Monday, December 7, 2020

LensSim: Data Sheet

Another minor tweak to LensSim, this time to tidy up the 'Lens Data Sheet'.

The functionality is:

  • Add your lens name on sheet 1;
  • Enter your lens data on sheet 2;
  • Set the focus to the minimum, in order to get info on lens extension;
  • Adjust the graph's dimensions and the lens position as required;
  • Take a screen grab, eg Shift-Win-S on a Windows 10 PC.

As an example, here is a screen grab I just took of a hypothetical 24mm lens:

This data sheet provides all the key info, eg:

  • The lens name
  • The lens input info
  • The position of the front principal, the zero of the hyperfocal and DoF distances. Plus this is where the zero of the hinge height sits in a tilt/shift lens;
  • The position of the entrance pupil, important to know if wishing to calculate depths of field 'correctly', plus this is the zero of the field of view and the pano pivot location;
  • The FoV at the focus position, hence set focus to the MFD to get the bellows impact on the FoV; plus the FoV at infinity, ie the maximum FoV;
  • The width of the hiatus is simply focal length divided by the aperture number at infinity. 

Finally, LensSim is also useful if you wish to explore how a lens changes its output characteristics, as you change various input data, eg MFD, MaxMag, Pupil Mag, Focal Length, etc. Plus remember you can set any LensSim slider to play an animation.

Bottom line: Using LensSim you can create a data sheet for each of your lenses, eg adding additional info as required.

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