The lens profile for the Nikon 28-300 is listed under Lens Corrections when using raw files. But if you import a Tiff or a PSD, it's not there (other lenses ARE there)
Any way to get that profile to show up when working with tiffs or psds? thanks
I'm using LR 4.1
Each lens profile is originally generated either from Raw or from non-Raw test shots. Accordingly, the profile is marked as suitable for correcting either Raw, or non-Raw pictures taken with that same lens on that same camera format. So it will either show up, or not, in the automatic lens profile detection of LR or of ACR depending on the type of file involved.
Generally speaking, only Raw specific profiles are made available for many lenses... because that is the principal demand. The usual case will be that lens correction has previously happened, from the original Raw data, as part of Lightroom's general processing that has gone into any TIFF created; hence, that TIFFs can be normally assumed not to be in need of such.
This separation of two kinds of lens profile is clearly necessary in some cases; for example where aberration correction will have been already applied by the camera, but to its JPG output only; and/or, where LR is doing some (possibly different) automatic lens correction "silently", for Raw - as with its support for some m43 systems.
However where this is not the case - where no prior correction is in question - a Raw-specific lens profile can be "kludged" so as to be perfectly usable with TIFF, JPG etc - which is far better than nothing.
The way to do this is to make a duplicate copy of the profile (.lcp) concerned - changing its filename slightly to suit. Then in a text editor, in this copy, change the line which refers to "CameraRawProfile" from True to False. That's it!
If there is some double correction going on, the option is also there to selectively disable profile-based correction of vignetting, or of geometric distortion, or else to disable CA removal, as appropriate - and to then save that option into a preset or as your LR processing default.
I'm no expert on this, but I believe the purpose of a lens profile is to mathematically characterise the optical behaviour of a lens. A certain format coverage goes into the generation of the profile - be it full frame 135, APS-c crop or whatever - and that coverage can be mapped and scaled onto an image from whatever camera body one likes, using the crop factor information in the image. The magnitude and directions of all this are describable in angular terms, so different megapixel counts do not matter here AFAIK.
I presume that where there is a contribution of the specific sensor design to such things as vignetting, this is either insignificant or else reasonably constant from model to model - all I can observe, is that it seems to work fairly well when you use a profile generated from the "wrong" camera provided no active lens correction is happening elsewhere in the chain.
Provided the camera body has the same or smaller sensor coverage than the profile allows for, the same optical correction formula can still in principle be used. The lens still suffers the same systematic aberrations, whatever it is mounted in front of - and those aberrations are what you are correcting for with the lens profile; not any peculiarities of the sensor etc.
What will cause a problem, is if the TIFF you are correcting has been cropped at any point. That would invalidate the accuracy of the correction; since that relies on properly mapping the profile's field-of-view onto the camera's field-of-view.
As mentioned before, the ideal time to correct is IMO when you are still working in LR from an untouched out-of-camera file - not when you are working from a derivative, processed file.
richardplondon wrote:
The way to do this is to make a duplicate copy of the profile (.lcp) concerned - changing its filename slightly to suit. Then in a text editor, in this copy, change the line which refers to "CameraRawProfile" from True to False. That's it!
I think you have to change every line like that (most lens correction files will have a ton of them), not just "the line". I do it with global search and replace.
Lee Jay wrote:
I think you have to change every line like that (most lens correction files will have a ton of them), not just "the line". I do it with global search and replace.
It does seem to still work OK, even if you have only changed the first occurrence - at least that has been the case for me. Changing them all can't do any harm, though.
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