Hi knowledgeable friends,

This is not really leica-related. Just come to mind the lens in the P&S camera compared to that for RF or SLR. The glass in P&S cameras is normally much smaller than that for RF or SLR (given the same design and name such as 35mm f2.8 Sonnar T* in Contax T3 P&S camera versus the normal 35mm Sonnar for Contax SLR). Will the picture quality be different because of the size of the glass - bigger glass catches more light thus better image? Best Regards,

-- tom tong (tom.tong@ckh.com.hk), December 17, 2001

Answers

As I understand it, the image quality of smaller aperture lenses is likely to be better, all things being equal, than that of wider aperture lenses, so your 35/2.8 may well be give better results than a 1.4 version of the same design. Bigger glass just means you can shoot slower film in less light, which is handy.

-- rob (rob@robertappleby.com), December 17, 2001.

Size of lens of a given focal length for a given film format is related to lens design (focusing barrel, iris management ring, AF mechanisms, optical design) and distance from lens to film plane.

A SLR needs loads of room for the mirror. Compared to RF or compact AF bodies, this pushes the lens further for the film, and therefore requires larger diameters of lens elements in order to bring a given quantity of light to the film. The integration of mount and needed linkages, aperture ring and focusing ring (and eventual AF motor or shafts) also take their toll on size of the lens.

You may therefore have similar tessar or sonnar designs (to speak contax), and equivalent optical performance, between an ultra compact sonnar such as the T3's or ultra compact tessar such as Yashica's T5, and their SLR siblings.

Larger size does not mean better lenses.

-- Jacques (jacquesbalthazar@hotmail.com), December 17, 2001.

Only in telescopes is the front element size of extra importance. I can assure you from personal experience that the small Sonnar on the T3 is as good of a 35mm focal length lens as you will find regardless of the size. Another superb lens I own with a very small front element is the 135mm Tele Elmar that has takes a 39mm filter size even for a telephoto of that length.

-- Andrew Schank (aschank@flash.net), December 17, 2001.