Original shots for lens distortion and focal length calculation

18mm

20mm

24mm

26mm

32mm

35mm

38mm

42mm

45mm

48mm

50mm

55mm

Finally got time to make a lens profile for nikkor 18-55

Nikon D3200 18-55. Visible lens breathing on sample focals(18 mm – 34 mm – 55 mm).
You can notice big changes in composition. Try to slide the images. See them at fullscreen.

This situation make camera tracking more difficult because you should take into account also the focus point when you try to define a correct focal lenght.
Lens breathing so influences the distorsion grid at fixed focal lenght.

In theory, when you try to solve a zoom curve in a shot, you should consider the distorsion as a function driven by two variables : focal lenght and focus distance. (I’m not considering the parametric variables like optical center offset, etc). The problem is that in many situations you don’t have any information on the focus distance.

During a shot you should pray to not lost/change the focus point and also hope to a have lens profiles (an undistorted grid for zoom) close to different focus distances used in action.

Original images at different focus

18mm

34mm

55mm

Perchè una semplice giornata di mare non bastava. In vino veritas

Bella giornata di mare in compagnia di zio gigio, dario stirling, stim, sirenetta, zap, adrian e iacopo. L’acqua del mare non è stata meravigliosa ma la compagnia ha reso la giornata molto piacevole. Ecco alcune foto scattate quasi al termine del viaggio (;