Archived posting to the Leica Users Group, 2010/11/14
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]I have not played around much with the coding but have not been that successful when I did. I quickly learned that, apart from having the "right" info in the EXIF file, just setting the same focal length as one of the Leica lenses is no guarantee of anything. On reflection it seems likely that the colour correction required is dependant on the position of the exit pupil of the lens (hence the angle of rays through the IR filter). This is entirely lens design dependant and the focal length is only part of it, the 12mm CV lens has an exit pupil -further- from the plane of focus than their 15mm lens, for example, so the 15 behaves like a shorter focal length than the 12 in this respect. The amount of vignetting correction is also design dependant, with symmetrical lenses having more inherent vignetting than retrofocus, but both varying in detail following the exact optical design. Anyway it seems to me unlikely for -any- of the Leica lens profiles to exactly match the requirements of 3rd party manufactured lenses. Cornerfix seems an altogether more practical solution if precise compensation is the goal... In my case the vignetting doesn't bother me as much as the colour shift because I am used to it anyway! cheers, FD On 13 Nov, 2010, at 17:54, Jean Louchet wrote: > Hi Vick (and all) > >> On 11/9/2010 3:52 AM, Jean Louchet wrote: >>> Just to share my short experience, on my recently acquired M9, the CV >>> 12mm does require vignetting correction. After some disappointment >>> with coding it as the 16/18/21 (code 010000) and several other tests, >>> I coded it with code 011001 (recognised as a 2.8/24 ASPH) and the >>> results now look not perfect but very acceptable. Has ayone found a >>> better suited code? >>> I am using the same code for the CV 15mm as well. >>> Jean >> >> Date: Tue, 9 Nov 2010 08:17:30 -0500 >> From: Vick Ko <vick.ko at sympatico.ca> >> >> Very informative, Jean >> Do you use the same code for the M8? >> What method are you using? Black marker? > > As the M8 only uses the centre of the image provided by the lenses, > the vignetting of the 12 mm and 15 mm are not very disturbing on the > M8; however, a code that works on the M9 will work on the M8. The M8 > will be less sensitive to using a (slightly) wrong code. > > I agree with other list members that vignetting is not really an issue > from 50mm up on the M9 (and its equivalent 35mm on the M8) and hardly > perceptible on a 35 (M9) or 28 (M8) but it is really worth coding the > lens to correct vignetting for shorter focal lengths. I have never > been annoyed by any colour shift on the M9 even on extreme > wide-angles. > > All my CV lenses are the old type, L39 mount so I have to use adapters > like the Voigtlander type II where metal has not been removed in front > of the code sensors (unlike the type I adapters and most original > Leica adapters). They are pre-engraved, so it is easy to mark them > using a thin black permanent marker. A cotton with alcohol will easily > remove the ink if willing to try another code. For both 12 and 15mm I > use a 35/135 adapter. I have a couple of older lenses (Minolta and > Leica) where I wrote directly on the mount, it works fine. > > My own experience on adapters: my preferred are the Voigtlanders type > II, I found the Millich are well done but don't get the lens properly > oriented, and the ones sold on ebay by ***sweden or ADPLO have a rough > mating surface and don't have the right orientation either. > > Oh yes, one last thing, the excellent site > http://whimster-photography.com/leica_m_lens_codes/index.html > has been updated a couple of days ago and now gives the codes of the > 1.4/21 and 1.4/24. I will try them with the CV12 and 15, and tell here > how it works. > > Jean > > _______________________________________________ > Leica Users Group. > See http://leica-users.org/mailman/listinfo/lug for more information