Cooke Triplet, Tessar and Planar: E. Ludwig Meritar 50mm f/2.9, Industar-61 L/Z 50mm f/2.8 and Nikon Micro Nikkor 55mm f/3.5 non-Ai (PK-3).

Introduction:

During this test three relatively “slow” ~50mm prime lenses will be compared: E. Ludwig Meritar 50mm f/2.9 from Germany, Industar-61 L/Z 50mm f/2.8 from USSR and Nikon Micro Nikkor 55mm f/3.5 non-Ai (PK-3) from Japan. These lenses have very simple but interesting classical optical formulas: Cooke Triplet (three lens elements in three groups), Tessar (four lens elements in three groups), and the five-lens Planar (exact name - Xenotar - five lens elements in four groups). You can learn more here: Fast Normal Photographic Lens Historic Line Up by Yuri Stangrit

This review will include not only a trivial comparison of the sharpness, but also the analysis (of course within homemade possibility) of the optical aberration of the lenses.

All these lenses were made almost within a decade around 1965-1977. However, the difference in their appearance, workmanship, ease of usage and image quality would judge on a qualitative leap in photo lens designing and manufacturing, that occurred in the 70 years of the last century. So:

Lenses that will be discussed:

E. Ludwig Meritar 50mm f/2.9 normal, prime, manual focus, kit lens for 35mm SLR Exakta (Germany) cameras. The lens-to-camera mount is M42 screw.  It is using the Cooke Triplet optical formula (three lens elements in three groups). To obtain the maximum relative aperture of f2.9 this lens supposes to be made of special sort of the glass (most likely lanthanum). The lens is made in the late 60-ies of XX century. The aperture system has five rounded blades. There is Anti-reflective coating.

Industar-61 L/Z 50mm f/2.8 normal, prime, manual focus lens for 35mm SLR Zenit (USSR) cameras. The lens-to-camera mount is M42 screw.  It is using the Tessar optical formula (four lenses in three groups). The lens was designed with the usage of lanthanum glass in the 60-ies of the XX century, which allowed maximum relative aperture of f2.8. This particular lens is made in 1978. It has six blades of the aperture. In the range of f5.6-f11 aperture forms a hole of six-pointed star shape. It is likely to have single-layer anti-reflective coating.

Nikon Micro Nikkor 55mm f/3.5 non-Ai (PK-3) normal, prime, manual focus macro-lens for 35mm SLR Nikon (Japan) cameras with Nikon F bayonet.  It’s using Planar five lenses optical formula, also known as Xenotar (five elements in four groups). Nikon began producing lenses with such a formula during early 60-ies of XX century. The lens is made in about 1975-77. The aperture system has six non-rounded blades.  There is multilayer anti-reflective coating.

Group photo and Optical formulas:

Parameters for compaison:

Design and usability.
Sharpness of images in the center and at the edge of the frame for a short distance (~ 1.0m)
Sharpness of images in the center and at the edge of the frame for a long distance (~ 150m) Aberrations:
 - Spherical aberration
 - Coma / Astigmatism
 - Longitudinal Chromatic aberration
 - Lateral Chromatic Aberration
A pointed source of light in the background and circles of confusion (bokeh)
Vignetting(the light fall off in the corners of the frame)

Technical Notes:

Camera Sony NEX-6 was used for the comparison. So all conclusions are related to APS-C sensor with a size of 23.6mm x 15.7mm. In case of usage of smaller (Micro4/3) or larger (Full Frame) sensor sizes corner effects (such as coma, for example) would be noticeably different.
Because the concept of "comparison" is only applicable to the measurable parameters, this review was based on as much as possible “technical measurable capability”. Art capabilities of lenses were not taken into consideration.

Design and usability.

E. Ludwig Meritar 50mm f/2.9 provides mixed feeling: on the one hand - it has well built quality, all-metal aluminum case. On the other hand - a sensation of somefrailness.

Usability is poor. The aperture ring can be easily confused with focus ring. Both rings are thin, not comfortable.

Industar-61 L/Z 50mm f/2.8 is made very solidly, with no exceptions.
From the usability point of view this is one of the most pleasant lenses. Focusing ring is very wide and well built. An aperture ring is small enough and prevents accidental change of the setting.

Nikon Micro Nikkor 55mm f/3.5 non-Ai (PK-3), the lens has traditional Japanese manufacturer quality.
In terms of usability it has one drawback - the aperture ring is located too close to the camera (adapter), and often it is very difficult to locate it. In addition, it can be easily confused with a "fake" ring, which placed just a few millimeters up front of the aperture ring.

In addition it should be noted: for all three lenses front lens element is recessed dip into the rim (Nikon - more, Meritar - less), allowing their usage without hood. In this regard, no additional testing for flare prone was conducted.

Sharpness of images in the center and at the edge of the frame for a short distance (~ 1.0m)

Conditions: artificial lighting, ISO400, automatic white balance, Sony NEX-6, a tripod, a two second delay before the shutter release.
A standard test format ... was used. Distance from the model was chosen so that the model covers the entire plane of the frame.For the analysis, two models were used: in the center and at the edge of the frame. Click on the picture to see full size.