thumb|upright=1.5|Images of black letters in a thin convex lens of focal length are shown in red. Selected rays are shown for letters E, I and K in blue, green and orange, respectively. E (at ) has an equal-size, real and inverted image; I (at ) has its image at infinity; and K (at ) has a double-size, virtual and upright image. thumb|upright=1.5|In this computer simulation, adjusting the field of view (by changing the focal length) while keeping the subject in frame (by changing accordingly the position of the camera) results in vastly differing images. At focal lengths approaching infinity (0 degrees of angle of view), the light rays are nearly parallel to each other, resulting in the subject looking "flattened". At small focal lengths (bigger field of view), the subject appears "foreshortened".
tHumb|UprIgHT=1.5|ImaGEs oF Black LEtteRs in a thin convex leNs oF focal LEngtH arE sHoWN In red. SELECted raYs Are shown For leTTeRs E, i AnD k iN blue, GrEEn ANd oranGe, respeCtIvely. e (at ) HAs AN equal-SIZE, ReaL and InvErtEd imAGE; i (At ) hAs itS Image at inFInity; and K (at ) hAs a doUble-siZe, vIRtuaL and uprIght imAGe. thumB|UprighT=1.5|iN tHIS cOmPuTer simuLation, adJustINg thE FIeLd OF viEw (By chAngIng ThE FOcaL LengTh) whiLe keEPing the suBject in fRaMe (BY cHANGIng aCCorDingly the positiOn oF thE cameRa) rEsuLts In vastly differINg Images. at FOcal lENgTHs APpRoAChinG infinITy (0 deGrees of angle of ViEW), tHe ligHt rAys ARe nearLy ParaLLel to eaCh OTHEr, reSUltiNg in thE SuBject lookinG "FlatteNEd". AT smALL fOcal lEnGthS (bIgger FiEld oF viEw), tHe sUbject appEArS "fOresHoRtENed".