Archived posting to the Leica Users Group, 2005/03/18
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]----- Original Message ----- From: "animal" <s.jessurun95@chello.nl> To: "Henning Wulff" <henningw@archiphoto.com> Sent: Friday, March 18, 2005 10:09 AM Subject: Re: [Leica] Digital cameras with large aperture lenses > > >> At 12:10 AM +0100 3/18/05, animal wrote: >>>>It might be 'twice as bright' but the sensor doesn't know that, and >>>>won't get the benefit. >>>> >>>>Erwin might indeed have some problems on digital fora unless he gets his >>>>technical stuff straight, as he seldom wins people over with his wit and >>>>humour on the net, although he apparently does have some in person. :-) >>>> >>>i find him a bit sarcastic. >>>just believe that if Leica has him as a tester or consultant that he must >>>know his stuff. >>>And very much doubt that his stuff is not straight(is that english?) >>>best regards >>>simon >> >> Hi Simon, >> >> Erwin definitely knows a lot of stuff, and many of his analyses are >> thorough and spot on, but he, like many other people including all >> present, doesn't know it all. There are many on this list who know more >> than him in various technical fields, let alone other fields, but he >> sometimes seems to forget that or not be able to admit it. >> >> This insistence on clinging to obviously indefensible points of view >> detracts from his many other accomplishments, and rubs many people the >> wrong way. His usage of English, admittedly not his best language, also >> makes him sound rather stuffy and pompous, which doesn't help. >> >> Tom Abrahamsson, who is a good friend of mine here in Vancouver, knows >> Erwin fairly well and says he has a good sense of humour and is fun to >> chat with over a drink or two. Unfortunately that persona hasn't shown up >> on the web. >> >> I certainly respect Erwin, and have had a couple of conversations with >> him over the years. I'd hoped to meet him last Photokina, but he didn't >> show up. He wound up with a bottle of Calvados that I sent his way with >> Tom and Tuulikki Abrahamsson, and he said he enjoyed that! I'd certainly >> like to sit down with him some time and discuss optics, which has always >> been an interest of mine and which I have studied some while getting some >> Physics degrees. >> >> In any case, as far as digital sensors go, very large aperture lenses of >> relatively short focal lengths do have an issue with using all of their >> light. It's the same issue as that of vignetting with wideangle lenses, >> ie, a lot of the light strikes the sensor at fairly large angle from the >> perpendicular, and the sensors can't make full use of that. >> >> At the moment it's just part of sensor technology, and affects all >> cameras to some degree or other, and can only be mitigated at this time >> by designing lenses optimized for digital use by having their rear nodal >> points at a very large distance from the sensor. This approaches the >> ideal, the so-called telecentric lenses. >> >> All the best, >> >> Henning >> >> -- >> * Henning J. Wulff >> /|\ Architect >> /###\ mailto:henningw@archiphoto.com >> |[ ]| http://www.archiphoto.com > > > Then i cannot understand the combination of 0.75 aperture lenses on > sensors. > For xray astronomy and remote sensing. > Nice coincidence i started with Physics as well. > best,simon >