What EXIF lens metadata should I add for a manual Rokinon/Samyang 8mm f/3.5 fisheye?
Asked 1/11/2015
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I’m using a manual Rokinon 8mm f/3.5 fisheye on a Canon EF body, so the lens does not write its own EXIF data. I want to add lens metadata with ExifTool so software can identify the lens correctly, especially tools like Hugin/lensfun.
What should I use for the EXIF lens fields such as LensModel and LensInfo for this lens? Is there any standard naming convention or database for manual lenses, particularly for the Rokinon/Samyang-branded 8mm f/3.5 fisheye? Also, are there any other useful tags to set for lens recognition or fisheye correction software?
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
11y ago
2 Answers
4
If you want Hugin to auto-recognize and correct for the lens, then probably the right tag to use is Samyang 8mm f/3.5 Fish-Eye CS, because this is the entry in the lensfun database, which is now integrated into Hugin use. In the slr-samyang.xml file the entry is:
<lensdatabase version="1">
<lens>
<maker>Samyang</maker>
<model>Samyang 8mm f/3.5 Fish-Eye CS</model>
<model lang="de">Samyang 8mm f/3.5 Fischauge CS</model>
<mount>Pentax KAF</mount>
<mount>Canon EF</mount>
<mount>Nikon F AI</mount>
<mount>Fujifilm X</mount>
<mount>Sony Alpha</mount>
<mount>Sony E</mount>
<mount>4/3 System</mount>
<mount>Micro 4/3 System</mount>
<mount>Samsung NX</mount>
<cropfactor>1.534</cropfactor>
<type>stereographic</type>
<calibration>
<!-- Taken with some APS-C Pentax probably. -->
<tca model="poly3" focal="8" br="-0.0007764" cr="0.0013798" vr="1.0000228"
bb="-0.0002711" cb="0.0008531" vb="0.9998496" />
<!-- Taken with Nikon D7100 -->
<distortion model="ptlens" focal="8" a="0.04098" b="-0.15413" c="0.11977" />
</calibration>
</lens>
The lens is manufactured by Samyang in Korea, but is generic-branded with many many names: Rokinon, Vivitar, Falcon, Walimex, Bower, Opteka, Bell and Howell, Polar, Phoenix, and Pro-Optic are among the many names of Samyang. Weirdly, Vivitar calls it a 7mm, and Pro-Optic a 6.5mm, but they're all the same lens with the same stereographic mapping.
Also, there's an easier way than going to the command line to tag up lenses. I own a Rokinon 7.5mm f/3.5 fisheye for the micro four-thirds mount, as well as adapting several manual lenses for my Canons. I tag up the EXIF for all my manual lens and scanned film images in Lightroom with the LensTagger plugin. LensTagger is a GUI frontend for exiftool, which makes the job much easier than typing the command by hand on the command line every time. It can save "presets" of specific lenses you use often, and writes the following fields:
- Lens
- LensModel
- FocalLength
- MaxApertureValue
- FNumber
- FocalLengthIn35mmFormat
The Lens and LensModel fields can take any string, and will, indeed show up in Lightroom intelligibly. You don't need to worry about numeric coding in this case. When in Lightroom, you can set up the lens profile default for whatever tag you come up with. I tag my Rokinon 7.5 shots with "Rokinon 7.5mm f/3.5 UMC fisheye", and then set it to default to Stereographic remapping with kenw's Samyang 7.5 f/3.5 lens profile for lens correction. I'm sure there's a profile out there for the dSLR 8mm version.
Originally by user27440. Source · Licensed CC BY-SA 4.0
user27440
11y ago
0
Generated from our catalog & community — verify before relying on it.
There isn’t a single official EXIF string for a fully manual lens with no electronic communication, because the lens/camera never wrote one in the first place.
If your goal is compatibility with Hugin, the safest choice is to match the lensfun database entry, since Hugin uses lensfun for lens recognition. For this lens, that string is:
Samyang 8mm f/3.5 Fish-Eye CS
Using that as LensModel gives you the best chance of automatic recognition.
For LensInfo, use the lens’s actual specs in EXIF format: a fixed 8mm focal length and f/3.5 maximum aperture.
If you prefer brand consistency with what’s printed or marketed in your region, something like:
Rokinon 8mm f/3.5 Fisheye HD
is also sensible, but it may be less useful for automatic profile matching than the lensfun name.
So in practice:
- best for Hugin/lensfun: LensModel = “Samyang 8mm f/3.5 Fish-Eye CS”
- acceptable descriptive alternative: “Rokinon 8mm f/3.5 Fisheye HD”
- LensInfo: 8mm f/3.5 fixed lens values
There’s no broader universal standard for manual-lens naming; matching the database used by your software is usually the most practical approach.
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