Archived posting to the Leica Users Group, 2010/11/15
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]my completely unscientific observations: the CV 12 & 15 seem to show less of the infrared color shift than leica lenses--need less filtration ric On Nov 15, 2010, at 1:38 AM, Frank Dernie wrote: > 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 > > _______________________________________________ > Leica Users Group. > See http://leica-users.org/mailman/listinfo/lug for more information