Links or formulas to obscure but often asked questions

Posted: Fri Jul 09, 2010 7:07 pm

This page is useful to calculate the required lens focal length to take a picture of an object of size yo at a distance xo in order to generate an image of size yi on the film (or the CCD/C-MOS imager). The film plane is located at a distance xi.

http://www.giangrandi.ch/optics/lenses/focalcalc.html

Determining the magnification ( X ##) of a particular lens and its relationship to the human eye (this is used in binoculars). Lens focal length x [sensor crop factor] / 50 (50 is used as it represents a view closest to what the human eye does)

Example: My 70-200 VR at 200mm with a D200 which has a crop factor of 1.5 (200 x 1.5)/50 = 6
So my 70-200mm VR at 200mm has a magnification of 6x

Determining the Zoom magnification (X ## Zoom) This is a relationship of a zoom lenses shortest and longest focal lengths. Simply divide the longest focal length by the shortest focal length to obtain the Zoom magnification.

Example: My 35-135mm Nikon is 35 at the shortest focal length and 135 at the longest focal length.
135/35 = 3.85...
So the Zoom Magnification of the lens is 3.85X roughly

Macro/Micro calculations (to many to list):

http://www.peterforsell.com/macro.html

Moon Phase for Palm OS:

http://www.freewarepalm.com/astronomy/moonphase.shtml

Tide Tool for Palm OS:

http://www.toolworks.com/bilofsky/tidetool/

Pinhole Toolkit Palm OS:

http://www.freewarepalm.com/calculator/pinholetoolkit.shtml

Stereo Calc for Palm OS:

http://www.freewarepalm.com/calculator/stereocalc.shtml