Lightroom "Enable Profile Corrections" and m4/3 lenses

<p>My understanding, not from any Adobe documentation, but from reading various items on the web, is that all m4/3 lenses supply to the camera information that is embedded in raw files that Lightroom uses to effect corrections for distortion, vignetting, and chromatic aberration (or a subset of those), and that this occurs automatically, behind-the-scenes, is mandatory, and is not controllable by the LR user. (I don't care about JPEGs.)</p>

<p>Question #1: Is this true? (If it matters, I'm asking about Lightroom Version 5.7.)</p>

<p>#2: If true, is it also true that whether anything is actually done and what it is (e.g., chromatic aberration correction) is a trade secret, and neither Adobe nor the lens manufacturer will tell us what's going on? (The theory is that lens manufacturers don't want us to ever think that their lenses are less than perfect.)</p>

<p>To continue: I'm guessing that the purpose of the "Enable Profile Corrections" checkbox has nothing whatsoever to do with the above, but rather controls whether corrections made by a loaded profile and/or the various sliders in the Lens Corrections area are enabled.</p>

<p>#3: Is that true?</p>

<p>#4: If so, then is it true that anything effected via the Enable Lens Corrections checkbox is IN ADDITION to the secret corrections made automatically for m4/3 lenses?</p>

<p>Whoever answers authoritatively, I promise not reveal that you know any of these trade secrets. ;-)</p>

<p>Well I'll whisper..... I use 4/3 lenses and there are not any profiles that I could find for them. However, I can use every other setting/slider in lens corrections besides profile. Can't answer about the first question first sure, however you can turn lens profiles off if you choose in the Lens Correction Diagloge Box. Secondly, it doesn't seem logical to have an untouchable lens profile while at the same time offering selective lens profiles for certain lenses. You question number 3, is based on an assumption on question 2 which you haven't stated a basis for. Lastly, have you asked these questions to the lens manufacture, to Adobe and/or the Lightroom Support forum? Assuming the algorithms utilized for lens profiles are proprietary, why would they not tell you whether they use one or not. They certainly tell you of the Nikon, Canon, Leica etc. lens they do admittedly profile. Not sure why you are assuming you can't get some answers from the companies.</p>

<p>Barry: I tried really hard to be precise in my post, but, despite my efforts, I have failed to be clear. I tried to distinguish between two categories of corrections: (1) non-user-controllable ones done during raw processing based on lens info embedded in the raw file, and (2) corrections from the lens profile and other slider settings, switchable via the Enable Profile Corrections checkbox.</p>

<p>(It's very well known, and frequently mentioned in reviews, that corrections in the first category are often done in-camera for JPEGs.)</p>

<p>My #3 was about whether these two are distinct, and isn't based on any assumptions about how secret the first category of corrections are.</p>

My understanding is that the lens corrections are built in and not user controllable. From what I have seen the lenses are

designed with uncorrected faults that are corrected in software so if you could switch it off you would be sorry you did.

The profile correction option is unrelated to this I think.

<p>The OP's question comes close to mine of a few days back: <a href="/canon-eos-digital-camera-forum/00d77M">http://www.photo.net/canon-eos-digital-camera-forum/00d77M</a>. It all boils down to which settings really alter the RAW image and don't have to (or can't) be corrected in post processing.<br>

I still don't have the final answer but in case of the EOS M and 70D I made the following observations: the lens corrections (peripheral illumination correction and chromatic aberration correction) are included in the exif information, in Canon's DPP software but not in Lightroom. This shows that this correction information is available for post processing. Lens distortion is not mentioned. The question remains if lens distortion is corrected and where.</p>

<p>Jos, lens distortion on micro 4/3 *has* to be automatically corrected by RAW processing software because that is how the lenses are designed, software correction is mandatory. I can't speak for Canon but I know 100% for sure m43 corrects automatically. You only have to read lens reviews to see just how appalling the lenses are when used with a 'non-conforming' RAW converter, but since the lenses were designed to be used with software correction it really does not matter.</p>

<p>The user cannot see the corrections in Lightroom for m43, the user cannot turn them off, nor should you want to. That is how it is supposed to work.</p>

<p>Here is an example review - if you look at it you can see corrected and uncorrected comparison, it's quite horrific in the uncorrected version: http://www.photozone.de/olympus--four-thirds-lens-tests/529-oly_m918_456?start=1</p>

<p>Chris, thanks for the info/link.</p>

<p>I think Chris is right -- I've read that the automatic, mandatory corrections are for m4/3 only.</p>

<p>I see Marc. Yes, I think Chris is right. I've never seen a profile in lens correction for any 4/3 lens. As to whether your theory as to why the lens makers don't reveal this is to hide knowledge of imperfections from users is an interesting speculation, but I doubt it. Its not necessarily an imperfection and as you say several review sites mention that files are corrected in software. It has more to do with the reality of the physics of lenses and sensors. <br>

But I'm curious, why do you want to know this information?</p>

<blockquote>

<p>Jos, lens distortion on micro 4/3 *has* to be automatically corrected by RAW processing software because that is how the lenses are designed, software correction is mandatory.</p>

</blockquote>

<p>So this is true for all raw converters, not just Lightroom? </p>

No, see the photozone link where Klaus tested the lens with Rawtherapee. I'll do the same test with the 18-55 EF-M lens

to see whether Canon uses the same trick.