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05-14-2019, 02:03 PM   #1
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LR Lens Correction Profiles FF vs Crop

So... I'm just wondering, when you apply a lens profile correction in LR, is it universal or is it camera specific?

So let's pretend I use the HD DA 20-40 on a K-1, a camera body it is not recommended for (however you do seem to get away with certain focal lengths with reasonably good images etc). When applying the correction there is no 'camera body' to select, but then the program seems to know you're using K-1 (it's in the EXIF), and often can auto detect the lens, so all you need to do is pull the menu down and select 'Pentax' and it does the rest.

However, is it correcting the lens for the crop bodies such as KP and applying that profile on the K-1? So perhaps with it's vignette tackling perspective of the profile, it's applying that weaker because it simply doesn't vignette that hard on it's proper 'meant-to-be' crop bodies? This then made me think about other lenses that are universally swappable between sensor types, such as the FA Ltd's. Meant for FF but work fine for crop, does this mean when applying those Lens Correction profiles when it's sitting on a crop body is perhaps overkilling some correction issues such as vignetting?


TIA!

Bruce

05-14-2019, 02:15 PM   #2
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Lightroom lens profile take into account the sensor size and the specific lens. There are a series of profiles including zoom lens focal length.

Adobe does provide a free tool to make your own lens profiles, but it is not a trivial undertaking from what I can see
05-14-2019, 02:39 PM   #3
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QuoteOriginally posted by BruceBanner Quote
So... I'm just wondering, when you apply a lens profile correction in LR, is it universal or is it camera specific?
They are universal in the sense that a particular lens will behave the same within its image circle regardless of the camera or format for the capture. That being said, LR will not allow a mismatch between small image circle capture and a larger format frame.* As noted above, you can make your own and even donate them to Adobe if they are any good. It is my understanding that the profiles for the various vintage Asahi/Pentax lenses bundled with ACR are user-donated.

For more information:

Julieanne Kost's Blog | Create your own Lens Profiles

The user guide for the Lens Profile Creator tool provides the basic steps of what is done. Note that user-created profiles are specific to camera/lens combinations.

http://wwwimages.adobe.com/content/dam/Adobe/en/products/photoshop/pdfs/lens..._userguide.pdf


Note: LCP files contain XML (Adobe XMP) and are both machine and human readable.


Steve

* At least that is my memory of things.

Last edited by stevebrot; 05-14-2019 at 03:25 PM.
05-14-2019, 03:30 PM   #4
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If you shoot with multiple camera bodies with different sensors, you will have to create profiles for each camera/lens combination.

While it is true that lens behaviour is fixed the camera sensors handle captures differently. To be more precise, comparing FF to Crop sensor, distortion and vignetting will not be as noticeable on the crop sensor due to using the central are of a FF lens.

Should you crave more detail study the Adobe documentation
http://wwwimages.adobe.com/www.adobe.com/content/dam/acom/en/products/photos..._userguide.pdf

Keep in mind that a single iteration for a camera/lens combination will optimally correct for the behavior of a single given lens setup (focal length, aperture, and focus distance). Experiment with applying your initial LCP results to images of the same camera body and lens model that vary in focal length, aperture, and focus distance when compared to the LCP data. To achieve optimal results, calibrate and append an LCP file with different shooting iterations that match the lens settings you use the

05-14-2019, 06:26 PM   #5
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QuoteOriginally posted by BruceBanner Quote
However, is it correcting the lens for the crop bodies such as KP and applying that profile on the K-1? So perhaps with it's vignette tackling perspective of the profile, it's applying that weaker because it simply doesn't vignette that hard on it's proper 'meant-to-be' crop bodies? This then made me think about other lenses that are universally swappable between sensor types, such as the FA Ltd's. Meant for FF but work fine for crop, does this mean when applying those Lens Correction profiles when it's sitting on a crop body is perhaps overkilling some correction issues such as vignetting?
Below is a snippet from the .lcp file for the HD DA 20-40 in your example*. The snippet is one of several hundred almost identical items in a long list that defines the lens correction profile. The actual correction factors for this combination of focal length, focus distance, and aperture are bound by the PerspectiveModel tagset. Note that while the lens and settings are quite specifically identified, there is no camera reference. The closest thing might be the SensorFormatFactor which identifies the lens as being crop format with a multiplier of 1.5.

Code:

<rdf:li>
<rdf:Description
stCamera:Author="Adobe (www.adobe.com)"
stCamera:Make="RICOH IMAGING COMPANY, LTD."
stCamera:CameraRawProfile="True"
stCamera:LensID="8 209"
stCamera:Lens="HD PENTAX-DA 20-40mm F2.8-4 Limited"
stCamera:LensInfo="200/10 400/10 28/10 40/10"
stCamera:CameraPrettyName="RICOH IMAGING COMPANY, LTD."
stCamera:LensPrettyName="HD PENTAX-DA 20-40mm F2.8-4 Limited"
stCamera:ProfileName="Adobe (HD PENTAX-DA 20-40mm F2.8-4 Limited)"
stCamera:SensorFormatFactor="1.5"
stCamera:FocalLength="20"
stCamera:FocusDistance="0.28"
stCamera:ApertureValue="6.918863">
<stCamera:PerspectiveModel>
<rdf:Description
stCamera:Version="2"
stCamera:ResidualMeanError="0.000024"
stCamera:ResidualStandardDeviation="0.000031"
stCamera:RadialDistortParam1="-0.140895"
stCamera:RadialDistortParam2="0.071562"
stCamera:RadialDistortParam3="0.005048">
<stCamera:VignetteModel
stCamera:ResidualMeanError="0.000064"
stCamera:VignetteModelParam1="-0.349643"
stCamera:VignetteModelParam2="-0.05172"
stCamera:VignetteModelParam3="0.029851"/>
</rdf:Description>
</stCamera:PerspectiveModel>
</rdf:Description>
</rdf:li>
I did a thorough search and there are no correction settings for other than SensorFormatFactor = "1.5". I don't have files to test, but suspect that Adobe will only allow this profile for a cropped capture or that the profile might not work well if the matter were forced.

As for the FA 77/1.8 Limited, its SensorFormatFactor = "1", with no entries for other than 1. Adobe obviously deals with the cropped sensor case since this profile is offered by Lightroom for my K-3 images with no fiddling required. Since a crop is a crop is a crop, there are multiple ways the software might deal with the smaller capture format. After all, it manages to work with user crop applied as part of processing.


Steve

* PENTAX (HD PENTAX-DA 20-40mm F2.8-4 Limited) - RAW.lcp

Last edited by stevebrot; 05-14-2019 at 06:36 PM.
05-15-2019, 03:25 AM - 1 Like   #6
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The only way to be sure what happens with the Adobe lens profiles is to ask Eric Chan (creator of application?) Senior Principal Scientist at Adobe

The key I believe is the crop factor and also note that the camera used can be identified. Lens profiles for Canon, Nikon, Ricoh seem to follow the camera naming convention with the information gleaned from the exif data.
QuoteQuote:
<rdf:li>
<rdfDescription
stCamera:Author="Adobe (www.adobe.com)"
stCamera:Make="Canon"
stCamera:Model="Canon EOS 50D"
stCamera:UniqueCameraModel="Canon EOS 50D"
stCamera:CameraRawProfile="True"
stCamera:LensID="4150"
stCamera:Lens="EF-S10-18mm f/4.5-5.6 IS STM"
stCamera:LensInfo="10/1 18/1 0/0 0/0"
stCamera:CameraPrettyName="Canon EOS 50D"
stCamera:LensPrettyName="Canon EF-S 10-18mm f/4.5-5.6 IS STM"
stCamera:ProfileName="Adobe (Canon EF-S 10-18mm f/4.5-5.6 IS STM)"
stCamera:SensorFormatFactor="1.6"
There do not appear to be any restrictions on applying any lens profile for any camera to any image - other than as noted the results are not necessarily going to be good

If you wish to create your own profiles using Adobe Lens Profile creator and you have both FF and crop bodies and want to profile a crop lens then it is seen as best practice to use the FF body with crop lens as it can sample more image data

You can use silly names that will be added to the profile and identify it, however the camera details will be taken from image exif. TBH I have not found the need to actually create a lens profile as those cameras I use seem well served by Adobe offerings and of course I can use manual intervention.
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05-15-2019, 04:56 AM   #7
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As per usual you all did a great job of getting yer nerds on and confusing the hell out of me

I'll just make a couple of points;

- I won't be making a lens profile, too advanced for me, don't have the time right now either.

- If I put the HD DA 20-40 on my KP and take a shot, lets say 40mm f4, then I take that image and apply Lens Profile Correction on it, which as we all know just gives a pull down menu for Pentax and then typically finds the lens profile automatically. Certain things can be seen straight away, a vignette treatment and distortion correction. I'm expecting the correction applied here was for this lens on a crop body, because that's what the lens officially supports. So I am 'trusting' the correction to be accurate for crop bodies.

- If I put the HD DA 20-40 on my K-1 and take a shot, lets say again 40mm f4, and then apply Lens Profile Correction, I am expecting it to tackle the level of vignetting to be removed for crop sensor only, and because there is so much more vignette on the K-1 (possibly too much to ever truly get rid of) then it will not necessarily do this task that well... not as well as perhaps if someone had the HD DA 20-40 on the K-1 and then set about making a lens profile correction, surely things like distortion and vignette treatment values would differ quite a lot... no?

Because after all the responses I'm not really getting a clear answer as to what you all think is happening right now if I do the latter. To say the correction is 'universal, regardless of body attached' doesn't sit right with me, I mean you can go too far with vignette removal can you not? The amount needed for the HD DA 20-40 on FF would be much more than the crop, to apply that same amount to crop would be at a level of detriment?
I mean... perhaps with the K-1 you have to go to maximum for vignette removal as well as alter the midpoint and thus adjust other parameters to compensate, whereas crop body it's only necessary to just ease back on the vignette and not even touch the midpoint?

Does that make sense?

I'm kinda expecting in the drop down menu for which lens to choose for it to say something like "HD DA 20-40 FF"...

But then this all made me thinking about lenses that are FF but then might not need as 'severe' correction for crop bodies (like a FA77 or FA43, which we know can vignette quite badly at wide open apertures on FF, then surely this means on crop the vignetting is not as bad..)
05-15-2019, 02:34 PM   #8
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QuoteOriginally posted by TonyW Quote
The only way to be sure what happens with the Adobe lens profiles is to ask Eric Chan (creator of application?) Senior Principal Scientist at Adobe

The key I believe is the crop factor and also note that the camera used can be identified. Lens profiles for Canon, Nikon, Ricoh seem to follow the camera naming convention with the information gleaned from the exif data.
There do not appear to be any restrictions on applying any lens profile for any camera to any image - other than as noted the results are not necessarily going to be good

If you wish to create your own profiles using Adobe Lens Profile creator and you have both FF and crop bodies and want to profile a crop lens then it is seen as best practice to use the FF body with crop lens as it can sample more image data

You can use silly names that will be added to the profile and identify it, however the camera details will be taken from image exif. TBH I have not found the need to actually create a lens profile as those cameras I use seem well served by Adobe offerings and of course I can use manual intervention.
Where did you get the PDF for the chart?


Steve

05-15-2019, 02:37 PM   #9
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QuoteOriginally posted by BruceBanner Quote
I'm expecting the correction applied here was for this lens on a crop body, because that's what the lens officially supports. So I am 'trusting' the correction to be accurate for crop bodies.
That particular lens profile is specific to crop sensor.

QuoteOriginally posted by BruceBanner Quote
- If I put the HD DA 20-40 on my K-1 and take a shot, lets say again 40mm f4, and then apply Lens Profile Correction, I am expecting it to tackle the level of vignetting to be removed for crop sensor only,
Assuming you are shooting in crop mode.

If you defeat the feature and shoot in FF mode, all bets are off; the profile being defined for APS-C frame.


Steve

(...covered this above as well...)

Last edited by stevebrot; 05-15-2019 at 02:46 PM.
05-15-2019, 02:39 PM   #10
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QuoteOriginally posted by BruceBanner Quote
I'm kinda expecting in the drop down menu for which lens to choose for it to say something like "HD DA 20-40 FF"...
You may be waiting a long while since the name on the profile list is from the file name for the .lcp file.


Steve

Last edited by stevebrot; 05-15-2019 at 03:39 PM.
05-15-2019, 03:03 PM   #11
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Trying not to stray into too much detail a profile made for a FF lens should have the required information to correct for lens distortions and vignetting providing that the crop factor for the camera is known. With the key crop factor identified the profile will adjust image data accordingly.

Adobe recommends f/8 -f/11 as a general guideline for profiles but warns that if you are using lens wide open you should build the profile including these apertures. Advanced profiling for wide angle zooms can require 70+ calibration images, mid to long zooms and primes may require half that!

---------- Post added 05-15-19 at 03:16 PM ----------

QuoteOriginally posted by stevebrot Quote
Where did you get the PDF for the chart?


Steve
The PDF's (many!) are included with the Lens Profile Creator. Rec. is to print as large as possible and PDF provided up to A0 size. To clarify the screen grab was just an old test of sample images provided with the LPC.
05-15-2019, 03:30 PM   #12
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QuoteOriginally posted by BruceBanner Quote
...

I'm kinda expecting in the drop down menu for which lens to choose for it to say something like "HD DA 20-40 FF"...
You could edit the file to display that or any name but there is little point as the lens design is for crop.

Just for fun!, here is a Nikon FF capture with 50mm f/1.8 Nikkor, selecting your Pentax 20-40. By no means horrible (lens profile that is not image content ), apart from small, incorrect, but not objectionable distortion correction, it lightens the corners correcting for vignetting that is not actually there.
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