Leica 90mm F2.8 Elmarit & Tele-Elmarit This is the most popular telephoto focal length for most peoples Leica camera bags.  The 90mm F2.8 is fast enough for most situations and capable of providing a very shallow depth of field when necessary.  The 90mm F2.8 has been provided to us in two types each with two versions, the Elmarit & Tele-Elmarit name with non-removable lens heads, true telephoto construction and shorter lens body lengths.  The first version of the 90mm Elmarit had a removable lens head for Visoflex use with an optical formula of 5 elements in 3 groups.  It was considered to be a variation of the 135mm Hektor lens.  The first version of the Tele-Elmarit was also known as the 'FAT' elmarit.  The optical formula was  different than the Elmarit with 5 elements in 5 groups, but note that the Elmarit stayed in production with the Tele-Elmarit until 1974.  Collectors like these lenses for their unique appearance which is Fat and Short (it's also easier to fit into your camera bag).  The second version of the Tele-Elmarit was Thin and Short in appearance.  It also had a change in optical formula with the reduction of one element due in part to the introduction of new glass formulations.  The second version of the Elmarit appeared in 1989 and its optical formula changed to 4 elements in 4 groups also.  This lens is also of true telephoto construction.  The new lens is also compact and incorporates a built in telescoping hood. Collectors seem to gravitate towards the First version Elmarit which was made in small numbers in black instead of chrome. and is generally the most expensive and rarest of these lenses (shown below).  The first version Tele-Elmarit 'FAT' is also popular among collectors for its small production numbers and unique appearance.  The first version chrome Elmarit and Second version Tele-Elmarit can be found at reasonable prices on the used market.  They are all Fine performers although I prefer the First Elmarit and the First & Second Tele-Elmarit's because of their compactness, nice & wide focusing ring and 39mm filter size.  This lens is great multi-purpose lens that is perfect for people and landscape photography.   90mm F2.8 Elmarit  1959-1974 Type 1 SN#1,645,300-2,730,000 Finish Mostly Chrome, Some Black Mount Rigid, Removeable Head Lens Elements 5 in 3 Groups Filter Size 39mm Apertures F2.8-F22 Angle of View 27 Degrees Minimum Focus Distance 1 Meters Units Produced 35,000 approx. Weight 320 Grams 90mm F2.8 Tele-Elmarit  1964-1974 Type 1 SN#2,000,000-2,730,000 Finish Mostly Black, Some Chrome Mount Rigid Lens Elements 5 in 5 Groups Filter Size 39mm Apertures F2.8-F22 Angle of View 27 Degrees Minimum Focus Distance 1 Meters Units Produced N/A Weight 355 Grams 90mm F2.8 Tele-Elmarit  1973-1989 Type 2 SN#2,585,001-3,500,000 Finish Black Mount Rigid Lens Elements 4 in 4 Groups Filter Size 39mm Apertures F2.8-F16 Angle of View 27 Degrees Minimum Focus Distance 1 Meters Units Produced N/A Weight 225 Grams 90mm F2.8 Elmarit  1989-Current Type 2 SN#3,480,000 to Current Finish Chrome, Black & Titanium Mount Rigid Lens Elements 4 in 4 Groups Filter Size 46mm Apertures F2.8-F22 Angle of View 27 Degrees Minimum Focus Distance 1 Meters Units Produced In Production Weight Black 410 Grams Chrome 560 Grams The second version Tele-Elmarit was also made in limited numbers as a special 70th anniversary model.