Archived posting to the Leica Users Group, 2004/10/01
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]The actual angle of incidence varies for each lens and is always a cone of rays not a single ray, at wide apertures and short focal lengths it is a pretty big cone too. At what pixel density the effect is negligible I have never seen discussed, it probably means any low pass filter in front of the sensor can never be optimised for a wide range of lenses. If the sensor site wells are not very deep and there is no filter perhaps it is within acceptable tolerance for most lenses. Real published data would help quieten the speculation. >From a geometrical point of view the idea that all retrofocus lenses are OK and that other short focal length lenses are not seems to be a considerable over simplification. It is certainly the case that any correcting prisms could only correct for one angle, at all others they would to an extent be worse - at what point this becomes negligible needs real data to evaluate. Frank --- simonogilvie@totalise.co.uk wrote: > Frank Dernie wrote: > > surely there's the rub, if there is a prism there > suitable for the 15 > > it will distort the rays from longer lenses, etc.. > > > On 30 Sep, 2004, at 20:30, JCB wrote: > >> Under the glass is a low pass filter and possibly > a ray bending prism > >> glass so that you may use a leica 15mm lens and > get a reasonable image > >> out to the edge. > > Being retrofocus designs the R wide lenses won't > need any ray-bending > at the sensor surely? Isn't that only required for > the M lenses that > protrude into the body? > > Simon. > > > ---- Message sent via Totalise Webmail - > http://www.totalise.co.uk/ > _______________________________________________ > Leica Users Group. > See http://leica-users.org/mailman/listinfo/lug for > more information >