Hello everyone, I find that the distortion of the lens "Canon EF 75-300mm f/4-5.6 III " is pretty big ?
For example, when the focal is equal to 95mm, we have the PTLens distortion model with parameters: a="1.1097" b="-2.53267" c="1.80147" Ru = Rd * (a * Rd^3 + b * Rd^2 + c * Rd + d) with d = 1 - a - b -c. Note that the role Rd and Ru interchange in lensfun. So Rd is the ideal/undistorted radius, and Ru is the distorted/observed radius in the image taken by the camera. I model an image with width:height=3:2. And the half of the height is normalized to 1. For the points in this image domain, I compute the Rd (ideal/undistorted radius) with respect to the center of the image. And I want to obtain the corresponding Ru(distorted radius) according to the formula. You can see the figure for Ru--Rd at: https://dl.dropboxusercontent.com/u/68869086/ru_rd_large.jpg It seems to me that for a camera with long focal length (95mm), this kind of distortion is too big to be realistic ? In fact, for some other focal lengths of Canon EF 75-300mm f/4-5.6 III, the similar unrealistic distortion also exist according to the coefficients provided in the below. Does anyone have any comment about that ? thank you ! <lens> <maker>Canon</maker> <model>Canon EF 75-300mm f/4-5.6 III</model> <mount>Canon EF</mount> <cropfactor>1.6</cropfactor> <calibration> <distortion model="ptlens" focal="75" a="0.47796" b="-0.98871" c="0.74143" /> <distortion model="ptlens" focal="80" a="0.73577" b="-1.35909" c="0.82695" /> <distortion model="ptlens" focal="85" a="0.18115" b="-0.23959" c="0.18792" /> <distortion model="ptlens" focal="90" a="0.86117" b="-1.83099" c="1.24221" /> <distortion model="ptlens" focal="95" a="1.1097" b="-2.53267" c="1.80147" /> <distortion model="ptlens" focal="100" a="0.69157" b="-1.62711" c="1.19887" /> <distortion model="ptlens" focal="105" a="0.26436" b="-0.64004" c="0.49201" /> <distortion model="ptlens" focal="110" a="0.29814" b="-0.72389" c="0.55478" /> <distortion model="ptlens" focal="125" a="0.14326" b="-0.39549" c="0.34747" /> <distortion model="ptlens" focal="130" a="0.06614" b="-0.16946" c="0.14396" /> <distortion model="ptlens" focal="135" a="0.09381" b="-0.23171" c="0.18154" /> <distortion model="ptlens" focal="140" a="0.00267" b="-0.01604" c="0.02513" /> <distortion model="ptlens" focal="155" a="-0.00101" b="0.01422" c="-0.0204" /> <distortion model="ptlens" focal="160" a="-0.09721" b="0.28794" c="-0.28178" /> <distortion model="ptlens" focal="180" a="0.00049" b="-0.01582" c="0.01736" /> <distortion model="ptlens" focal="200" a="-0.00084" b="0.01896" c="-0.01011" /> <distortion model="ptlens" focal="240" a="0.04928" b="-0.11522" c="0.02023" /> <distortion model="ptlens" focal="255" a="0.02046" b="-0.05515" c="0.05526" /> <distortion model="ptlens" focal="280" a="-0.00732" b="0.01809" c="-0.00273" /> <distortion model="ptlens" focal="300" a="-0.00709" b="0.03947" c="-0.05006" /> </calibration> </lens> ------------------------------------------------------------------------------ Put Bad Developers to Shame Dominate Development with Jenkins Continuous Integration Continuously Automate Build, Test & Deployment Start a new project now. Try Jenkins in the cloud. http://p.sf.net/sfu/13600_Cloudbees _______________________________________________ Lensfun-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/lensfun-users
