Lens Correction For 3rd party lenses in Lightroom 4
Firstly, you will experience different support for a Raw, and for a camera JPG. Each Adobe profile provides corrections for either one, or the other.
Next, the ability of LR to recognise that a given lens has been used (both in order to list this against the picture, and in order to use the right lens correction profile) relies on the camera recording a code into the picture metadata. The nature of the lens's connection onto the camera (for older lenses) tells the camera what general class of lens it is, and then (for modern lenses) electronics inside the lens supply an actual lens-specific code. Lightroom has a table AFAIK, putting a readable lens description against each numerical code.
The camera manufacturer's own lenses get unambiguous lens ID codes according to a planned system. Third-party lens manufacturers just have to build some kind of code into their lenses for a given mount, and hope that the right thing is going to happen. However Sigma do seem to have a tendency to re-use the same code for more than one lens, which means that despite their best effort, Adobe may (understandably enough) then show a vague or even wrong description. This will affect the auto-detection of a lens correction profile too.
Say that pictures from a given lens and camera arrive labelled with a code -123 456 - which LR's list says, refers to "Sigma 18-70 f/4-5.6 or other zoom lens" - and the 35-100 f/4 is one of the other lenses that share this same coding (all completely fictional examples). If you happened to use both lenses, then LR could not separate their pictures by the lens data.
But if you only used one of these - say, the 35-100 - then, even if the description is unsuitable, you could program LR to associate a particular lens profile with this lens ID code 123 456, assuming you have this profile loaded. This is done in the Lens Corections tab, Profile panel, "Setup" menu. After manually selecting the right profile for the current image, choose "Set default.." from this menu (this user-assignment is removed again using the "Reset default" entry).
All images taken with this lens by that body, will hereafter automatically use your chosen profile - provided their lens profile Setup menu shows "Default", rather than "Auto" or "Custom".
This works for generic lens recognition as well as for specific lens recognition. For example, I use just one legacy Pentax M series lens (manual aperture) and just one legacy A series lens (auto aperture), and the camera can tell the difference between these two series in general, though not specific, terms. But this is enough to get the right profiles happening for me automatically (my more modern lenses use electronic coding which is a lot more specific).
In the event that I used two different A lenses (which appeared the same to the camera), it would be up to me to either manually select lens profiles for the various pictures according to my own knowledge of the lens used, or else to alter the picture metadata (externally) using that knowledge, so that the images could then appear to LR more distinctively labelled. A LR plugin "LensTagger" allows correction of absent, vague or wrong lens data, by this method.
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|Mar 5, 2013|
|Mar 5, 2013||1|
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