Reconciling the Thick Lens Model with P2P Optical Bench

Started 4 months ago | Discussions thread
Bernard Delley Senior Member • Posts: 1,801
measure the thick lens model parameters
3

internal focus lenses change f and i of the thick lens model with focus setting.

The OB model traces the rays (currently paraxial model?)  from the data of the lens patent. By consequence it knows/tells f and i.

But, you can derive f and i of the thick lens model for "any" finite distance setting of the lens by simple measurements.

measurement get distance object-sensor plane and the LV image gives info on magnification. Repeat  measurement with the same lens settings and a known extension ring to get enough equations for the two unknowns f and i.

The measurement setup would be  improved by having the ruler along the long side of the sensor.

The effective aperture can be determined from the resulting exposure, if a target with fixed radiance is provided. -- For me, the effective aperture is the primary thing to know. The pupil factor is a correct way to deal with (bellows) extension for calculating the effective aperture for an old style lens system with fixed lens positions.  -- The pupil factor is just another parameter that varies with lens setting for internal focus lenses.

 Bernard Delley's gear list:Bernard Delley's gear list
Nikon D7200 Nikon D500 Nikon D850 Nikon AF-S Nikkor 14-24mm f/2.8G ED Nikon AF-S Micro-Nikkor 60mm F2.8G ED +10 more
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