Top Picks for Leica 'M' Lenses 1-360-656-6835 Let me start by saying that all used Leica lenses are great performers and a good way to save some money.  Occassionally you can get current lenses in good condition on the used market, but be aware and do your homework and buy from a reputable dealer/private party that knows their lenses.  Don't get stuck with a lens that needs cleaning or repair that someone found in an attic in Florida (Humidity kills lenses) and put on E-Bay.  The new Leica lenses are exemplary and all are Superb if you have the money and can afford them.  If not, here are my picks to assemble the best used affordable Leica lenses for your kit.  All of these lenses (except the 28mm) use the standard Leica 39mm filter thread.  The 28mm uses a 49mm filter.  They are also small & lightweight which means they are easy to carry.  The 90mm & 135mm also have removeable lensheads that can be used on the Visoflex system. Focal Length Model F-Stop Starting SN# Ending Sn# Type Years Produced Elements/Groups 28mm Elmarit 2.8 2977551 N/A 3 1979-1993 8/6 35mm Summicron 2.0 2970000 3731200 4 1972-1997 7/5 50mm Summicron 2.0 1303000 2260000 1 1956-1968 7/6 90mm Elmarit 2.8 1645300 2730000 1 1959-1974 5/3 135mm Tele-Elmar 4.0 2077000 3750000 1 or 2 1965-1992 5/3 If you are looking for Maximum Sharpness and Contrast and money is not an issue, simply purchase the newest generation of lenses. Lens Guide: Elmars - Small and Lightweight.  Some are collapsible for low profile.  They are Sharp and have a flat field much like macro lenses.  In the older days many doubled the ise of the elmars as enlarger lenses or repro lenses because of there flat field characteristics.  This means that they are very sharp from edge to edge.  Most of these lenses are highly under rated in todays world of speedy lenses, but to me the Elmars are some of my personal favorites.  Great travel lenses, especially for landscapes and scenics. Elmarits - An extension of the Elmars, but not collapsible and a little larger.  Not as fast as the Summicrons but smaller in size and weight. Summicrons - Small lenses with the reputation of being the standard by which all other lenses are judged for sharpess and contrast. Summilux's - The Speed Denoms.  Leica's Fast lenses - when you need light gathering power or subject isolation these are the lenses to get.  As sharp as the Summicrons when used at the same aperture.  Larger and Heavier than Summicrons. Specialty Lenses - Noctilux (the Fastest Lens in the World at F1). Dual Range and Macro lenses for close ups.  Super Angulons for Wide Angle and the Thambar for flatterinf soft focus portraits. Lens Terms: APO - Apochromatic, focuses all three colors of the light spectrum at one point.  Maximum sharpness and white objects show no color fringing.  All other lenses are Achromats.  Leica does not throw this term around losely like other Manufacturers for marketing reasons.  An APO Leica lens is so perfect that it does not need to be re-focused when shooting infrared film. Asph. - Aspheric lens elements are essentially non-round lens elements that are shaped more rectangular.  They are used mainly in Wide Angle lenses to reduce distortion characteristics of lenses.