RT does not recognize my lens

(Luis A Florit) #1

I have a manual Laowa 7.5mm lens that I use in an Olympus EM1mkII, and I want RT to recognize the lens, mainly to apply a Dynamic profile.
So, I am trying to write the EXIF using exiftool. I did the following:

exiftool -Lens=‘Laowa 7.5mm f/2 MFT’ -MaxApertureValue=2 -MaxApertureAtMaxFocal=2 -MaxApertureAtMinFocal=2 -FocalLength=7.5 -FocalLengthIn35mmFormat=15 -MinFocalLength=7.5 -MaxFocalLength=7.5

Yet, RT says that my lens is unknown.

I guess that I am writing the wrong EXIF tags into the ORF file. Could you please tell me which tags should I write?

BTW, I added the FL and Aperture, and I can recognize the lens by those parameters and use this for the Dynamic profile (I have no other 7.5mm lens).



(Mica) #2

Does LensFun support that lens? Also what version of RT?


Lensfun does not support this lens yet, see link:


In my experience submitting images for the Lensfun team to add a lens to the list is straight forward and pretty quick (details are given via the link above). You then have to make sure your software is using the latest Lensfun data.

(Luis A Florit) #4

Actually, my question was easier: how to write Lens EXIF data onto the raw file in order for RT to recognize the lens and apply a dynamic profile. My profile already fixes the lens distortions.

(Karl) #5

If you already have profile data, try using “Lens ID” instead of “Lens” as the EXIF tag.

(Luis A Florit) #6

I’m not using the lens since, since I don’t know how to add that with exiftool in such a way that RT recognizes it (using rawtherapee-5.3-2.1.x86_64). Instead, I’m using just the focal length of 7.5mm (I have no other lens with that focal length) as a workaround. Probably the problem is that I am not very familiar with exiftool…?

In fact, I’m having problems with RT recognizing the EXIF at all. Sometimes the Dynamic profile is triggered, sometimes it is not, even with pictures taken 1 or 2 seconds apart with exactly the same settings.

Is there a known issue with RT regarding this?

(Morgan Hardwood) #7

@Luis_A_Florit upload a sample raw file straight from your camera, without editing it in any way, then we can take a look.

(Luis A Florit) #8

I think I know what is happening.
I have two dynamic profiles, one for the 7.5mm lens, and another for ISO>500. If the image falls in both, it only applies the second one (ISO>500). I thought they were ‘accumulative’, according to what I understood in RT site (https://rawpedia.rawtherapee.com/Dynamic_processing_profiles):

When a picture is edited for the first time, the list of rules is scanned, and all the profiles that match are combined (in the order given, so later rules can override earlier ones) to build the initial processing profile.

It seems I don’t understand what this “combined” means…

(Alberto) #9

means applied in sequence, from top to bottom. if the profiles are partial and don’t overlap, they are effectively merged. but if both contain settings for the same tool, the latest one will overwrite the earliest. (this is a feature btw)


Unfortunately, lens recognition is not so straightforward.
Each camera manufaturer code the lens type/model in a cryptic way inside the Makernote (numerical lensid for Nikon for instance)
So Each SW has to decode the information to generate the lens name, mainly based upon exiftool or exiv2.
For Olympus brand, it is done in RT inside rtexif/olympusattribs.cc, based on exiv2 I think. I cannot see here a ref to your lens.
If you want some decisive information download example as @Morgan_Hardwood asked for.
In meantime, the best you can do is to test your modif with exiv2 or exiftool (try exiftoolgui for that)

(Luis A Florit) #11

Aha! The key word is “partial”. After several years using RT I didn’t know that CNTR-SAVE thing even existed. Sorry. I know now how to build a workaround.