I wasn't getting good results with the existing lensfun profile for this lens
at anything other than close focus distances. I generated a profile using shots
at infinity and minumum, and it works much better for me. These are the numbers
for anyone who wants to try them out (and maybe confirm that it's not just my
lens that's wonky)...
<vignetting model="pa" focal="25" aperture="1.8" distance="0.25" k1="-0.7149"
k2="0.5407" k3="-0.2317"/>
<vignetting model="pa" focal="25" aperture="1.8" distance="1000" k1="-0.9456"
k2="0.4056" k3="-0.0721"/>
<vignetting model="pa" focal="25" aperture="2.5" distance="0.25" k1="-0.2119"
k2="0.0449" k3="-0.0670"/>
<vignetting model="pa" focal="25" aperture="2.5" distance="1000" k1="-0.0478"
k2="-1.0005" k3="0.5290"/>
<vignetting model="pa" focal="25" aperture="3.5" distance="0.25" k1="-0.2097"
k2="-0.0174" k3="0.0335"/>
<vignetting model="pa" focal="25" aperture="3.5" distance="1000" k1="-0.2466"
k2="0.0695" k3="-0.2812"/>
<vignetting model="pa" focal="25" aperture="5" distance="0.25" k1="-0.2242"
k2="0.0051" k3="0.0270"/>
<vignetting model="pa" focal="25" aperture="5" distance="1000" k1="-0.3798"
k2="0.4279" k3="-0.4033"/>
<vignetting model="pa" focal="25" aperture="22" distance="0.25" k1="-0.2789"
k2="0.0899" k3="-0.0123"/>
<vignetting model="pa" focal="25" aperture="22" distance="1000" k1="-0.2937"
k2="-0.0021" k3="0.0281"/>
Also attached as the full profile I'm using in case the formatting gets mangled.
Cheers,
junkyardsparkle
<lensdatabase>
<lens>
<maker>Olympus</maker>
<model>OLYMPUS M.25mm F1.8</model>
<mount>Micro 4/3 System</mount>
<cropfactor>2.0</cropfactor>
<aspect-ratio>4:3</aspect-ratio>
<calibration>
<distortion model="ptlens" focal="25" a="0.00454" b="-0.0141" c="0.00283" />
<vignetting model="pa" focal="25" aperture="1.8" distance="0.25" k1="-0.7149" k2="0.5407" k3="-0.2317" />
<vignetting model="pa" focal="25" aperture="1.8" distance="1000" k1="-0.9456" k2="0.4056" k3="-0.0721" />
<vignetting model="pa" focal="25" aperture="2.5" distance="0.25" k1="-0.2119" k2="0.0449" k3="-0.0670" />
<vignetting model="pa" focal="25" aperture="2.5" distance="1000" k1="-0.0478" k2="-1.0005" k3="0.5290" />
<vignetting model="pa" focal="25" aperture="3.5" distance="0.25" k1="-0.2097" k2="-0.0174" k3="0.0335" />
<vignetting model="pa" focal="25" aperture="3.5" distance="1000" k1="-0.2466" k2="0.0695" k3="-0.2812" />
<vignetting model="pa" focal="25" aperture="5" distance="0.25" k1="-0.2242" k2="0.0051" k3="0.0270" />
<vignetting model="pa" focal="25" aperture="5" distance="1000" k1="-0.3798" k2="0.4279" k3="-0.4033" />
<vignetting model="pa" focal="25" aperture="22" distance="0.25" k1="-0.2789" k2="0.0899" k3="-0.0123" />
<vignetting model="pa" focal="25" aperture="22" distance="1000" k1="-0.2937" k2="-0.0021" k3="0.0281" />
</calibration>
</lens>
</lensdatabase>
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