The Canon f1.8 50mm

[klindup]

Canon say that their 1.8 50mm lens uses Gaussian optics.  Can anyone tell me what this type of construction looks like?  I thought that Gaussian optics referred to the proof by Gauss that one did not have to take account of all the lens elements when making calculations about a lens and that all you had to consider were the six Gauss points for any lens or system of lenses.

[Bob Atkins]

In this context I think "Gaussian" is a description of a a lens (usually 4 to 6 elements) which is more or less symmetrical about the aperture stop. It doesn't strictly refer to "Gaussian" optics, rather it's the name given to a particular design.

If you look at the EF 50/1.8 (and the current EF 50/1.8 II which is optically identical), you'll see that the design, while not exactly symmetrical, is pretty close, with three elements on each side of the aperture stop of similar types, with the types in the same order and in a similar configuration.

It's an excellent design for a simple prime lens the the 50mm focal length range.

[klindup]

Thanks Bob, now I understand.  I can relate to such a lens and appreciate its benefits.  That's another lens I will add to my kit.  As a newcomer to digital photography I value the advice and information that is available on this site.