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Without coding, with IR filter: lens detection on or off?


borowiec

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I just got an IR cut filter for my 1970s 28 Elmarit. The lens isn't coded and I don't have time to jury-rig coding with paint or markers before a shoot tomorrow. Will I be better off setting the camera to Lens Detection Off or to On + UV / IR? At first glance, looking at some test shots, it seems that the cyan cast is less noticeable with it set to On + UV / IR. Does that make sense?

Thanks!

Andrew Borowiec

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Coding causes the camera firmware to recognize lens type and filter. Without coding I doubt you will reap the benefit of selecting lens recognition 'on'. Otherwise I am sure Leica would have offered that as a menu option.

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With any lens shorter than 50mm you do need coding to counteract the cyan shift that the filter produces around the edges and in the corners. There's no way around that. Rube Goldberg/Heath Robinson software procedures are no real answer. And the camera must be set to 'ON + UV/IR'.

 

With the longer lenses, you can leave the setting as above. Without any coding input, the camera will apply a generic, slight correction that is realy aimed at the weak internal filter. I have seen no problem here.

 

The old man from the Age of Infra-Red Film

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Well, given the preponderance of opinion, I decided to attempt coding. However, I can find codes for the 3rd and 4th generation 28 Elmarits as well as the current ASPH lens, but none for mine (2nd. generation). And all three of those are different, so which should I use? Mine is also not on the list of lenses that Leitz says can be sent to them for coding

Andrew Borowiec

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You are mistaken, Harold. If a lens is coded the vignetting and (if UV/IR is selected) cyan drift corrections are made in the camera before the DNG is written.

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If you shoot Raw, the lens info is in the exif data but nothing is done in camera . It is up to the raw processor to apply specific corrections (or not ).

 

Regards ... Harold

 

Well... Actually, with lens correction set to On + UV/IR the vignetting and cyan corrections ARE applied to the dng raw file...

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Well, given the preponderance of opinion, I decided to attempt coding. However, I can find codes for the 3rd and 4th generation 28 Elmarits as well as the current ASPH lens, but none for mine (2nd. generation). And all three of those are different, so which should I use? Mine is also not on the list of lenses that Leitz says can be sent to them for coding

Andrew Borowiec

 

Mine too was uncodable by Leica... I think for the mount has a screw along the "bit strip" and this is an "unsupported codable configuration" in Leica view (not wrong, milling CANNOT be done); but painted DIY coding works, and you can use Elmarit 28 3rd generation code (is one of the easiest... 000011 - a big black point acts as two...)

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Maybe my expectation is too low, but uncoded lenses wider than 35mm works perfectly fine unless I am shooting white wall or blue sky... I don't shoot those things often, so I don't see much problem on my images without coding... But I do use UV/IR cut filters on every lens I use.

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Jaap is correct, of course. To amplify that, if the new DNG 1.3.0.0 standard is implemented, in the future it is possible we may have the option to adjust those corrections and others after the fact as they will move from the firmware to the converter. Should be good news for camera DNG processing time too.

You are mistaken, Harold. If a lens is coded the vignetting and (if UV/IR is selected) cyan drift corrections are made in the camera before the DNG is written.
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