Here's the first of a series of small tests of vintage glass, using the NEX-5N. I have started with "the" classic lenses for 35mm cameras:

All these lenses are milestones for the development of the 35mm cameras. Both the Elmar 3.5/5 cm as well as the Tessar 2.8/5 cm are based on the original Tessar 1:6.3 design by Paul Rudolph (1902). They were essentially a simple cemeted dublet (made from classical glass) with two additional lenses (using barium and fluoride glass) in front for the correction of the astigmatism. The most important was probably the Elmar, since it paved the way for all 35 mm cameras.

Technically, however, Ludwig Berteles Sonnars were outstanding: Around 1932 the Zeiss Sonnar 1.5/5cm was as good at f1.5 as Leitz' best lens (the Elmar 3.5/5cm) at f11! The Sonnar is an unique and outstanding design, derived from the original Cooke Triplet. The general history of the Sonnars is described here (published in the Sony Fotospiegel 142).

Of course Leitz tried to change the unfavourable situation - but they failed, for at least 10-15 years: Their Xenon 5cm 1:1.5 (manufactured by Schneider Kreuznach for Leitz) was well behind the Sonnar 5cm 1:1.5. Only with the introduction of the Summarit 5cm 1:2 the situation began to improve - Leitz now had at least an f2 lens that was comparable to the corresponding Zeiss designs (Biotar 5.8cm 1:2 and the Sonnar 5cm 1:2). The Xenon, the Biotar and well as the Summitar are double gauss lenses, derived from Paul Pudolphs Planar (1896/97). Some additional information on the Planar  / Biotar history can be found here; this article was published in the Sony Fotospiegel 143.

A few remarks on the NEX-5N and the actual testing: As usual I was using a stable Manfrotto 055C tripod and a Manfrotto 410 three way head. The NEX was coupled to the Zeiss / Leitz lenses with a Leica M to NEX adapter from Voigtländer and - if necessary - with an Leica Thread Mount to Leica M Adapter from Leitz. Lenses with M42 thread were coupled using the Sony AF to NEX adapter from Sony, and an M42 to Sony AF adapter. Focusing was always done wide open and in the center of the image, using the attached OLED viewfinder for the NEX-5N (magnification 9x). Focusing usually was quite straight-forward in case of the Zeiss lenses - they have very little longitudinal CAs. The two vintage Leitz lenses shown here had some longitudinal CAs: If the focus was set on the green image, the red image was (slightly) out of focus, and vice versa. I decided to focus "on the spot", which means to get most detail - regardless of remaining color fringing.

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The test image with diagonal horizon. Details both in the corners as well as in the center have the same "infinite" distance

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The classic Elmar 5cm 1:3.5 - here an uncoated sample built in 1936 - has a low contrast, and even in the center and stopped down the details are missing. The corners are quite bad, even though we use only an APS-C sensor. Strong CA's and remaining astigmatism are the main problems.

The Tessar 5cm 1:2.8, computed by Merté in 1931 (here a coated sample from 1957). Nearly one stop faster than the Elmar the lens is nevertheless considerably sharper. The lens, however, must be stopped down to f11 for really sharp APS-C corners. CAs are remarkably well corrected - a notable feature of most classic Carl Zeiss lenses including the Biotar 7.5 cm 1:1.5.

The Sonnar 5cm 1:1.5 (computed 1931/32) from Ludwig Bertele is a masterpiece. About five times faster than the Elmar, it nevertheless was better than the Elmar in nearly every aspect. Remarkably, even stopped down to f11 the Elmar isn't really better than the Sonnar at f1.5! The Sonnar has quite a pronounced fous shift; thus using the direct image from the sensor for focusing is certainly helpful if one wants to get the best out of the Sonnar.The lens shown here is an original LTM Sonnar from 1941 - and not a later "Jupiter-to-Zeiss" conversion. I found the lens, attached to a Leica III from 1941, here in Zurich in a well established photo shop. The Leica owner had died years ago, and his widow was selling the equipment that had been untouched for years - icluding the war time Sonnar LTM.

The lens has pronounced focus-shift when stopped down. Scroll over the image to see the effects of reforcusing at f5.6 (doesn't work on all browsers!)

The Biotar 5.8cm 1:2 was introduced in 1938 as a fast standard lens for the Kine-Exakta. The Kine Exakta was the first SLR for 24x36mm film rolls. Because of the large space occupied by the mirror, the Sonnar lenses were not suitable for the Kine-Exakta. Thus Zeiss had to adopt the Biotar construction scheme (before used as a superfast f1.4 cine lens) for the larger 24x36mm film format. The Biotar is basically a Planar, adapted for scales of about 1:20; while the original Planar was symmetric and therefore best around 1:1.Here a T-coated Biotar in M42 mount for the Contax D, built in 1952, is shown.

The Leitz Summitar from 1939 was Leitz' first well corrected fast lens. However, at f2 the center doesn't become really sharp - mainly due to strong longitudinal CAs. For this test I have chosen to focus the lens for "maximal detail"; this results in pronounced green halos. If one focuses differently, the CAs disappear, but the overall detail is lost (scroll with the mouse over the image to see; doesn't work on all browsers!).

One of the best Zeiss lenses, built by Cosina to high standards: The Zeiss Planar ZM 2/50mm. Actually its focal length is slightly less than 50mm. The detail resolution even at f2 is very good; stopping down increases simply the micro contrast. There are no visible CAs, and there is no focus shift when stopping down - an important detail for those using the lens on rangfinder cameras such as the Leica M series or the Voigtländer Bessa.

The Zeiss C ("classic") Sonnar ZM 1.5/50mm. Its design is a slightly modified Bertele-Sonnar. The intermediate low dispersion (LD) lens in the front triplet of the original Bertele Sonnar was replaced by an "air lens" since high refractive / low dispersion glass now is available. The effect of the modern, improved coating is clearly visible. The overall characteristics of the original Sonnar from 1932 however are preserved: Out-of-focus areas are rendered in an unique way; they are not simply unsharp, but they retain a sharp outline overlaid by a glowing halo.

Below are three images comparing the different characteristics of the Zeiss Planar ZM and the Zeiss Sonnars. While the Planar looks "flat" and somehow boring to my eye, both Sonnars are far more "3D". They are "glowing", and they feel much more "alive". Images taken with the Sonnars at f1.5 have something magic, especially portraits taken in backlight situations. While in the test above the Planar looks much "better" and cleaner, I actually prefer the Sonnar 1.5/50mm for photographic work.

First the old Sonnar 1.5/5cm (1932/41), then the Planar 2/50mm ZM (2005) and finally the C-Sonnar 1.5/50mm ZM (2005); all images below at full aperture.

IMAGES WILLL FOLLOW LATER