Archived posting to the Leica Users Group, 2007/01/07
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Don, Enough said. Time to move on. Jim Nichols Tullahoma, TN USA ----- Original Message ----- From: "Don Dory" <don.dory@gmail.com> To: "Leica Users Group" <lug@leica-users.org> Sent: Sunday, January 07, 2007 1:30 PM Subject: Re: [Leica] A tripod, an M8, and two candles - do some science > Jim, > The laws of physics do not change and light of different wave lengths > focuses at different points. Modern glasses help a lot in this especially > if properly balanced with anomalous dispersion glass. But, and this is a > big on, is that this only holds for a given set of wave lengths. Two > extreme examples would be a lens that could focus X-rays not being the hot > ticket for normal light and the lenses that are used in steppers. These > are > optimized for one frequency of light used to etch the lines on the chips. > Totally useless outside of a very narrow wavelength of light. > > Let's go back to Brian's and Steve's images. Brian used a Noctilux which > was a heavily compromised design to generate good imagery at F1 on film > without using aspheric elements. For the use it was intended it is a > masterpiece. It was never intended to do well with very long wavelengths > of > light. Moving on to Steve's images, they are much crisper and seem in > better focus. Probably due to a much more modern design that handles > longer > wavelengths with more panache. > > Last, to pull a Ted; geesh guys, get a life. The new sensor handles light > differently than we are used to. Non panchromatic films don't look the > same, neither does Ektachrome look like Kodachrome. For most applications > the M8 delivers an amazing wonderful image that is very sharp out of the > box > with out the built in sharpening from Nikon or the need to sharpen due to > an > aggressive anti-aliasing filter in Canon. > > Maybe I should buy three or four of these things and leave them in the box > to fund my retirement ala a two lug M5 NOS or a black paint SP. :) > > Don > don.dory@gmail.com > > On 1/7/07, Jim Nichols <jhnichols@bellsouth.net> wrote: >> >> Adam, >> >> I went back and reviewed the Noctilux data that Brian posted earlier >> today. >> There does not appear to be a separate "R" index on the Noctilux for use >> in >> infrared photography. I recall being told some time ago that the >> separate >> index was no longer needed on recent Leica lenses because the color >> correction has improved to the point that IR is rendered properly when >> using >> the normal focusing index. If this is true, then one should be able to >> focus properly using visible light, regardless of the nature of the light >> source. Maybe someone can elaborate on this. >> >> Jim Nichols >> Tullahoma, TN USA >> ----- Original Message ----- >> From: "Adam Bridge" <abridge@gmail.com> >> To: "Leica Users Group" <lug@leica-users.org> >> Sent: Sunday, January 07, 2007 12:32 PM >> Subject: Re: [Leica] A tripod, an M8, and two candles - do some science >> >> >> > If infra red is really a prime illuminate in the image then the focus >> > will be shifted because of the substantially longer wavelengths of the >> > IR. So you'd expect the focus to be "off" - if it weren't I'd be >> > thinking IR wasn't an issue. >> > >> > I'd like to see some rigorous science done here - creating a >> > thoughtful series of controlled experiments to explore what is being >> > observed and determine the meaning. >> > >> > Adam >> > >> > >> > On 1/7/07, Jim Nichols <jhnichols@bellsouth.net> wrote: >> >> Brian, >> >> >> >> I don't wish to get into the definition of depth of field or >> >> allowable >> >> circles of confusion. However, if you go to the full size image in >> >> the >> >> second photo, you will notice that the highlights on the rim of the >> neck >> >> of >> >> the oil candle are not nearly as sharp as the highlights on the frame >> in >> >> the >> >> background. This is what led me to state that the sharpest focus is >> >> behind >> >> the candle flame. >> >> >> >> Jim Nichols >> >> Tullahoma, TN USA >> >> ----- Original Message ----- >> >> From: "Brian Reid" <reid@mejac.palo-alto.ca.us> >> >> To: "Leica Users Group" <lug@leica-users.org> >> >> Sent: Sunday, January 07, 2007 11:49 AM >> >> Subject: Re: [Leica] A tripod, an M8, and two candles >> >> >> >> >> >> > >> >> >> I am assuming that you were careful not to change the focus between >> >> >> the >> >> >> two shots. >> >> > >> >> > Correct. >> >> > >> >> >> I notice in the second shot that the frame in the background seems >> to >> >> >> be >> >> >> the plane in focus. The IR effects are interesting, but I do not >> >> >> think >> >> >> that you have eliminated the focus question. >> >> > >> >> > According to the manual that came with the Noctilux, the depth of >> field >> >> > at >> >> > f/5.6 at that distance (1.5 meters) is about 22cm. I believe I have >> >> > eliminated the focus question. >> >> > >> >> > ( >> http://www.leica-camera.us/assets/file/download.php?filename=file_153.pdf, >> >> > page 6) >> >> > >> >> > >> >> > >> >> > _______________________________________________ >> >> > 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 >> >> >> > >> > _______________________________________________ >> > 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 >> > > _______________________________________________ > Leica Users Group. > See http://leica-users.org/mailman/listinfo/lug for more information >