >> that plagues the P&S market? >> >> Steve >> >> >> -----Original Message----- >> From: lug-bounces+mail=steveunsworth.co.uk@leica-users.org >> [mailto:lug-bounces+mail=steveunsworth.co.uk@leica-users.org] On >> Behalf >> Of Nathan Wajsman >> Sent: 26 February 2005 06:59 >> To: Leica Users Group >> Subject: Re: [Leica] LEICA could be clever >> >> I fully agree with you that the lenses you mention are fantastic, and >> I >> have bought several of them as well (although I have since sold some). >> However, most of these lenses were introduced in the 1990s. In the >> past >> few years, aside from the M7, Leica has introduced very few really new >> products. OK, there is the rebadged Panasonic, but otherwise we are >> talking mostly about new coverings of existing models, a retro MP and >> not much else. The DMR is a good idea but it is at least a year too >> late. And worst of all is the company's longtime insistence that a >> digital M was impossible for all kinds of technical reasons followed >> by >> the sudden reversal of that opinion after Epson/Cosina introduced the >> RD1. >> >> >> _______________________________________________ >> Leica Users Group. >> See http://leica-users.org/mailman/listinfo/lug for more information > > _______________________________________________ > Leica Users Group. > See http://leica-users.org/mailman/listinfo/lug for more information >